@phdthesis{liza2025a,
	address = {Tucson, AZ},
	title = {Aero-{Optical} {Effects} in {High}-{Enthalpy} {Flows}},
	url = {http://hdl.handle.net/10150/679132},
	abstract = {Hypersonic flows present unique challenges to measurements made by sensors emitting electromagnetic waves due to the complex interplay between fluid dynamics, thermodynamics, electrodynamics, atmospheric effects, and chemical reactions in the surrounding environment. In particular, the thermal nonequilibrium and turbulent nature of the flow field can cause both deflection and degradation of optical signals as they traverse the boundary layer, shock layer, and surrounding atmosphere.A comprehensive physical understanding of these phenomena is necessary to accurately assess and predict sensor performance in hypersonic environments. While prior research in Aero-Optical (AO) has predominantly focused on low-speed or low-enthalpy applications where perfect gas assumptions hold, this work investigates the influence of real gas effects and thermal nonequilibrium in high-enthalpy hypersonic flows. High-fidelity Computational Fluid Dynamics (CFD) simulations are employed to quantify the impact of these flow phenomena on optical signal propagation.Two representative cases are examined to explore different fidelity trade-offs: (i) a low-enthalpy, high-flow-resolution case, and (ii) a high-enthalpy, lower-flow-resolution case, where the modeling of chemical and thermal nonequilibrium is critical. To facilitate the analysis of AO distortions from CFD results, an open-source Python package, Hypersonics Aerodynamics Optics Tool (HAOT), was developed as part of this work. All results presented in this dissertation were obtained using HAOT version v1.1.3.This work advances the understanding of AO in high-enthalpy flows by investigating the behavior of AO properties in chemically and thermally nonequilibrium gases. It also examines the influence of internal energy level populations on AO using a State-to-State (StS) approach. In addition, this work includes the development of a computational package for analyzing AO in both high and low-enthalpy regimes under laminar and turbulent flow conditions. The dissertation can be found in https://github.com/mliza/dissertation, and the HAOT package can be found in https://haot.readthedocs.io/en/latest/.},
	language = {English},
	school = {The University of Arizona},
	author = {Liza, Martin E.},
	collaborator = {Hanquist, Kyle M.},
	year = {2025},
	keywords = {group},
}

Hypersonic flows present unique challenges to measurements made by sensors emitting electromagnetic waves due to the complex interplay between fluid dynamics, thermodynamics, electrodynamics, atmospheric effects, and chemical reactions in the surrounding environment. In particular, the thermal nonequilibrium and turbulent nature of the flow field can cause both deflection and degradation of optical signals as they traverse the boundary layer, shock layer, and surrounding atmosphere.A comprehensive physical understanding of these phenomena is necessary to accurately assess and predict sensor performance in hypersonic environments. While prior research in Aero-Optical (AO) has predominantly focused on low-speed or low-enthalpy applications where perfect gas assumptions hold, this work investigates the influence of real gas effects and thermal nonequilibrium in high-enthalpy hypersonic flows. High-fidelity Computational Fluid Dynamics (CFD) simulations are employed to quantify the impact of these flow phenomena on optical signal propagation.Two representative cases are examined to explore different fidelity trade-offs: (i) a low-enthalpy, high-flow-resolution case, and (ii) a high-enthalpy, lower-flow-resolution case, where the modeling of chemical and thermal nonequilibrium is critical. To facilitate the analysis of AO distortions from CFD results, an open-source Python package, Hypersonics Aerodynamics Optics Tool (HAOT), was developed as part of this work. All results presented in this dissertation were obtained using HAOT version v1.1.3.This work advances the understanding of AO in high-enthalpy flows by investigating the behavior of AO properties in chemically and thermally nonequilibrium gases. It also examines the influence of internal energy level populations on AO using a State-to-State (StS) approach. In addition, this work includes the development of a computational package for analyzing AO in both high and low-enthalpy regimes under laminar and turbulent flow conditions. The dissertation can be found in https://github.com/mliza/dissertation, and the HAOT package can be found in https://haot.readthedocs.io/en/latest/.

@phdthesis{liza2025,
	address = {Tucson, AZ},
	type = {Ph.{D}.},
	title = {Aero-{Optical} {Effects} in {High}-{Enthalpy} {Flows}},
	url = {http://hdl.handle.net/10150/679132},
	abstract = {Hypersonic flows present unique challenges to measurements made by sensors emitting electromagnetic waves due to the complex interplay between fluid dynamics, thermodynamics, electrodynamics, atmospheric effects, and chemical reactions in the surrounding environment. In particular, the thermal nonequilibrium and turbulent nature of the flow field can cause both deflection and degradation of optical signals as they traverse the boundary layer, shock layer, and surrounding atmosphere.A comprehensive physical understanding of these phenomena is necessary to accurately assess and predict sensor performance in hypersonic environments. While prior research in Aero-Optical (AO) has predominantly focused on low-speed or low-enthalpy applications where perfect gas assumptions hold, this work investigates the influence of real gas effects and thermal nonequilibrium in high-enthalpy hypersonic flows. High-fidelity Computational Fluid Dynamics (CFD) simulations are employed to quantify the impact of these flow phenomena on optical signal propagation.Two representative cases are examined to explore different fidelity trade-offs: (i) a low-enthalpy, high-flow-resolution case, and (ii) a high-enthalpy, lower-flow-resolution case, where the modeling of chemical and thermal nonequilibrium is critical. To facilitate the analysis of AO distortions from CFD results, an open-source Python package, Hypersonics Aerodynamics Optics Tool (HAOT), was developed as part of this work. All results presented in this dissertation were obtained using HAOT version v1.1.3.This work advances the understanding of AO in high-enthalpy flows by investigating the behavior of AO properties in chemically and thermally nonequilibrium gases. It also examines the influence of internal energy level populations on AO using a State-to-State (StS) approach. In addition, this work includes the development of a computational package for analyzing AO in both high and low-enthalpy regimes under laminar and turbulent flow conditions. The dissertation can be found in https://github.com/mliza/dissertation, and the HAOT package can be found in https://haot.readthedocs.io/en/latest/.},
	language = {English},
	school = {The University of Arizona},
	author = {Liza, Martin E.},
	collaborator = {Hanquist, Kyle M.},
	year = {2025},
	keywords = {group},
}

Hypersonic flows present unique challenges to measurements made by sensors emitting electromagnetic waves due to the complex interplay between fluid dynamics, thermodynamics, electrodynamics, atmospheric effects, and chemical reactions in the surrounding environment. In particular, the thermal nonequilibrium and turbulent nature of the flow field can cause both deflection and degradation of optical signals as they traverse the boundary layer, shock layer, and surrounding atmosphere.A comprehensive physical understanding of these phenomena is necessary to accurately assess and predict sensor performance in hypersonic environments. While prior research in Aero-Optical (AO) has predominantly focused on low-speed or low-enthalpy applications where perfect gas assumptions hold, this work investigates the influence of real gas effects and thermal nonequilibrium in high-enthalpy hypersonic flows. High-fidelity Computational Fluid Dynamics (CFD) simulations are employed to quantify the impact of these flow phenomena on optical signal propagation.Two representative cases are examined to explore different fidelity trade-offs: (i) a low-enthalpy, high-flow-resolution case, and (ii) a high-enthalpy, lower-flow-resolution case, where the modeling of chemical and thermal nonequilibrium is critical. To facilitate the analysis of AO distortions from CFD results, an open-source Python package, Hypersonics Aerodynamics Optics Tool (HAOT), was developed as part of this work. All results presented in this dissertation were obtained using HAOT version v1.1.3.This work advances the understanding of AO in high-enthalpy flows by investigating the behavior of AO properties in chemically and thermally nonequilibrium gases. It also examines the influence of internal energy level populations on AO using a State-to-State (StS) approach. In addition, this work includes the development of a computational package for analyzing AO in both high and low-enthalpy regimes under laminar and turbulent flow conditions. The dissertation can be found in https://github.com/mliza/dissertation, and the HAOT package can be found in https://haot.readthedocs.io/en/latest/.

@inproceedings{white2025,
	title = {Formulation of an {Uncertainty} {Analysis} {Methodology} for {Computational} {Fluid} {Dynamics} of {External} {Flows} {Over} {Launch} {Vehicles}},
	doi = {10.2514/6.2025-3409},
	abstract = {Space launch vehicles are often engineered with large safety factors due to the scarcity and cost of ground tests. In addition, these vehicles often carry expensive and delicate payloads that must go through extreme launch conditions. Computational Fluid Dynamics (CFD) can be utilized to support the design of these vehicles but often have uncertainty and errors associated with them that are often not fully quantified. This paper provides a methodology and investigation for quantifying and estimating the uncertainty for CFD over space launch vehicles when no experimental data exists. A generic launch vehicle was used for this study. The primary output quantities of interest for the study are the aerodynamic coefficients. While there are numerous sources of uncertainty, this study investigates the impact of mesh quality, boundary conditions, and turbulence models. The largest uncertainty lies in the y-moment coefficient, where the y-axis is aligned with the angle of attack, and is due to perturbing the turbulence model for a zero-degree angle of attack configuration or perturbing the mesh quality for a six-degree angle of attack configuration. The smallest uncertainty is in the x-moment coefficient, with a zero percent uncertainty for all configurations.},
	urldate = {2025-09-09},
	booktitle = {{AIAA} {AVIATION} {FORUM} {AND} {ASCEND} 2025},
	publisher = {AIAA Paper 2025-3409},
	author = {White, Avery and Hanquist, Kyle M.},
	year = {2025},
}

Space launch vehicles are often engineered with large safety factors due to the scarcity and cost of ground tests. In addition, these vehicles often carry expensive and delicate payloads that must go through extreme launch conditions. Computational Fluid Dynamics (CFD) can be utilized to support the design of these vehicles but often have uncertainty and errors associated with them that are often not fully quantified. This paper provides a methodology and investigation for quantifying and estimating the uncertainty for CFD over space launch vehicles when no experimental data exists. A generic launch vehicle was used for this study. The primary output quantities of interest for the study are the aerodynamic coefficients. While there are numerous sources of uncertainty, this study investigates the impact of mesh quality, boundary conditions, and turbulence models. The largest uncertainty lies in the y-moment coefficient, where the y-axis is aligned with the angle of attack, and is due to perturbing the turbulence model for a zero-degree angle of attack configuration or perturbing the mesh quality for a six-degree angle of attack configuration. The smallest uncertainty is in the x-moment coefficient, with a zero percent uncertainty for all configurations.

@inproceedings{larsen2025,
	title = {Vibrational {State}-to-{State} and {Shock}-{Tube} {Thermochemical} {Modeling} of {Hypersonic} {Flows}},
	doi = {10.2514/6.2025-3560},
	abstract = {Hypersonic flows give rise to nonequilibrium conditions that require increased precision and more specialized simulations to model the collisions between excited gas molecules. While the rotational energy mode is often in equilibrium with the translation mode, the vibrational mode requires more collisions, and thus more time, to reach equilibrium. In this paper, we investigate four main areas of interest. First, state-resolved rates are often generated on different potential energy surface so we investigate ways to do a consistent mapping from one energy surface to another. Next, vibrational state-to-state modeling is investigated, through analysis of existing data and the implementation into existing hypersonic code. Due to differences in energy levels between existing data, data mapping methods are investigated to ensure uniformity in simulations. Further, nonequilibrium effects for canonical flows are modeled using both one-temperature and two-temperature models. Finally, the modeling of one-dimensional shock flows is investigated to prepare for the introduction of state-to-state models within these shock flows.},
	urldate = {2025-09-09},
	booktitle = {{AIAA} {AVIATION} {FORUM} {AND} {ASCEND} 2025},
	publisher = {AIAA Paper 2025-3560},
	author = {Larsen, Aaron and Hanquist, Kyle M.},
	year = {2025},
}

Hypersonic flows give rise to nonequilibrium conditions that require increased precision and more specialized simulations to model the collisions between excited gas molecules. While the rotational energy mode is often in equilibrium with the translation mode, the vibrational mode requires more collisions, and thus more time, to reach equilibrium. In this paper, we investigate four main areas of interest. First, state-resolved rates are often generated on different potential energy surface so we investigate ways to do a consistent mapping from one energy surface to another. Next, vibrational state-to-state modeling is investigated, through analysis of existing data and the implementation into existing hypersonic code. Due to differences in energy levels between existing data, data mapping methods are investigated to ensure uniformity in simulations. Further, nonequilibrium effects for canonical flows are modeled using both one-temperature and two-temperature models. Finally, the modeling of one-dimensional shock flows is investigated to prepare for the introduction of state-to-state models within these shock flows.

@inproceedings{bemis2025,
	title = {Stationary {Crossflow} and {Traveling} {Instabilities} for a {Slab} {Delta} in {Hypersonic} {Flow}},
	doi = {10.2514/6.2025-3536},
	abstract = {Stationary crossflow and traveling instabilities on a ‘slab delta’ model were investigated in a hypersonic flow. Experiments were conducted in the AFOSR–Notre Dame Large Mach-6 Quiet Tunnel at nominally zero angle of attack and yaw at unit Reynolds numbers from 4.1 · 10{\textasciicircum}6 /m to 12.2 · 10{\textasciicircum}6 /m. Infrared thermography was employed to measure the surface heat-flux distribution, assess the boundary-layer state, track the paths of the stationary crossflow waves, and quantify the flow uniformity. These measurements visualized characteristic streamwise heating streaks and outboard transition lobes. Linear Stability Theory (LST) calculations using the Linear Parabolized Stability Equation (LPSE) at Re∞ = 11.78 ·10{\textasciicircum}6 /m predicted the most-amplified waves would have a wavelength of 6 mm, a frequency of 13.75 kHz, and propagate towards the centerline with a wave speed of 81 m/s. Traveling waves were measured using surface-flush Kulite pressure transducer trios. Cross-spectral analysis of the pressure signals yielded wave angles and phase speeds as functions of frequency. Traveling waves were observed at Reynolds numbers ranging from 4.1 · 10{\textasciicircum}6 /m to 9.8 · 10{\textasciicircum}6 /m, with peak frequencies centered in the range from 7 to 10 kHz. Within experimental uncertainties, the wave angle and phase were found to be largely invariant with Reynolds number. The variation with frequency of experimentally obtained wave angle and phase speed agreed with LST predictions, but experiments exhibited mild left/right differences and phase-speed discrepancies not predicted by LST.},
	urldate = {2025-09-09},
	booktitle = {{AIAA} {AVIATION} {FORUM} {AND} {ASCEND} 2025},
	publisher = {AIAA Paper 2025-3536},
	author = {Bemis, Benjamin L. and Peck, Madeline M. and Hanquist, Kyle M. and Gordeyev, Stanislav and Juliano, Thomas},
	year = {2025},
}

Stationary crossflow and traveling instabilities on a ‘slab delta’ model were investigated in a hypersonic flow. Experiments were conducted in the AFOSR–Notre Dame Large Mach-6 Quiet Tunnel at nominally zero angle of attack and yaw at unit Reynolds numbers from 4.1 · 10\textasciicircum6 /m to 12.2 · 10\textasciicircum6 /m. Infrared thermography was employed to measure the surface heat-flux distribution, assess the boundary-layer state, track the paths of the stationary crossflow waves, and quantify the flow uniformity. These measurements visualized characteristic streamwise heating streaks and outboard transition lobes. Linear Stability Theory (LST) calculations using the Linear Parabolized Stability Equation (LPSE) at Re∞ = 11.78 ·10\textasciicircum6 /m predicted the most-amplified waves would have a wavelength of 6 mm, a frequency of 13.75 kHz, and propagate towards the centerline with a wave speed of 81 m/s. Traveling waves were measured using surface-flush Kulite pressure transducer trios. Cross-spectral analysis of the pressure signals yielded wave angles and phase speeds as functions of frequency. Traveling waves were observed at Reynolds numbers ranging from 4.1 · 10\textasciicircum6 /m to 9.8 · 10\textasciicircum6 /m, with peak frequencies centered in the range from 7 to 10 kHz. Within experimental uncertainties, the wave angle and phase were found to be largely invariant with Reynolds number. The variation with frequency of experimentally obtained wave angle and phase speed agreed with LST predictions, but experiments exhibited mild left/right differences and phase-speed discrepancies not predicted by LST.

@inproceedings{grover_comparative_2025,
	title = {Comparative {Analysis} of {Thermophysics} {Models} for the {Simulations} of {Nonequilibrium} {Flow}},
	abstract = {Advances in computational capabilities have allowed for the calculation of canonical hypersonic flows using the direct molecular simulation method. DMS is a particle method that uses quantum mechanically derived interaction potentials to simulate molecular collisions within a flow field. Since these interaction potentials are the only modeling inputs used in the simulation, all flow features can solely be attributed to the ab initio potential energy surfaces. The fundamental nature of these simulations lends to be used as benchmarks to assess lower fidelity models. In this work we investigated two canonical hypersonic flows, where the dominant gas-phase chemical activity was the dissociation of free stream diatomic species: (a) Mach 21 nitrogen flow over a blunt wedge and (b) Mach 8.2 oxygen flow over a double cone geometry. For the comparative analysis we consider seven actively used CFD codes and five thermochemical models. It is observed that new generation of thermochemistry models based in ab initio provide solutions that are more physical and compare favorably to the first principles DMS.},
	urldate = {2025-07-09},
	booktitle = {{AIAA} {SCITECH} 2025 {Forum}},
	publisher = {AIAA 2025-0641},
	author = {Grover, Maninder S. and Valentini, Paolo and Bisek, Nicholas J. and Jo, Sung Min and Davuluri, Raghava and Martin, Alexandre and Notey, Aakanksha and Panesi, Marco and Andrienko, Daniil and Hanquist, Kyle M. and Fraijo, Daniel},
	year = {2025},
}

Advances in computational capabilities have allowed for the calculation of canonical hypersonic flows using the direct molecular simulation method. DMS is a particle method that uses quantum mechanically derived interaction potentials to simulate molecular collisions within a flow field. Since these interaction potentials are the only modeling inputs used in the simulation, all flow features can solely be attributed to the ab initio potential energy surfaces. The fundamental nature of these simulations lends to be used as benchmarks to assess lower fidelity models. In this work we investigated two canonical hypersonic flows, where the dominant gas-phase chemical activity was the dissociation of free stream diatomic species: (a) Mach 21 nitrogen flow over a blunt wedge and (b) Mach 8.2 oxygen flow over a double cone geometry. For the comparative analysis we consider seven actively used CFD codes and five thermochemical models. It is observed that new generation of thermochemistry models based in ab initio provide solutions that are more physical and compare favorably to the first principles DMS.

@article{xu_heat_2025,
	title = {Heat flux distribution and deviation of stagnation point on blunt body under atmospheric dense environment},
	volume = {319},
	issn = {03605442},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0360544225006498},
	doi = {10.1016/j.energy.2025.135007},
	abstract = {Rocket sled is a large ground dynamic test system that obtains model test data on a special ground track. To accurately predict heat flux on rocket sled’s surface, a similar blunt body model is utilized in this study. The effects of flow temperature, Mach number, wall temperature, angle of attack and other parameters on aerodynamic heating at standard atmosphere are analyzed based on computational fluid dynamics (CFD) simulation. The results show that heat flux at stagnation point is 4 MW/m2 at Mach 5. However, maximum heat flux on surface of blunt body head is 13 MW/m2, which deviates 5 mm from stagnation point in horizontal direction. These deviation points are distributed around axis of the cone, forming a band called pseudo-stagnation ring. In two dimensions, bluntness and flight height of cone directly affect position of “pseudo-stagnation point”. This position gradually approaches stagnation point as flight altitude increases. At 30 km altitude, “pseudo-stagnation point” position will not be offset. And at an altitude of 20–30 km, “pseudo-stagnation point” quickly falls back to the stagnation point. Additionally, pseudo-stagnation point’s displacement is inversely related to cone’s bluntness, and an increase in angle of attack augments separation from stagnation point on both windward and leeward surfaces.},
	language = {en},
	urldate = {2025-05-29},
	journal = {Energy},
	author = {Xu, Bin and Huang, Tianchen and Jing, Jianbin and Zhang, Chuanxia and Li, Kang and Wang, Yangliang and Ye, Taohong},
	month = mar,
	year = {2025},
	pages = {135007},
}

Rocket sled is a large ground dynamic test system that obtains model test data on a special ground track. To accurately predict heat flux on rocket sled’s surface, a similar blunt body model is utilized in this study. The effects of flow temperature, Mach number, wall temperature, angle of attack and other parameters on aerodynamic heating at standard atmosphere are analyzed based on computational fluid dynamics (CFD) simulation. The results show that heat flux at stagnation point is 4 MW/m2 at Mach 5. However, maximum heat flux on surface of blunt body head is 13 MW/m2, which deviates 5 mm from stagnation point in horizontal direction. These deviation points are distributed around axis of the cone, forming a band called pseudo-stagnation ring. In two dimensions, bluntness and flight height of cone directly affect position of “pseudo-stagnation point”. This position gradually approaches stagnation point as flight altitude increases. At 30 km altitude, “pseudo-stagnation point” position will not be offset. And at an altitude of 20–30 km, “pseudo-stagnation point” quickly falls back to the stagnation point. Additionally, pseudo-stagnation point’s displacement is inversely related to cone’s bluntness, and an increase in angle of attack augments separation from stagnation point on both windward and leeward surfaces.

@inproceedings{grover2025,
	title = {Comparative {Analysis} of {Thermophysics} {Models} for the {Simulations} of {Nonequilibrium} {Flow}},
	booktitle = {{AIAA} {SciTech} 2025 {Forum}},
	publisher = {AIAA Paper 2025-0641},
	author = {Grover, Maninder S and Valentini, Paulo and Bisek, Nicholas J. and Jo, Sung Min and Davuluri, Raghava and Martin, Alexandre and Notey, Aakanksha and Panesi, Marco and Andrienko, Daniil and Hanquist, Kyle M.},
	year = {2025},
}

@inproceedings{oveissi2025,
	title = {Adaptive {Combustion} {Regulation} in {High}-{Fidelity} {Computational} {Model} of {Solid} {Fuel} {Ramjet}},
	booktitle = {{AIAA} {SciTech} 2025 {Forum}},
	publisher = {AIAA Paper 2025-0352},
	author = {Oveissi, Parham and Khokhar, Gohar and Hanquist, Kyle M. and Goel, Ankit},
	year = {2025},
	keywords = {own},
}

@inproceedings{oveissi2025a,
	title = {Learning-based {Thrust} {Regulation} of {Solid}-{Fuel} {Ramjet} in {Flight} {Conditions}},
	booktitle = {{AIAA} {SciTech} 2025 {Forum}},
	publisher = {AIAA Paper 2025-2805},
	author = {Oveissi, Parham and Goel, Ankit and Mcbeth, Joshua and Hanquist, Kyle M.},
	year = {2025},
	keywords = {own},
}

@inproceedings{nelson-melby2025,
	title = {Numerical {Study} for {Design} of {Experiment} on {Aero}-{Optical} {Effects} of {Crossflow} {Waves} in {Hypersonic} {Flow}},
	booktitle = {{AIAA} {SciTech} 2025 {Forum}},
	publisher = {AIAA Paper 2025-2769},
	author = {Nelson-Melby, Leif and Khokhar, Gohar and Hanquist, Kyle M. and Peck, Madeline and Bemis, Benjamin and Juliano, Thomas J and Gordeyev, Stanislav},
	year = {2025},
	keywords = {own},
}

@inproceedings{mcbeth2025,
	title = {Investigation of {Solid} {Fuel} {Ramjets} using {Analytical} {Theory} and {Computational} {Fluid} {Dynamics}},
	booktitle = {{AIAA} {SciTech} 2025 {Forum}},
	publisher = {AIAA Paper 2025-0392},
	author = {Khokhar, Gohar and McBeth, Joshua and Hanquist, Kyle M. and Oveissi, Parham and Goel, Ankit},
	year = {2025},
	keywords = {own},
}

@phdthesis{paxton2024,
	address = {Brisbane, Austrailia},
	title = {Investigation into electron transpiration cooling in hypersonic flows},
	school = {The University of Queensland},
	author = {Paxton, O.},
	year = {2024},
}

@inproceedings{kinsey_measurement_2024,
	address = {Las Vegas, Nevada},
	title = {Measurement of {Heat} {Flux} on a {3D} {Printed} {Hemisphere} {With} {IR} {Thermography}},
	isbn = {978-1-62410-716-0},
	url = {https://arc.aiaa.org/doi/10.2514/6.2024-4284},
	doi = {10.2514/6.2024-4284},
	language = {en},
	urldate = {2025-05-22},
	booktitle = {{AIAA} {AVIATION} {FORUM} {AND} {ASCEND} 2024},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Kinsey, Brian and Skora, Adam and Mokler, Matthew and Wheeler, Makena and Dahl, Kirk and Craig, Stuart A. and Portoni, Phillip and Basore, Kevin and Strauss, Tristan and Dean, Tyler and Arndt, Alexander and Wernz, Stefan},
	month = jul,
	year = {2024},
}

@misc{larsen2024a,
	title = {Theory and {Simulation} of {High}-{Temperature} {Gas} in {Shock} {Tubes}},
	author = {Larsen, Aaron and Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2024},
	keywords = {own, presentation},
}

@misc{larsen2024,
	title = {Vibrational {State}-to-{State} {Thermochemical} {Modeling} of {High}-{Temperature} {Oxgyen} {Flows}},
	author = {Larsen, Aaron and Hanquist, Kyle M.},
	year = {2024},
	keywords = {own, presentation},
}

@misc{hanquist2024,
	title = {Ongoing work using {SU2} for hypersonic applications},
	url = {https://su2foundation.org/su2conference2024/},
	author = {Hanquist, Kyle M. and Khokhar, Gohar and Larsen, Aaron and Liza, Martin E. and White, Avery and Nelson-Melby, Leif and Schmidt, Sydney and Fraijo, Daniel and Horth, Shelby and Tuba, Ana},
	year = {2024},
	keywords = {own, presentation},
}

@article{liza2024,
	title = {Numerical {Investigation} of {Nonequilibrium} {Effects} on {Aero}-{Optics} in {Hypersonic} {Flows}},
	journal = {Journal of Thermophysics and Heat Transfer (under review)},
	author = {Liza, Martin E. and Hanquist, Kyle M.},
	year = {2024},
	keywords = {own},
}

@inproceedings{oveissi2024,
	title = {Adaptive {Combustion} {Regulation} in {Solid} {Fuel} {Ramjet}},
	doi = {10.2514/6.2024-0743},
	abstract = {Control of the combustion process under hypersonic conditions remains a challenging problem. In this paper, we investigate the application of a data-driven, learning-based control technique to regulate a combustion process evolving inside a solid fuel ramjet to regulate the generated thrust under unknown operating conditions. A computational model to simulate the combustion dynamics is developed by combining compressible flow theory with equilibrium chemistry. The computational model is simulated to ascertain the combustion dynamics' stability and establish the engine's operational envelope. Based on retrospective cost optimization, an online learning controller is then integrated with the computational model to regulate the generated thrust. Numerical simulation results are presented to demonstrate the robustness of the adaptive control system.},
	booktitle = {{AIAA} {SCITECH} 2024 {Forum}},
	publisher = {AIAA Paper 2024-0743},
	author = {Oveissi, Parham and Goel, Ankit and Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2024},
	keywords = {own},
}

Control of the combustion process under hypersonic conditions remains a challenging problem. In this paper, we investigate the application of a data-driven, learning-based control technique to regulate a combustion process evolving inside a solid fuel ramjet to regulate the generated thrust under unknown operating conditions. A computational model to simulate the combustion dynamics is developed by combining compressible flow theory with equilibrium chemistry. The computational model is simulated to ascertain the combustion dynamics' stability and establish the engine's operational envelope. Based on retrospective cost optimization, an online learning controller is then integrated with the computational model to regulate the generated thrust. Numerical simulation results are presented to demonstrate the robustness of the adaptive control system.

@article{tumuklu2024,
	title = {Hypersonic turbulence wake modeling from rarefied to continuum regimes},
	volume = {2996},
	doi = {10.1063/5.0187575},
	abstract = {Hypersonic flows over a cylinder are studied to investigate the unsteady characteristics of rarefied and continuum turbulent wake flows. To do this end, an open-source DSMC solver, SPARTA, is used to capture large gradients associated with shock expansion waves separation region interactions especially in the wake region. Conversely, continuum simulations are carried out using an open-source continuum non-equilibrium solver, SU2-NEMO, for relatively low-pressure rarefied nature of flows with a freestream pressure of up to 100 Pa. Comparisons were made using SPARTA and SU2-NEMO at moderately low freestream pressures of 100 Pa for NS and very good agreement is achieved using continuum and rarefied solvers, indicating that DSMC and continuum numerical parameters are accurately selected. Numerical probes are inserted at various locations to study the temporal and turbulence characteristics by performing ensemble averaging each time step of DSMC. Consistent with previous numerical studies, x-velocity, y-velocity, and cross-velocity fluctuations are mostly dominant in the wake, bow, and tail shock region. For higher pressure cases, temporal characteristics of residuals are reported to calculate the frequency of oscillations seen in the wake with various Reynolds numbers (Re). The frequency of oscillations is found to be in relatively good agreement with previous experimental measurements and tends to increase with Re.},
	language = {en},
	number = {1},
	journal = {AIP Conference Proceedings},
	author = {Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2024},
	keywords = {own},
}

Hypersonic flows over a cylinder are studied to investigate the unsteady characteristics of rarefied and continuum turbulent wake flows. To do this end, an open-source DSMC solver, SPARTA, is used to capture large gradients associated with shock expansion waves separation region interactions especially in the wake region. Conversely, continuum simulations are carried out using an open-source continuum non-equilibrium solver, SU2-NEMO, for relatively low-pressure rarefied nature of flows with a freestream pressure of up to 100 Pa. Comparisons were made using SPARTA and SU2-NEMO at moderately low freestream pressures of 100 Pa for NS and very good agreement is achieved using continuum and rarefied solvers, indicating that DSMC and continuum numerical parameters are accurately selected. Numerical probes are inserted at various locations to study the temporal and turbulence characteristics by performing ensemble averaging each time step of DSMC. Consistent with previous numerical studies, x-velocity, y-velocity, and cross-velocity fluctuations are mostly dominant in the wake, bow, and tail shock region. For higher pressure cases, temporal characteristics of residuals are reported to calculate the frequency of oscillations seen in the wake with various Reynolds numbers (Re). The frequency of oscillations is found to be in relatively good agreement with previous experimental measurements and tends to increase with Re.

@inproceedings{tumuklu2024a,
	title = {Effect of {Spanwise} {Instabilities} on {Hypersonic} {Flows}},
	doi = {10.2514/6.2024-3834},
	abstract = {This study investigates hypersonic Mach 7.1 flows with varying unit Reynolds numbers of 5.2E+4, 1.04E+5, and 4.14E+5 1/m over a double wedge with wedge angles of 0/30◦, 5/30◦, and 30/45◦ using both 2D and 3D configurations. Significant influences of wedge angles on shock interactions, flow dynamics, and surface parameters are observed. A detailed analysis of the temporal characteristics of the flow and surface fields is carried out. The characteristics of self-induced spanwise instabilities in the relatively large separation region are closely examined. Increasing the wedge angles led to a nonlinear increase in spanwise instabilities.},
	urldate = {2024-09-16},
	booktitle = {{AIAA} {AVIATION} {FORUM} {AND} {ASCEND} 2024},
	publisher = {AIAA Paper 2024-3834},
	author = {Tumuklu, Ozgur},
	year = {2024},
	doi = {10.2514/6.2024-3834},
	note = {\_eprint: https://arc.aiaa.org/doi/pdf/10.2514/6.2024-3834},
}

This study investigates hypersonic Mach 7.1 flows with varying unit Reynolds numbers of 5.2E+4, 1.04E+5, and 4.14E+5 1/m over a double wedge with wedge angles of 0/30◦, 5/30◦, and 30/45◦ using both 2D and 3D configurations. Significant influences of wedge angles on shock interactions, flow dynamics, and surface parameters are observed. A detailed analysis of the temporal characteristics of the flow and surface fields is carried out. The characteristics of self-induced spanwise instabilities in the relatively large separation region are closely examined. Increasing the wedge angles led to a nonlinear increase in spanwise instabilities.

@inproceedings{codron2024,
	title = {Development of a {Small}-{Scale} {Arc} {Jet} {Facility} for {Plasma} {Diagnostic} {Research} and {Material} {Testing}},
	booktitle = {{AIAA} {Aviation}},
	author = {Codron, Douglas A. and Thelen, Ryan and Kennedy, Ryan and Pearson, Justin H.},
	year = {2024},
}

@inproceedings{gangemi2024,
	title = {Multicomponent simulation of plasma-sheath formation in presence of an emitting surface},
	abstract = {In a wall-confined environment, the plasma behaviour can be identified by dividing the domain in two main regions: the bulk, where the quasi-neutrality prevails (the charge density is close to zero) and the sheath region near the walls, where positive space charge is built. This phenomenon is due to a higher mobility of electrons, creating an electric potential structure that accelerates the ions towards the surface and repels the electrons. In this work we present a multicomponent approach to the problem of the formation of sheath in the presence of a thermionic emissive surface: this type of materials are of particular interest in the modelling of emissive probes or in novel thermal protection systems strategies that include the use of electron transpiration cooling materials for hypersonic leading edges.},
	urldate = {2024-04-12},
	booktitle = {{AIAA} {SCITECH} 2024 {Forum}},
	publisher = {AIAA Paper 2024-2605},
	author = {Gangemi, Giuseppe Matteo and Hillewaert, Koen and Magin, Thierry and Laguna, Alejandro Alvarez},
	year = {2024},
}

In a wall-confined environment, the plasma behaviour can be identified by dividing the domain in two main regions: the bulk, where the quasi-neutrality prevails (the charge density is close to zero) and the sheath region near the walls, where positive space charge is built. This phenomenon is due to a higher mobility of electrons, creating an electric potential structure that accelerates the ions towards the surface and repels the electrons. In this work we present a multicomponent approach to the problem of the formation of sheath in the presence of a thermionic emissive surface: this type of materials are of particular interest in the modelling of emissive probes or in novel thermal protection systems strategies that include the use of electron transpiration cooling materials for hypersonic leading edges.

@inproceedings{morton2024,
	title = {{CFD} 2030: {Hypersonic} {Modeling} \& {Simulation} {Grand} {Challenge}},
	shorttitle = {{CFD} 2030},
	abstract = {This paper outlines a grand challenge for simulation of hypersonic vehicles to add to the set of grand challenges the AIAA CFD2030 Integrating Committee has proposed for maneuvering aircraft{\textasciicircum}1, turbo-machinery engines{\textasciicircum}2, and space launch vehicles{\textasciicircum}3. Two classes of hypersonic vehicles are proposed for the hypersonic grand challenge to highlight a large number of the physical modeling challenges experienced in hypersonic vehicle flight. The two vehicle classes are referred to as the Boost Glide Concept (BGC) and the Air-Breathing Cruiser (ABC). A detailed representation of the BGC and ABC required simulation capabilities is presented, as well as a set of sub-challenges for each. Finally, a timeline is presented that completes the hypersonic grand challenge demonstrations by the end of 2030.},
	urldate = {2024-04-12},
	booktitle = {{AIAA} {SCITECH} 2024 {Forum}},
	publisher = {AIAA Paper 2024-0683},
	author = {Morton, Scott A. and Cummings, Russell M.},
	year = {2024},
}

This paper outlines a grand challenge for simulation of hypersonic vehicles to add to the set of grand challenges the AIAA CFD2030 Integrating Committee has proposed for maneuvering aircraft\textasciicircum1, turbo-machinery engines\textasciicircum2, and space launch vehicles\textasciicircum3. Two classes of hypersonic vehicles are proposed for the hypersonic grand challenge to highlight a large number of the physical modeling challenges experienced in hypersonic vehicle flight. The two vehicle classes are referred to as the Boost Glide Concept (BGC) and the Air-Breathing Cruiser (ABC). A detailed representation of the BGC and ABC required simulation capabilities is presented, as well as a set of sub-challenges for each. Finally, a timeline is presented that completes the hypersonic grand challenge demonstrations by the end of 2030.

@article{jin2024,
	title = {Investigation of the influence mechanism of hypersonic flow field environment on thermionic emission efficiency},
	volume = {226},
	issn = {0017-9310},
	doi = {10.1016/j.ijheatmasstransfer.2024.125502},
	abstract = {Electron Transpiration Cooling (ETC) is a novel thermal management method that utilizes thermionic emission to cool the leading edge surface of a hypersonic vehicle. Establishing a thermionic emission model that accounts for the hypersonic flow field environment is imperative for accurately predicting the thermal protection efficiency of ETC. A thermionic emission dual-sheath model was established, considering the impact of hypersonic non-equilibrium flow field particle parameters on thermal electron emission. The virtual cathode threshold was obtained through numerical analysis, considering the influence of particles parameters and surface thermoelectric material parameters in a non-equilibrium flow field. Distribution of sheath potential and particle number density in plasma sheath region were performed at a range of conditions. Thermionic emission efficiency approached 80 \% as the plasma ion density was 5 × 20 m−3 and the work function was 2 eV. The results showed that plasma ions have different degrees of neutralization effect on thermal emission electrons depending on the flow field and surface material characteristics, ultimately causing varying surface thermionic emission efficiency.},
	urldate = {2024-04-05},
	journal = {International Journal of Heat and Mass Transfer},
	author = {Jin, Hua and Mi, Zhitong and Li, Zhuoran and Wu, Xiao and Sui, Zhuochen and Dong, Pan},
	month = jul,
	year = {2024},
	keywords = {Dual-sheath model, Electron transpiration cooling (ETC), Hypersonic vehicle, Thermal management, Thermionic emission},
}

Electron Transpiration Cooling (ETC) is a novel thermal management method that utilizes thermionic emission to cool the leading edge surface of a hypersonic vehicle. Establishing a thermionic emission model that accounts for the hypersonic flow field environment is imperative for accurately predicting the thermal protection efficiency of ETC. A thermionic emission dual-sheath model was established, considering the impact of hypersonic non-equilibrium flow field particle parameters on thermal electron emission. The virtual cathode threshold was obtained through numerical analysis, considering the influence of particles parameters and surface thermoelectric material parameters in a non-equilibrium flow field. Distribution of sheath potential and particle number density in plasma sheath region were performed at a range of conditions. Thermionic emission efficiency approached 80 % as the plasma ion density was 5 × 20 m−3 and the work function was 2 eV. The results showed that plasma ions have different degrees of neutralization effect on thermal emission electrons depending on the flow field and surface material characteristics, ultimately causing varying surface thermionic emission efficiency.

@article{evans2023,
	title = {Performance of a solid-fuel ramjet combustor with bypass air addition},
	volume = {39},
	url = {https://doi.org/10.2514/1.B38788},
	abstract = {The influence of bypass air addition on the performance of a solid-fuel ramjet combustor was investigated. Experiments were performed with cylindrical center-perforated hydroxyl-terminated polybutadiene fuel grains and unvitiated heated air at flight-relevant pre-ignition combustor inlet total temperatures. The core air mass flow rate was kept constant, whereas the bypass ratio was varied from 0 to 30\% with consistent pre-combustion chamber pressures. The average regression rate and mass flow rate of the fuel were greatest for the 0\% bypass ratio case. The regression rate decreased for the 30\% bypass ratio and for cases in which carbon black was not added to the fuel grain. Increasing the mass flow rate of air bypassed to the secondary combustion zone reduced the overall chamber pressure. The thrust increased with the increasing bypass ratio. The effect of bypass air on the chamber pressure yielded lower characteristic velocities at the 30\% bypass ratio than at the 0 and 15\% bypass ratios. The combustion efficiency of the device was maximized for the 15\% bypass ratio. The key outcomes of the bypass air addition are to lower the global equivalence ratio and to reduce the combustion chamber pressure such that there is a nonzero bypass ratio for which the combustion efficiency is maximized},
	number = {2},
	journal = {Journal of Propulsion and Power},
	author = {Evans, Jay V and Senior, William CB and Gejji, Rohan M and Slabaugh, Carson D.},
	year = {2023},
	pages = {167--175},
}

The influence of bypass air addition on the performance of a solid-fuel ramjet combustor was investigated. Experiments were performed with cylindrical center-perforated hydroxyl-terminated polybutadiene fuel grains and unvitiated heated air at flight-relevant pre-ignition combustor inlet total temperatures. The core air mass flow rate was kept constant, whereas the bypass ratio was varied from 0 to 30% with consistent pre-combustion chamber pressures. The average regression rate and mass flow rate of the fuel were greatest for the 0% bypass ratio case. The regression rate decreased for the 30% bypass ratio and for cases in which carbon black was not added to the fuel grain. Increasing the mass flow rate of air bypassed to the secondary combustion zone reduced the overall chamber pressure. The thrust increased with the increasing bypass ratio. The effect of bypass air on the chamber pressure yielded lower characteristic velocities at the 30% bypass ratio than at the 0 and 15% bypass ratios. The combustion efficiency of the device was maximized for the 15% bypass ratio. The key outcomes of the bypass air addition are to lower the global equivalence ratio and to reduce the combustion chamber pressure such that there is a nonzero bypass ratio for which the combustion efficiency is maximized

@misc{vulcan2023,
	title = {Vulcan {Launch} {Systems} {User}'s {Guide}},
	url = {https://www.ulalaunch.com/docs/default-source/default-document-library/2023_vulcan_user_guide.pdf?sfvrsn=37856b50_1},
	month = oct,
	year = {2023},
}

@inproceedings{Gupta2023,
	address = {Reston, Virginia},
	title = {Assessment of optical propagation models with application to hypersonic entry},
	isbn = {978-1-62410-699-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2023-0817},
	doi = {10.2514/6.2023-0817},
	booktitle = {{AIAA} {SCITECH} 2023 forum},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Gupta, Anubhav and Mesalles Ripoll, Pol and Campbell, Nicholas S. and Argrow, Brian},
	month = jan,
	year = {2023},
}

@inproceedings{deboskey2023,
	title = {The {Influence} of {Chemical} {Reaction} {Models} on {Combustion} {Dynamics} in an {Opposed}-{Flow} {Solid} {Fuel} {Burner}},
	doi = {10.2514/6.2023-0161},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-0161.vidWe describe the differences in the combustion behavior within a model opposed-flow solid fuel burner produced by three different chemical reaction models: a two-step global mechanism, a six-step global mechanism, and a pressure-comprehensive skeletal model, all of which assume butadiene as the primary fuel source. Details of the implementation of these models in conjunction with an equilibrium interfacial pyrolysis model for the solid gas phase change process are provided. Of particular interest are the differences in flame structure and dynamics predicted by each reaction model in comparison to the performance benefits gained by model simplifications. We provide some observations regarding the use of these global reaction models in a purely non-premixed combustion setting. A preliminary flamelet generated manifold is presented to be explored in future work.},
	urldate = {2024-05-29},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-0161},
	author = {DeBoskey, Ryan D. and Kessler, David A. and Bojko, Brian T. and Johnson, Ryan F. and Goodwin, Gabriel B.},
	year = {2023},
	note = {\_eprint: https://arc.aiaa.org/doi/pdf/10.2514/6.2023-0161},
}

View Video Presentation: https://doi.org/10.2514/6.2023-0161.vidWe describe the differences in the combustion behavior within a model opposed-flow solid fuel burner produced by three different chemical reaction models: a two-step global mechanism, a six-step global mechanism, and a pressure-comprehensive skeletal model, all of which assume butadiene as the primary fuel source. Details of the implementation of these models in conjunction with an equilibrium interfacial pyrolysis model for the solid gas phase change process are provided. Of particular interest are the differences in flame structure and dynamics predicted by each reaction model in comparison to the performance benefits gained by model simplifications. We provide some observations regarding the use of these global reaction models in a purely non-premixed combustion setting. A preliminary flamelet generated manifold is presented to be explored in future work.

@inproceedings{maier2023,
	title = {Development of {Physical} and {Numerical} {Nonequilibrium} {Modeling} {Capabilities} within the {SU2}-{NEMO} {Code}},
	doi = {10.2514/6.2023-3488},
	publisher = {AIAA Paper 2023-3488},
	author = {Maier, Walter T. and Needels, Jacob T. and Alonso, Juan J and Morgado, Fabio and Garbacz, Catarina and Fossati, Marco and Tumuklu, Ozgur and Hanquist, Kyle M},
	year = {2023},
	keywords = {own},
}

@inproceedings{thompson2023,
	title = {Economical {Third}-{Order} {Methods} for {Accurate} {Surface} {Heating} {Predictions} on {Simplex} {Element} {Meshes}},
	doi = {10.2514/6.2023-2629},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-2629.vidA node-centered, edge-based finite volume discretization of the compressible Navier-Stokes equations is presented with the heat flux reformulated as a first-order system. A dissipation vector is derived for the reformulated system, such that the heat flux can be upgraded to O(h{\textasciicircum}3) on simplex element meshes in the same fashion as the inviscid fluxes. The method of manufactured solutions is used to demonstrate this uniform order property in heat flux. This new system is shown to efficiently produce accurate surface heating predictions in hypersonic flow using an anisotropic simplex element mesh, achieving O(h{\textasciicircum}3) accuracy at relatively low computational cost compared to similar methods.},
	urldate = {2024-05-27},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-2629},
	author = {Thompson, Kyle B. and Nishikawa, Hiroaki and Padway, Emmett},
	year = {2023},
}

View Video Presentation: https://doi.org/10.2514/6.2023-2629.vidA node-centered, edge-based finite volume discretization of the compressible Navier-Stokes equations is presented with the heat flux reformulated as a first-order system. A dissipation vector is derived for the reformulated system, such that the heat flux can be upgraded to O(h\textasciicircum3) on simplex element meshes in the same fashion as the inviscid fluxes. The method of manufactured solutions is used to demonstrate this uniform order property in heat flux. This new system is shown to efficiently produce accurate surface heating predictions in hypersonic flow using an anisotropic simplex element mesh, achieving O(h\textasciicircum3) accuracy at relatively low computational cost compared to similar methods.

@article{gollapudi2023,
	title = {Realization of electron transpiration cooling: {LaB6} heated by a plasma glow},
	volume = {123},
	issn = {0003-6951, 1077-3118},
	shorttitle = {Realization of electron transpiration cooling},
	doi = {10.1063/5.0163560},
	abstract = {Electron transpiration cooling has previously been predicted to be an alternative cooling mechanism for leading edges of aerospace platforms traveling at extreme velocities, where thermoelectric materials shaped as leading edges manage heat loads. Here, thermo-electron emitting LaB6 ceramics with blunt edges were placed between two conical-shaped electrodes, and a plasma glow was ignited to heat the sample. Analysis of current–voltage (I–V) curves demonstrated that insertion of LaB6 into the plasma column resulted in an increase in the electron density of the plasma, evidencing thermally stimulated electron emission. With increasing sample temperature to 1200 K, Dne increased by \$4 Â 1010 \#/cm3, the electron temperature (Te) decreased from \$8 eV (1000 K) to 2.5 eV, and the emission begins to appear to become space charge-limited. Richardson’s analysis of the temperature dependence of the electron emission in the region of ion saturation, yielded an activation energy consistent with the work function of LaB6. Modulation of the LaB6 surface temperature (DT ¼ 10 K) and the plasma current (DI ¼ 70 lA) under electric voltage (80 V) applied between the sample and current probe was demonstrated. The results show for the first time the feasibility of electron transpiration cooling effects under plasma conditions similar to that of aerothermal environments.},
	language = {en},
	number = {10},
	urldate = {2023-10-30},
	journal = {Applied Physics Letters},
	author = {Gollapudi, Sreenivasulu and Suchicital, Carlos and Li, Jie-Fang and Viehland, D.},
	month = sep,
	year = {2023},
	pages = {101602},
}

Electron transpiration cooling has previously been predicted to be an alternative cooling mechanism for leading edges of aerospace platforms traveling at extreme velocities, where thermoelectric materials shaped as leading edges manage heat loads. Here, thermo-electron emitting LaB6 ceramics with blunt edges were placed between two conical-shaped electrodes, and a plasma glow was ignited to heat the sample. Analysis of current–voltage (I–V) curves demonstrated that insertion of LaB6 into the plasma column resulted in an increase in the electron density of the plasma, evidencing thermally stimulated electron emission. With increasing sample temperature to 1200 K, Dne increased by $4 Â 1010 #/cm3, the electron temperature (Te) decreased from $8 eV (1000 K) to 2.5 eV, and the emission begins to appear to become space charge-limited. Richardson’s analysis of the temperature dependence of the electron emission in the region of ion saturation, yielded an activation energy consistent with the work function of LaB6. Modulation of the LaB6 surface temperature (DT ¼ 10 K) and the plasma current (DI ¼ 70 lA) under electric voltage (80 V) applied between the sample and current probe was demonstrated. The results show for the first time the feasibility of electron transpiration cooling effects under plasma conditions similar to that of aerothermal environments.

@article{moritz2023,
	title = {Thermionic emission of a tungsten surface in high heat flux plasma: {PIC} simulations},
	volume = {30},
	shorttitle = {Thermionic emission of a tungsten surface in high heat flux plasma},
	doi = {10.1063/5.0160767},
	abstract = {The surface temperature of a tungsten surface facing hot hydrogen plasma is evaluated, thanks to 1d/3v particle-in-cell simulations in floating wall conditions. At each iteration, the plasma heat flux to the cathode is equalized with the outgoing one, which is due to thermionic emission, surface radiation, and heat conduction through the wall. The thermal conductivity is chosen within the range 35–160 W mÀ1 KÀ1 in the different simulations in order to take into account the surface condition. A transition from a cold temperature surface to a hot one arises for a critical thermal conductivity, whose value depends on the plasma parameters. This transition is very abrupt and leads to a space charge limited regime where the thermionic current penetrating the plasma has reached its maximal value and is about three times the Bohm current. Changing the initial conditions in the code, more particularly, the timing of electron emission, can lead to a very different final surface temperature. This history effect and the associated hysteresis are evidenced by means of fluid calculations, which are in a good agreement with the simulation results as well as with previous experimental measurements.},
	language = {en},
	number = {8},
	urldate = {2024-04-05},
	journal = {Physics of Plasmas},
	author = {Moritz, J. and Heuraux, S. and Lemoine, N. and Lesur, M. and Gravier, E. and Brochard, F. and Marot, L. and Hiret, P.},
	month = aug,
	year = {2023},
}

The surface temperature of a tungsten surface facing hot hydrogen plasma is evaluated, thanks to 1d/3v particle-in-cell simulations in floating wall conditions. At each iteration, the plasma heat flux to the cathode is equalized with the outgoing one, which is due to thermionic emission, surface radiation, and heat conduction through the wall. The thermal conductivity is chosen within the range 35–160 W mÀ1 KÀ1 in the different simulations in order to take into account the surface condition. A transition from a cold temperature surface to a hot one arises for a critical thermal conductivity, whose value depends on the plasma parameters. This transition is very abrupt and leads to a space charge limited regime where the thermionic current penetrating the plasma has reached its maximal value and is about three times the Bohm current. Changing the initial conditions in the code, more particularly, the timing of electron emission, can lead to a very different final surface temperature. This history effect and the associated hysteresis are evidenced by means of fluid calculations, which are in a good agreement with the simulation results as well as with previous experimental measurements.

@article{tumuklu2023c,
	title = {Temporal characteristics of hypersonic flows over a double wedge with {Reynolds} number},
	volume = {35},
	doi = {10.1063/5.0169648},
	abstract = {Laminar hypersonic flows at Mach 7.10 with unit Reynolds numbers of    5.2 ×   10 4 ,   1.04 ×   10 5, and    4.14 ×   10 5 m−1 over a 30°/55° double-wedge configuration were studied to investigate the spatial–temporal characteristics of the flow in a time-accurate manner. Close comparisons were made between previous kinetic and current continuum approaches to test the validity of the continuum assumption, especially considering the presence of large gradients associated with shock–shock and shock–boundary layer interactions, as well as spanwise instabilities. Previous results from direct simulation Monte Carlo, which inherently predicts rarefied effects such as velocity slip and temperature jumps, were found to be in very close agreement with the current work, even for the lowest Reynolds number. The impact of velocity slip and temperature jumps on flow and surface parameters was investigated, and comparisons were made with a no-slip and constant temperature wall model. The temporal and spatial variation of two- and three-dimensional flows were thoroughly investigated using two-dimensional (2D), three-dimensional (3D) periodic sidewall boundary conditions, and a full 3D configuration consistent with existing experimental data. Close comparisons among the 2D and 3D cases were made. The characteristics of 2D periodic oscillations were reported for the moderate Reynolds number case for the first time. The presence of spanwise instabilities, even at a relatively low free stream pressure of about 100 Pa, establishes that the flow field depends on spanwise effects and is fully 3D. High-fidelity numerical schlieren videos captured strong spanwise oscillations for 3D configurations.},
	number = {10},
	journal = {Physics of Fluids},
	author = {Tumuklu, Ozgur and Hanquist, Kyle M.},
	month = oct,
	year = {2023},
	keywords = {own},
}

Laminar hypersonic flows at Mach 7.10 with unit Reynolds numbers of 5.2 × 10 4 ,   1.04 × 10 5, and 4.14 × 10 5 m−1 over a 30°/55° double-wedge configuration were studied to investigate the spatial–temporal characteristics of the flow in a time-accurate manner. Close comparisons were made between previous kinetic and current continuum approaches to test the validity of the continuum assumption, especially considering the presence of large gradients associated with shock–shock and shock–boundary layer interactions, as well as spanwise instabilities. Previous results from direct simulation Monte Carlo, which inherently predicts rarefied effects such as velocity slip and temperature jumps, were found to be in very close agreement with the current work, even for the lowest Reynolds number. The impact of velocity slip and temperature jumps on flow and surface parameters was investigated, and comparisons were made with a no-slip and constant temperature wall model. The temporal and spatial variation of two- and three-dimensional flows were thoroughly investigated using two-dimensional (2D), three-dimensional (3D) periodic sidewall boundary conditions, and a full 3D configuration consistent with existing experimental data. Close comparisons among the 2D and 3D cases were made. The characteristics of 2D periodic oscillations were reported for the moderate Reynolds number case for the first time. The presence of spanwise instabilities, even at a relatively low free stream pressure of about 100 Pa, establishes that the flow field depends on spanwise effects and is fully 3D. High-fidelity numerical schlieren videos captured strong spanwise oscillations for 3D configurations.

@article{baluckram2023,
	title = {Simulation of {Oxygen} {Chemical} {Kinetics} {Behind} {Incident} and {Reflected} {Shocks} via {Master} {Equation}},
	volume = {37},
	issn = {0887-8722},
	url = {https://doi.org/10.2514/1.T6522},
	doi = {10.2514/1.T6522},
	abstract = {A model for simulating postshock conditions using only state-resolved kinetic data of ab initio accuracy is presented. The quasi-classical trajectory method is used to compute a vibrational-specific kinetic database that describes internal energy transfer and dissociation in a nonionizing oxygen mixture. The kinetic database is implemented in a system of master equations and coupled to conservation laws to simulate a series of conditions, including zero-dimensional adiabatic reservoir, one-dimensional postincident, and one-dimensional postreflected shock relaxation. The present results are in excellent agreement with temperature profiles produced by the direct molecular simulation method at a fraction of cost. For the first time, the state-resolved model is applied to model relaxation behind a reflected shock passing through a thermally nonequilibrium gas. Model validation is made via comparisons to the experiments of Ibraguimova et al. (Journal of Chemical Physics, Vol. 139, No. 3, 2013, Paper 034317) and Streicher et al. (Physics of Fluids, Vol. 33, No. 5, 2021, Paper 056107). It is shown that neglecting relaxation in the postincident shock region may lead to nonnegligible errors in determining initial postreflected shock translational and vibrational temperatures, particularly in cases where the test gas is not diluted with an inert species.},
	number = {1},
	urldate = {2024-02-29},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Baluckram, Varishth T. and Fangman, Alexander J. and Andrienko, Daniil A.},
	year = {2023},
	pages = {198--212},
}

A model for simulating postshock conditions using only state-resolved kinetic data of ab initio accuracy is presented. The quasi-classical trajectory method is used to compute a vibrational-specific kinetic database that describes internal energy transfer and dissociation in a nonionizing oxygen mixture. The kinetic database is implemented in a system of master equations and coupled to conservation laws to simulate a series of conditions, including zero-dimensional adiabatic reservoir, one-dimensional postincident, and one-dimensional postreflected shock relaxation. The present results are in excellent agreement with temperature profiles produced by the direct molecular simulation method at a fraction of cost. For the first time, the state-resolved model is applied to model relaxation behind a reflected shock passing through a thermally nonequilibrium gas. Model validation is made via comparisons to the experiments of Ibraguimova et al. (Journal of Chemical Physics, Vol. 139, No. 3, 2013, Paper 034317) and Streicher et al. (Physics of Fluids, Vol. 33, No. 5, 2021, Paper 056107). It is shown that neglecting relaxation in the postincident shock region may lead to nonnegligible errors in determining initial postreflected shock translational and vibrational temperatures, particularly in cases where the test gas is not diluted with an inert species.

@misc{morgado2023,
	title = {Hypersonic {Testing} \& {Digital} {Twins}},
	author = {Morgado, Fábio and Garbacz, Catarina and Tumuklu, Ozgur and Needels, Jacob T. and Maier, Walter T. and Alonso, Juan J and Hanquist, Kyle M. and Fossati, Marco},
	year = {2023},
	keywords = {own, presentation},
}

@misc{hanquist2023e,
	address = {Turbulence Analysis and Simulation Center, Lawrence Livermore National Laboratory},
	type = {Invited {Seminar}},
	title = {Modeling of {Real} {Gas} {Effects} in {Hypersonic} {Flows}},
	author = {Hanquist, Kyle M.},
	year = {2023},
	keywords = {invited, own},
}

@misc{hanquist2023d,
	address = {Aerothermodynamics Branch, NASA Ames},
	type = {Invited {Seminar}},
	title = {Investigating {High}-{Enthalpy} {Effects} using {Computational} {Modeling}},
	author = {Hanquist, Kyle M.},
	year = {2023},
	keywords = {invited, own},
}

@misc{hanquist2023b,
	address = {Salt Lake City, UT},
	type = {Invited {Presentation}},
	title = {Investigating {High}-{Enthalpy} {Effects} in {High}-{Speed} {Flows} using {Open}-{Source} {Computational} {Modeling}},
	author = {Hanquist, Kyle M.},
	year = {2023},
	keywords = {invited, own},
}

@misc{hanquist2023c,
	address = {Department of Aerospace Engineering \& Mechanics, University of Minnesota},
	type = {Invited {Seminar}},
	title = {Investigating high-enthalpy hypersonic effects using modeling and simulation},
	author = {Hanquist, Kyle M.},
	year = {2023},
	keywords = {invited, own},
}

@inproceedings{kuppa2023,
	title = {Reduced {Order} {Modelling} and {Quantification} of {Uncertainty} in {Non} {Equilibrium} {Flows}},
	doi = {10.2514/6.2023-3331},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-3331.vidThis study investigates uncertainty propagation and sensitivity analysis of state-specific dissociation and excitation rate coefficients in the context of macroscopic quantities of interest such as species mole fraction evolution and quasi-steady-state (QSS) rate coefficient. To accomplish this, an isothermal isochoric zero-dimensional chemical reactor is solved for various bath conditions. To handle the computational complexity of the master equations, three different coarse-graining methods are utilized: a 200-bin energy-based lumping model, a 3-bin energy-based lumping model, and a 10-bin spectral clustering-based model. The results show that while the uncertainty propagation is sensitive to the type of coarse-graining, the spectral clustering method produces the least model error when compared to the other coarse-grained models employed. Moreover, when an uncertainty factor of 5 is applied to the state-specific dissociation rate coefficients, it leads to an approximate ± 10\% uncertainty range around the nominal values of the QSS rate coefficient. The sensitivity analysis conducted using the 200-bin model reveals that the most influential factor affecting the QSS rate coefficient and dissociation time is the mono-quantum vibrational excitation from low-lying levels. Additionally, at low temperatures, the high-lying dissociation rate coefficients contribute significantly to the uncertainty of the studied quantities, while at high temperatures, the dissociation from low to moderate-lying vibrational energy states plays a crucial role. These findings underscore the critical role played by vibrational excitation in determining the behavior of reactive systems at different temperature regimes.},
	urldate = {2023-08-08},
	booktitle = {{AIAA} {AVIATION} 2023 {Forum}},
	publisher = {AIAA Paper 2023-3331},
	author = {Kuppa, Mridula and Singh, Narendra and Rostkowski, Przemyslaw and Ghanem, Roger and Panesi, Marco},
	year = {2023},
}

View Video Presentation: https://doi.org/10.2514/6.2023-3331.vidThis study investigates uncertainty propagation and sensitivity analysis of state-specific dissociation and excitation rate coefficients in the context of macroscopic quantities of interest such as species mole fraction evolution and quasi-steady-state (QSS) rate coefficient. To accomplish this, an isothermal isochoric zero-dimensional chemical reactor is solved for various bath conditions. To handle the computational complexity of the master equations, three different coarse-graining methods are utilized: a 200-bin energy-based lumping model, a 3-bin energy-based lumping model, and a 10-bin spectral clustering-based model. The results show that while the uncertainty propagation is sensitive to the type of coarse-graining, the spectral clustering method produces the least model error when compared to the other coarse-grained models employed. Moreover, when an uncertainty factor of 5 is applied to the state-specific dissociation rate coefficients, it leads to an approximate ± 10% uncertainty range around the nominal values of the QSS rate coefficient. The sensitivity analysis conducted using the 200-bin model reveals that the most influential factor affecting the QSS rate coefficient and dissociation time is the mono-quantum vibrational excitation from low-lying levels. Additionally, at low temperatures, the high-lying dissociation rate coefficients contribute significantly to the uncertainty of the studied quantities, while at high temperatures, the dissociation from low to moderate-lying vibrational energy states plays a crucial role. These findings underscore the critical role played by vibrational excitation in determining the behavior of reactive systems at different temperature regimes.

@inproceedings{chaudhry2023,
	title = {Parametric {Comparison} of the {Park} and {MMT} {Chemical} {Kinetics} {Models} with {Multiple} {Freestream} {Speeds}},
	doi = {10.2514/6.2023-3621},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-3621.vidThe Modified Marrone-Treanor (MMT) chemical kinetics model, developed using quantum chemistry data, is compared to the Park model for hypersonic blunt cones. A variety of flow configuration parameters are considered: nose radii between 1 and 10 cm, freestream altitudes between 0 and 70 km, and freestream speeds between 3 and 6 km/s. Consistent with previous work, lower altitude conditions are dominated by the dynamics of recombination and yield up to 30\% higher stagnation heating with Park than MMT, whereas higher altitudes are dominated by dissociation and yield up to 15\% lower heating with Park than MMT. Freestream speeds of 4 and 5 km/s exhibit the largest difference in stagnation-point heating due to the dominance of oxygen dissociation in these flows. Consistency between the present results and Fay and Riddell’s dissociation enthalpy is also demonstrated. This work describes the effect of gas-phase chemical kinetics on design-relevant flow configurations and the wide range of parameters considered can target experimental validation efforts.},
	urldate = {2023-08-08},
	booktitle = {{AIAA} {AVIATION} 2023 {Forum}},
	publisher = {AIAA Paper 2023-3621},
	author = {Chaudhry, Ross S. and Boyd, Iain D.},
	year = {2023},
	doi = {10.2514/6.2023-3621},
	note = {\_eprint: https://arc.aiaa.org/doi/pdf/10.2514/6.2023-3621},
}

View Video Presentation: https://doi.org/10.2514/6.2023-3621.vidThe Modified Marrone-Treanor (MMT) chemical kinetics model, developed using quantum chemistry data, is compared to the Park model for hypersonic blunt cones. A variety of flow configuration parameters are considered: nose radii between 1 and 10 cm, freestream altitudes between 0 and 70 km, and freestream speeds between 3 and 6 km/s. Consistent with previous work, lower altitude conditions are dominated by the dynamics of recombination and yield up to 30% higher stagnation heating with Park than MMT, whereas higher altitudes are dominated by dissociation and yield up to 15% lower heating with Park than MMT. Freestream speeds of 4 and 5 km/s exhibit the largest difference in stagnation-point heating due to the dominance of oxygen dissociation in these flows. Consistency between the present results and Fay and Riddell’s dissociation enthalpy is also demonstrated. This work describes the effect of gas-phase chemical kinetics on design-relevant flow configurations and the wide range of parameters considered can target experimental validation efforts.

@inproceedings{torres2023,
	title = {Implementation of new multi-temperature nonequilibrium air chemistry model for {CFD} based on first-principles calculations},
	doi = {10.2514/6.2023-3489},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-3489.vidIn this paper we present recent updates to the Modified Marrone-Treanor thermochemical nonequilibrium model for five-species air, originally developed for computational fluid dynamics calculations of hypersonic flows. The updated (2023) version of the chemistry model used here employs new high-fidelity kinetic rate data for all air reactions (including oxygen/nitrogen/nitric oxide dissociation and Zeldovich exchange reactions) derived from quasi-classical trajectory calculations on {\textbackslash}emphab initio potential energy surfaces. We first verify the updated chemistry model against first-principles Direct Molecular Simulations by studying nonequilibrium reacting air mixtures in space-homogeneous heat baths representative of high-temperature post-shock conditions. Once validated in these simple scenarios, we employ the model in larger-scale computational fluid dynamics studies of hypersonic flow around a geometry representing a generic flight vehicle. There we compare the Modified Marrone-Treanor predictions against the standard nonequilibrium model by Park. This research demonstrates how complex nonequilibrium chemistry induced by hypersonic flight can be incorporated into accurate and efficient models for large-scale computational fluid dynamics simulations.},
	urldate = {2023-08-08},
	booktitle = {{AIAA} {AVIATION} 2023 {Forum}},
	publisher = {AIAA Paper 2023-3489},
	author = {Torres, Erik and Gross, Thomas and Schwartzentruber, Thomas E.},
	year = {2023},
}

View Video Presentation: https://doi.org/10.2514/6.2023-3489.vidIn this paper we present recent updates to the Modified Marrone-Treanor thermochemical nonequilibrium model for five-species air, originally developed for computational fluid dynamics calculations of hypersonic flows. The updated (2023) version of the chemistry model used here employs new high-fidelity kinetic rate data for all air reactions (including oxygen/nitrogen/nitric oxide dissociation and Zeldovich exchange reactions) derived from quasi-classical trajectory calculations on \emphab initio potential energy surfaces. We first verify the updated chemistry model against first-principles Direct Molecular Simulations by studying nonequilibrium reacting air mixtures in space-homogeneous heat baths representative of high-temperature post-shock conditions. Once validated in these simple scenarios, we employ the model in larger-scale computational fluid dynamics studies of hypersonic flow around a geometry representing a generic flight vehicle. There we compare the Modified Marrone-Treanor predictions against the standard nonequilibrium model by Park. This research demonstrates how complex nonequilibrium chemistry induced by hypersonic flight can be incorporated into accurate and efficient models for large-scale computational fluid dynamics simulations.

@inproceedings{riley2023,
	title = {Design of {Aerothermoelastic} {Experiments} in the {AFRL} {Mach} 6 {High} {Reynolds} {Number} {Facility}},
	doi = {10.2514/6.2023-0948},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2023-0948.vidAn experiment was recently conducted in the Air Force Research Laboratory Mach 6 High Reynolds Number Facility exploring the aerothermoelastic response of metallic panels with thicknesses of 381, 508, and 635 μm. Simultaneous, full-field measurements of the panel response were made using stereo digital image correlation, an infrared camera, and a shadowgraph system. Each panel was also instrumented with strain gages and thermocouples. Aeroelastic simulations were carried out to identify the freestream conditions and loading required to exhibit large-amplitude, oscillatory response. Key features of the model design including; an increased length, a pressurized and controllable cavity, and angle of attack variation made it possible to observe panel flutter. Sustained and repeatable large-amplitude oscillations were observed for each panel thickness at different freestream conditions.},
	urldate = {2023-08-03},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-0948},
	author = {Riley, Zachary B. and Perez, Ricardo and Brouwer, Kirk R.},
	year = {2023},
	note = {\_eprint: https://arc.aiaa.org/doi/pdf/10.2514/6.2023-0948},
}

View Video Presentation: https://doi.org/10.2514/6.2023-0948.vidAn experiment was recently conducted in the Air Force Research Laboratory Mach 6 High Reynolds Number Facility exploring the aerothermoelastic response of metallic panels with thicknesses of 381, 508, and 635 μm. Simultaneous, full-field measurements of the panel response were made using stereo digital image correlation, an infrared camera, and a shadowgraph system. Each panel was also instrumented with strain gages and thermocouples. Aeroelastic simulations were carried out to identify the freestream conditions and loading required to exhibit large-amplitude, oscillatory response. Key features of the model design including; an increased length, a pressurized and controllable cavity, and angle of attack variation made it possible to observe panel flutter. Sustained and repeatable large-amplitude oscillations were observed for each panel thickness at different freestream conditions.

@inproceedings{tumuklu2023a,
	title = {Unsteadiness of hypersonic flows over a double wedge},
	doi = {10.2514/6.2023-0860},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-0860},
	author = {Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2023},
	keywords = {own},
}

@inproceedings{liza2023,
	title = {Nonequilibrium {Effects} on {Aero}-{Optics} in {Hypersonic} {Flows}},
	doi = {10.2514/6.2023-3736},
	booktitle = {{AIAA} {AVIATION}},
	publisher = {AIAA Paper 2023-3736},
	author = {Liza, Martin E. and Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2023},
	keywords = {own},
}

@inproceedings{oveissi2023,
	title = {Learning-based {Adaptive} {Thrust} {Regulation} of {Solid} {Fuel} {Ramjet}},
	doi = {10.2514/6.2023-2533},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-2533},
	author = {Oveissi, Parham and Trivedi, Arjun and Goel, Ankit and Tumuklu, Ozgur and Hanquist, Kyle M. and Farahmandi, Alireza and Philbrick, Douglas},
	year = {2023},
	keywords = {own},
}

@misc{hanquist2023,
	address = {Program in Applied Math, University of Arizona},
	type = {Invited {Seminar}},
	title = {Importance of {Modeling} to {Hypersonic} {Flight}},
	author = {Hanquist, Kyle M.},
	year = {2023},
	keywords = {invited, own},
}

@inproceedings{wang2023,
	title = {High {Temperature} {Gladstone}-{Dale} {Coefficient} {Measurements} in a {Free}-{Piston} {Shock} {Tube}},
	doi = {10.2514/6.2023-0225},
	urldate = {2023-01-27},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-0225},
	author = {Wang, Gwendolyn and Daniel, Kyle and Lynch, Kyle P. and Guildenbecher, Daniel R. and Mazumdar, Yi C.},
	year = {2023},
}

@inproceedings{tumuklu2023,
	title = {Development of a hybrid particle-continuum solver for studying pluma expansion into rarefied flows},
	doi = {10.2514/6.2023-0073},
	booktitle = {{AIAA} {SCITECH} 2023 {Forum}},
	publisher = {AIAA Paper 2023-0073},
	author = {Tumuklu, Ozgur and Bellan, Josette R. and Hanquist, Kyle M.},
	year = {2023},
	keywords = {own},
}

@inproceedings{fedeli2022,
	title = {Pushing the {Frontier} in the {Design} of {Laser}-{Based} {Electron} {Accelerators} with {Groundbreaking} {Mesh}-{Refined} {Particle}-{In}-{Cell} {Simulations} on {Exascale}-{Class} {Supercomputers}},
	doi = {10.1109/SC41404.2022.00008},
	abstract = {(150 word max) We present a first-of-kind mesh-refined (MR) massively parallel Particle-In-Cell (PIC) code for kinetic plasma simulations optimized on the Frontier, Fugaku, Summit, and Perlmutter supercomputers. Major innovations, implemented in the WarpX PIC code, include: (i) a three level parallelization strategy that demonstrated performance portability and scaling on millions of A64FX cores and tens of thousands of AMD and Nvidia GPUs (ii) a groundbreaking mesh refinement capability that provides between 1.5 x to 4 x savings in computing requirements on the science case reported in this paper, (iii) an efficient load balancing strategy between multiple MR levels. The MR PIC code enabled 3D simulations of laser-matter interactions on Frontier, Fugaku, and Summit, which have so far been out of the reach of standard codes. These simulations helped remove a major limitation of compact laser-based electron accelerators, which are promising candidates for next generation high-energy physics experiments and ultra-high dose rate FLASH radiotherapy.},
	urldate = {2025-10-28},
	booktitle = {{SC22}: {International} {Conference} for {High} {Performance} {Computing}, {Networking}, {Storage} and {Analysis}},
	author = {Fedeli, Luca and Huebl, Axel and Boillod-Cerneux, France and Clark, Thomas and Gott, Kevin and Hillairet, Conrad and Jaure, Stephan and Leblanc, Adrien and Lehe, Rémi and Myers, Andrew and Piechurski, Christelle and Sato, Mitsuhisa and Zaim, Neïl and Zhang, Weiqun and Vay, Jean-Luc and Vincenti, Henri},
	month = nov,
	year = {2022},
	note = {ISSN: 2167-4337},
	keywords = {Adaptive mesh refinement, Codes, Computational modeling, Electron accelerators, Exascale computing, High performance computing, Particle-In-Cell method, Plasma accelerators, Solid modeling, Supercomputers, Technological innovation, Three-dimensional displays, high-field science, laser-matter interaction},
	pages = {1--12},
}

(150 word max) We present a first-of-kind mesh-refined (MR) massively parallel Particle-In-Cell (PIC) code for kinetic plasma simulations optimized on the Frontier, Fugaku, Summit, and Perlmutter supercomputers. Major innovations, implemented in the WarpX PIC code, include: (i) a three level parallelization strategy that demonstrated performance portability and scaling on millions of A64FX cores and tens of thousands of AMD and Nvidia GPUs (ii) a groundbreaking mesh refinement capability that provides between 1.5 x to 4 x savings in computing requirements on the science case reported in this paper, (iii) an efficient load balancing strategy between multiple MR levels. The MR PIC code enabled 3D simulations of laser-matter interactions on Frontier, Fugaku, and Summit, which have so far been out of the reach of standard codes. These simulations helped remove a major limitation of compact laser-based electron accelerators, which are promising candidates for next generation high-energy physics experiments and ultra-high dose rate FLASH radiotherapy.

@inproceedings{nastac_improved_2022,
	address = {San Diego, CA \& Virtual},
	title = {Improved {Heat} {Transfer} {Prediction} for {High}-{Speed} {Flows} over {Blunt} {Bodies} using {Adaptive} {Mixed}-{Element} {Unstructured} {Grids}},
	isbn = {978-1-62410-631-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2022-0111},
	doi = {10.2514/6.2022-0111},
	language = {en},
	urldate = {2025-03-04},
	booktitle = {{AIAA} {SCITECH} 2022 {Forum}},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Nastac, Gabriel and Tramel, Robert W. and Nielsen, Eric J.},
	month = jan,
	year = {2022},
}

@misc{electron2022,
	title = {Electron {Payload} {User}'s {Guide}},
	url = {https://www.rocketlabusa.com/assets/Uploads/Electron-Payload-User-Guide-7.0.pdf},
	month = nov,
	year = {2022},
}

@misc{vulcan2022,
	title = {Vulcan {Centaur}},
	url = {https://www.ulalaunch.com/docs/default-source/rockets/vulcancentaur.pdf?sfvrsn=10d7f58f_2},
	journal = {Vulcan Centaur},
	year = {2022},
}

@inproceedings{Miller2022,
	address = {Reston, Virginia},
	title = {Aero-optical distortions of turbulent boundary layers: {Hypersonic} {DNS}},
	isbn = {978-1-62410-631-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2022-0056},
	doi = {10.2514/6.2022-0056},
	booktitle = {{AIAA} {SCITECH} 2022 forum},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Miller, Nathan E. and Lynch, Kyle P. and Gordeyev, Stanislav and Guildenbecher, Daniel R. and Duan, Lian and Wagnild, Ross M.},
	month = jan,
	year = {2022},
}

@inproceedings{needels2022,
	title = {Sensitivity {Analysis} of {Gas}-{Surface} {Modeling} in {Nonequilibrium} {Flows}},
	doi = {10.2514/6.2022-1636},
	booktitle = {{AIAA} {SCITECH} 2022 {Forum}},
	publisher = {AIAA Paper 2022-1636},
	author = {Needels, Jacob T. and Düzel, Ümran and Hanquist, Kyle M. and Alonso, Juan J.},
	year = {2022},
	keywords = {own},
}

@article{bojan2022,
	title = {Fluid/{Structure} {Interaction} of {Cantilevered} {Plate} in {Supersonic} {Separated} {Flow}},
	volume = {60},
	issn = {0001-1452},
	doi = {10.2514/1.J061883},
	abstract = {The fluid-structure interaction of a cantilevered plate geometry in Mach 2 flow was studied experimentally to assess the effects of structural compliance on the surrounding flowfield. The test geometry, representative of a compliant control surface, consists of an overhanging plate that extends past the edge of a backward-facing step to create a separated region in the flow. This allowed for the study of recirculation effects and unsteady pressure forcing on the cantilevered plate without shock/boundary-layer interactions that would be present if the plate were inclined to the flow. Rigid and compliant test articles were studied to capture the fluid response with and without structural deformation. Schlieren photography and particle image velocimetry showed that under the unsteady conditions during startup of the wind tunnel the flexible plate exhibited a highly dynamic oscillatory response with frequencies similar to its natural vibration response. Under steady, started supersonic flow conditions, the flexible cantilever exhibited smaller oscillations around a mean deflection of two plate thicknesses. Oil flow visualization revealed nontrivial three-dimensionality of the test section flowfield. Modal decomposition of stereo digital image correlation measurements demonstrated that the distinct frequencies present in the flexible plate’s response consistently correspond to the same mode shapes.},
	number = {12},
	urldate = {2024-06-18},
	journal = {AIAA Journal},
	author = {Bojan, Griffin K. and Dutton, J. Craig and Elliott, Gregory S.},
	year = {2022},
	pages = {6726--6738},
}

The fluid-structure interaction of a cantilevered plate geometry in Mach 2 flow was studied experimentally to assess the effects of structural compliance on the surrounding flowfield. The test geometry, representative of a compliant control surface, consists of an overhanging plate that extends past the edge of a backward-facing step to create a separated region in the flow. This allowed for the study of recirculation effects and unsteady pressure forcing on the cantilevered plate without shock/boundary-layer interactions that would be present if the plate were inclined to the flow. Rigid and compliant test articles were studied to capture the fluid response with and without structural deformation. Schlieren photography and particle image velocimetry showed that under the unsteady conditions during startup of the wind tunnel the flexible plate exhibited a highly dynamic oscillatory response with frequencies similar to its natural vibration response. Under steady, started supersonic flow conditions, the flexible cantilever exhibited smaller oscillations around a mean deflection of two plate thicknesses. Oil flow visualization revealed nontrivial three-dimensionality of the test section flowfield. Modal decomposition of stereo digital image correlation measurements demonstrated that the distinct frequencies present in the flexible plate’s response consistently correspond to the same mode shapes.

@article{kumarreddysirigiri2022,
	series = {International {Conference} on {Materials}, {Processing} \& {Characterization} (13th {ICMPC})},
	title = {A review on {Johnson} {Cook} material model},
	volume = {62},
	doi = {10.1016/j.matpr.2022.04.279},
	abstract = {To design and optimise process parameters in the metal forming industry, it is necessary to have a consistent and realistic representation of material behaviour where strain, strain rate, and temperature have an effect on the material flow stress. This paper examines various approaches that are employed in calculating the Johnson Cook material constants. Split Hopkinson-bar methodology and universal tensile tests were used to determine the material constants related to Johnson Cook material and failure models. These models were used in numerical simulations to facilitate design optimization and reduce experimentation costs. Johnson Cook material models were employed in various simulation software’s like ABAQUS, LS-DYNA, and DEFORM 3D to simulate metal turning, milling, and forming operations.},
	urldate = {2024-06-12},
	journal = {Materials Today: Proceedings},
	author = {Kumar Reddy Sirigiri, Vasu and Yadav Gudiga, Vinith and Shankar Gattu, Uday and Suneesh, G. and Mohan Buddaraju, Krishna},
	month = jan,
	year = {2022},
	keywords = {Deformation, Identification method, Johnson Cook failure model, Johnson Cook model, Numerical Simulation},
	pages = {3450--3456},
}

To design and optimise process parameters in the metal forming industry, it is necessary to have a consistent and realistic representation of material behaviour where strain, strain rate, and temperature have an effect on the material flow stress. This paper examines various approaches that are employed in calculating the Johnson Cook material constants. Split Hopkinson-bar methodology and universal tensile tests were used to determine the material constants related to Johnson Cook material and failure models. These models were used in numerical simulations to facilitate design optimization and reduce experimentation costs. Johnson Cook material models were employed in various simulation software’s like ABAQUS, LS-DYNA, and DEFORM 3D to simulate metal turning, milling, and forming operations.

@inproceedings{vatansever2022,
	title = {A {Parametric} {Study} for {Kinetic} {Modeling} of {Emissive} {Sheaths} {Using} {Electrostatic} {Particle}-in-{Cell} {Method}},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2022-3361},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2022-3361.vidA one-dimensional collisionless space charge limited (SCL) sheath is solved by using electro-static Particle-in-cell (PIC) method. We conduct a parametric study with different plasma conditions to understand the emissive nature of SCL sheaths and electron transpiration cooling (ETC) of the surface in high-speed flows. It is seen that potential profile along a 1-D plasma is sensitive to changes of the ion to electron mass ratio (mi/me), the electron emission temperature (Temit), the number of emitted particles (Nemit) and length of the plasma slab (L). We observe that the emitted electrons with higher energies escape the SCL sheath more easily but others are trapped within the SCL sheath. The thermionic emission from the emitting wall increases with increased ion to electron mass ratio and electron emission temperature but becomes less when the length of plasma is increased.},
	urldate = {2024-04-12},
	booktitle = {{AIAA} {AVIATION} 2022 {Forum}},
	publisher = {AIAA Paper 2022-3361},
	author = {Vatansever, Davut and Nuwal, Nakul and Levin, Deborah A.},
	year = {2022},
}

View Video Presentation: https://doi.org/10.2514/6.2022-3361.vidA one-dimensional collisionless space charge limited (SCL) sheath is solved by using electro-static Particle-in-cell (PIC) method. We conduct a parametric study with different plasma conditions to understand the emissive nature of SCL sheaths and electron transpiration cooling (ETC) of the surface in high-speed flows. It is seen that potential profile along a 1-D plasma is sensitive to changes of the ion to electron mass ratio (mi/me), the electron emission temperature (Temit), the number of emitted particles (Nemit) and length of the plasma slab (L). We observe that the emitted electrons with higher energies escape the SCL sheath more easily but others are trapped within the SCL sheath. The thermionic emission from the emitting wall increases with increased ion to electron mass ratio and electron emission temperature but becomes less when the length of plasma is increased.

@article{beving2022,
	title = {How sheath properties change with gas pressure: modeling and simulation},
	volume = {31},
	issn = {0963-0252},
	shorttitle = {How sheath properties change with gas pressure},
	doi = {10.1088/1361-6595/ac85d7},
	abstract = {Particle-in-cell simulations are used to study how neutral pressure influences plasma properties at the sheath edge. The high rate of ion–neutral collisions at pressures above several mTorr are found to cause a decrease in the ion velocity at the sheath edge (collisional Bohm criterion), a decrease in the edge-to-center density ratio (h l factor), and an increase in the sheath width and sheath potential drop. A comparison with existing analytic models generally indicates favorable agreement, but with some distinctions. One is that models for the h l factor need to be made consistent with the collisional Bohm criterion. With this and similar corrections, a comprehensive fluid-based model of the plasma boundary transition is constructed that compares well with the simulation results.},
	language = {en},
	number = {8},
	urldate = {2024-04-24},
	journal = {Plasma Sources Science and Technology},
	author = {Beving, L. P. and Hopkins, M. M. and Baalrud, S. D.},
	month = aug,
	year = {2022},
	pages = {084009},
}

Particle-in-cell simulations are used to study how neutral pressure influences plasma properties at the sheath edge. The high rate of ion–neutral collisions at pressures above several mTorr are found to cause a decrease in the ion velocity at the sheath edge (collisional Bohm criterion), a decrease in the edge-to-center density ratio (h l factor), and an increase in the sheath width and sheath potential drop. A comparison with existing analytic models generally indicates favorable agreement, but with some distinctions. One is that models for the h l factor need to be made consistent with the collisional Bohm criterion. With this and similar corrections, a comprehensive fluid-based model of the plasma boundary transition is constructed that compares well with the simulation results.

@inproceedings{munafo2022,
	title = {A {Multi}-{Physics} {Modeling} {Framework} for {Inductively} {Coupled} {Plasma} {Wind} {Tunnels}},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2022-1011},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2022-1011.vidThis work discusses the development of a multi-physics modeling framework for Inductively Coupled Plasma (ICP) wind tunnels. As opposed to a monolithic approach, separate in-house solvers are considered to deal with the different parts of the complete model. The flowfield is modeled using hegel, a finite volume solver for non-equilibrium plasmas. The simulation of the electric field and the thermal Protection System (TPS) material sample is accomplished via a finite element solver and a finite volume solver (flux and pato, respectively). The three tools are coupled using the preCICE library. Results for a two-dimensional axi-symmetric ICP configuration are presented and discussed to illustrate the effectiveness of the proposed coupled approach for modeling ICP discharges along with material response and electromagnetic phenomena.},
	urldate = {2024-04-24},
	booktitle = {{AIAA} {SCITECH} 2022 {Forum}},
	publisher = {AIAA Paper 2022-2011},
	author = {Munafò, Alessandro and Chiodi, Robert and Kumar, Sanjeev and Maout, Vincent Le and Stephani, Kelly A. and Panerai, Francesco and Bodony, Daniel J. and Panesi, Marco},
	year = {2022},
}

View Video Presentation: https://doi.org/10.2514/6.2022-1011.vidThis work discusses the development of a multi-physics modeling framework for Inductively Coupled Plasma (ICP) wind tunnels. As opposed to a monolithic approach, separate in-house solvers are considered to deal with the different parts of the complete model. The flowfield is modeled using hegel, a finite volume solver for non-equilibrium plasmas. The simulation of the electric field and the thermal Protection System (TPS) material sample is accomplished via a finite element solver and a finite volume solver (flux and pato, respectively). The three tools are coupled using the preCICE library. Results for a two-dimensional axi-symmetric ICP configuration are presented and discussed to illustrate the effectiveness of the proposed coupled approach for modeling ICP discharges along with material response and electromagnetic phenomena.

@article{tomko2022,
	title = {Plasma-induced surface cooling},
	volume = {13},
	copyright = {2022 The Author(s)},
	issn = {2041-1723},
	doi = {10.1038/s41467-022-30170-5},
	abstract = {Plasmas are an indispensable materials engineering tool due to their unique ability to deliver a flux of species and energy to a surface. This energy flux serves to heat the surface out of thermal equilibrium with bulk material, thus enabling local physicochemical processes that can be harnessed for material manipulation. However, to-date, there have been no reports on the direct measurement of the localized, transient thermal response of a material surface exposed to a plasma. Here, we use time-resolved optical thermometry in-situ to show that the energy flux from a pulsed plasma serves to both heat and transiently cool the material surface. To identify potential mechanisms for this ‘plasma cooling,’ we employ time-resolved plasma diagnostics to correlate the photon and charged particle flux with the thermal response of the material. The results indicate photon-stimulated desorption of adsorbates from the surface is the most likely mechanism responsible for this plasma cooling.},
	language = {en},
	number = {1},
	urldate = {2024-04-10},
	journal = {Nature Communications},
	author = {Tomko, John A. and Johnson, Michael J. and Boris, David R. and Petrova, Tzvetelina B. and Walton, Scott G. and Hopkins, Patrick E.},
	month = may,
	year = {2022},
	keywords = {Applied physics, Characterization and analytical techniques, Materials for energy and catalysis, Plasma physics},
}

Plasmas are an indispensable materials engineering tool due to their unique ability to deliver a flux of species and energy to a surface. This energy flux serves to heat the surface out of thermal equilibrium with bulk material, thus enabling local physicochemical processes that can be harnessed for material manipulation. However, to-date, there have been no reports on the direct measurement of the localized, transient thermal response of a material surface exposed to a plasma. Here, we use time-resolved optical thermometry in-situ to show that the energy flux from a pulsed plasma serves to both heat and transiently cool the material surface. To identify potential mechanisms for this ‘plasma cooling,’ we employ time-resolved plasma diagnostics to correlate the photon and charged particle flux with the thermal response of the material. The results indicate photon-stimulated desorption of adsorbates from the surface is the most likely mechanism responsible for this plasma cooling.

@article{chourdakis2022,
	title = {{preCICE} v2: {A} sustainable and user-friendly coupling library},
	volume = {2},
	doi = {10.12688/openreseurope.14445.2},
	number = {51},
	journal = {Open Research Europe},
	author = {Chourdakis, G and Davis, K and Rodenberg, B and Schulte, M and Simonis, F and Uekermann, B and Abrams, G and Bungartz, HJ and Cheung Yau, L and Desai, I and Eder, K and Hertrich, R and Lindner, F and Rusch, A and Sashko, D and Schneider, D and Totounferoush, A and Volland, D and Vollmer, P and Koseomur, OZ},
	year = {2022},
}

@inproceedings{schmidt_kentucky_2022,
	title = {Kentucky {Re}-{Entry} {Universal} {Payload} {System} ({KRUPS}): {Overview} of flight test via high-altitude balloon},
	shorttitle = {Kentucky {Re}-{Entry} {Universal} {Payload} {System} ({KRUPS})},
	doi = {10.2514/6.2022-3729},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2022-3729.vidThe Kentucky Re-entry Universal Payload System (KRUPS) is a small re-entry capsule designed as a technology testbed. For its first incarnation, KRUPS has been designed to test Thermal Protection System (TPS) material and instrumentation. TPS are used to protect spacecraft, and its payload, from the extreme conditions of planetary entry. KRUPS has been developed at the University of Kentucky over the past 6 years. This specific launch aimed to produce system verification, software implementation, and launch qualifications, using an atmospheric balloon platform. The capsule released from the balloon in this experiment, was designed to transmit data using the Iridium satellite network. Recovery of the capsule was planned, using a parachute that aimed at preventing a crash landing and thus protecting the internal components. The capsule was activated and ejected as planned. Thermal measurements of the TPS were received by the capsule as it returned to Earth. This satisfied the main objective of the flight. However, the capsule did not have a successful parachute deployment, due to a timing issue. Therefore, the capsule was not able to be recovered in one piece. The thermal data measured during the descent of this capsule demonstrated the insulative properties of the TPS.},
	urldate = {2023-10-30},
	booktitle = {{AIAA} {AVIATION} 2022 {Forum}},
	publisher = {AIAA Paper 2022-3729},
	author = {Schmidt, John D. and Nichols, J. T. and Dietz, Collin J. and Askins, Page and Ford, Kirsten F. and Perry, Andrew and Smith, William T. and Martin, Alexandre},
	year = {2022},
	note = {\_eprint: https://arc.aiaa.org/doi/pdf/10.2514/6.2022-3729},
}

View Video Presentation: https://doi.org/10.2514/6.2022-3729.vidThe Kentucky Re-entry Universal Payload System (KRUPS) is a small re-entry capsule designed as a technology testbed. For its first incarnation, KRUPS has been designed to test Thermal Protection System (TPS) material and instrumentation. TPS are used to protect spacecraft, and its payload, from the extreme conditions of planetary entry. KRUPS has been developed at the University of Kentucky over the past 6 years. This specific launch aimed to produce system verification, software implementation, and launch qualifications, using an atmospheric balloon platform. The capsule released from the balloon in this experiment, was designed to transmit data using the Iridium satellite network. Recovery of the capsule was planned, using a parachute that aimed at preventing a crash landing and thus protecting the internal components. The capsule was activated and ejected as planned. Thermal measurements of the TPS were received by the capsule as it returned to Earth. This satisfied the main objective of the flight. However, the capsule did not have a successful parachute deployment, due to a timing issue. Therefore, the capsule was not able to be recovered in one piece. The thermal data measured during the descent of this capsule demonstrated the insulative properties of the TPS.

@article{nd2022,
	title = {Need for hypersonics workforce development ‘an issue of national security’},
	url = {https://hypersonics.nd.edu/news-events/news/need-for-hypersonics-workforce-development-an-issue-of-national-security/},
	journal = {Hypersonics Systems Initiative - University of Notre Dame},
	year = {2022},
}

@article{streicher2022,
	title = {High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide: {II}. {Nitrogen} dilution from 1900 to 8200 {K}},
	volume = {34},
	issn = {1070-6631},
	shorttitle = {High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide},
	url = {https://doi.org/10.1063/5.0122787},
	doi = {10.1063/5.0122787},
	abstract = {This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in nitrogen (N2) to target the NO–N2 rates relevant to high-temperature air, thereby building off the argon (Ar) experiments investigated in Part I. [J. W. Streicher et al., “High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K,” Phys. Fluids 34, 116122 (2022)] Again, two continuous-wave ultraviolet laser diagnostics were used to obtain quantum-state-specific time histories of NO in high-temperature shock-tube experiments, including absorbance (α) in the ground vibrational state of NO, translational/rotational temperature (Ttr), and number density of NO (nNO). The experiments probed mixtures of 2\% and 0.4\% NO diluted in either pure N2 (NO/N2) or an equal parts N2/Ar mixture (NO/N2/Ar). The NO/N2 experiments spanned initial post-reflected-shock conditions from 1900–7000 K and 0.05–1.14 atm, while the NO/N2/Ar experiments spanned from 1900–8200 K and 0.11–1.52 atm. This work leveraged two vibrational relaxation times from Part I (τVTNO−Ar and τVTNO−NO) and extended measurements to include the vibrational–translational and vibrational–vibrational relaxation times with N2 (τVTNO−N2 and τVVNO−N2). Similarly, this work leveraged the four rate coefficients from Part I (kdNO−Ar, kdNO−NO, kfN2O, and kzNO−O) and extended measurements to include NO dissociation with N2 (kdNO−N2). A few studies have directly inferred these rates from experiments, and the current data differ from common model values. In particular, τVTNO−N2 differs slightly from the Millikan and White correlation, τVVNO−N2 is four times slower than Taylor et al.'s inference, and kdNO−N2 is four times slower than the Park two-temperature model. The unique experimental measurements and dilution in N2 in this study significantly improve the understanding of the vibrational relaxation and decomposition of NO in high-temperature air.},
	number = {11},
	urldate = {2023-08-10},
	journal = {Physics of Fluids},
	author = {Streicher, Jesse W. and Krish, Ajay and Hanson, Ronald K.},
	month = nov,
	year = {2022},
	pages = {116123},
}

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in nitrogen (N2) to target the NO–N2 rates relevant to high-temperature air, thereby building off the argon (Ar) experiments investigated in Part I. [J. W. Streicher et al., “High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K,” Phys. Fluids 34, 116122 (2022)] Again, two continuous-wave ultraviolet laser diagnostics were used to obtain quantum-state-specific time histories of NO in high-temperature shock-tube experiments, including absorbance (α) in the ground vibrational state of NO, translational/rotational temperature (Ttr), and number density of NO (nNO). The experiments probed mixtures of 2% and 0.4% NO diluted in either pure N2 (NO/N2) or an equal parts N2/Ar mixture (NO/N2/Ar). The NO/N2 experiments spanned initial post-reflected-shock conditions from 1900–7000 K and 0.05–1.14 atm, while the NO/N2/Ar experiments spanned from 1900–8200 K and 0.11–1.52 atm. This work leveraged two vibrational relaxation times from Part I (τVTNO−Ar and τVTNO−NO) and extended measurements to include the vibrational–translational and vibrational–vibrational relaxation times with N2 (τVTNO−N2 and τVVNO−N2). Similarly, this work leveraged the four rate coefficients from Part I (kdNO−Ar, kdNO−NO, kfN2O, and kzNO−O) and extended measurements to include NO dissociation with N2 (kdNO−N2). A few studies have directly inferred these rates from experiments, and the current data differ from common model values. In particular, τVTNO−N2 differs slightly from the Millikan and White correlation, τVVNO−N2 is four times slower than Taylor et al.'s inference, and kdNO−N2 is four times slower than the Park two-temperature model. The unique experimental measurements and dilution in N2 in this study significantly improve the understanding of the vibrational relaxation and decomposition of NO in high-temperature air.

@article{bearden2022,
	title = {Calibration and performance characterization of a {Mach} 5 {Ludwieg} tube},
	volume = {93},
	issn = {0034-6748},
	url = {https://doi.org/10.1063/5.0093052},
	doi = {10.1063/5.0093052},
	abstract = {Calibration, commissioning, and design features of a new Mach 5 Ludwieg Tube wind tunnel at the University of Arizona are discussed. Mach number uniformity and free-stream noise levels are measured using a Pitot rake at a range of unit Reynolds numbers and at multiple spanwise and streamwise positions. The wind tunnel is shown to have a free-stream Mach number of 4.82 with maximum variance less than 0.8\% (and less than 0.5\% at most streamwise positions). The average free-stream acoustic noise level in the core (based on Pitot pressure) is shown to be less than 1.2\% at an intermediate Reynolds number with some regions dropping locally below 1.0\%. The core flow region is measured to be 282.4 mm (11.1 in.) in diameter at the nozzle exit.},
	number = {8},
	urldate = {2023-08-08},
	journal = {Review of Scientific Instruments},
	author = {Bearden, Kyle P. and Padilla, Victor E. and Taubert, Lutz and Craig, Stuart A.},
	month = aug,
	year = {2022},
	pages = {085104},
}

Calibration, commissioning, and design features of a new Mach 5 Ludwieg Tube wind tunnel at the University of Arizona are discussed. Mach number uniformity and free-stream noise levels are measured using a Pitot rake at a range of unit Reynolds numbers and at multiple spanwise and streamwise positions. The wind tunnel is shown to have a free-stream Mach number of 4.82 with maximum variance less than 0.8% (and less than 0.5% at most streamwise positions). The average free-stream acoustic noise level in the core (based on Pitot pressure) is shown to be less than 1.2% at an intermediate Reynolds number with some regions dropping locally below 1.0%. The core flow region is measured to be 282.4 mm (11.1 in.) in diameter at the nozzle exit.

@misc{gould2022,
	title = {Pentagon’s fuel prices rose \$3 billion amid inflationary pressures},
	url = {https://www.defensenews.com/pentagon/2022/04/27/pentagons-fuel-prices-rose-3b-amid-inflationary-pressures/},
	abstract = {Spiking fuel prices will cost the Pentagon \$3 billion more than expected, and it will have to go to Congress for more money, a senior official said in congressional testimony on Wednesday.},
	language = {en},
	urldate = {2023-06-28},
	journal = {Defense News},
	author = {Gould, Joe},
	month = apr,
	year = {2022},
	note = {Section: Congress},
}

Spiking fuel prices will cost the Pentagon $3 billion more than expected, and it will have to go to Congress for more money, a senior official said in congressional testimony on Wednesday.

@article{sawicki2022,
	title = {Influence of {Chemical} {Kinetics} {Models} on {Plasma} {Generation} in {Hypersonic} {Flight}},
	volume = {60},
	doi = {10.2514/1.J060615/ASSET/IMAGES/LARGE/FIGURE11.JPEG},
	abstract = {The accuracy and sensitivity of plasma generation predicted by several different chemical kinetics models is investigated in the context of weakly ionized hypersonic flowfields around the Radio Attenuation Measurement (RAM-C) vehicle. A computational fluid dynamics analysis is used to examine 13 independent trajectory points along the RAM-C II flight, and an assessment of the chemistry models is made by comparing results to available flight measurements. The limitations of making such comparisons with the raw flight data are established in detail, including the inherent shortcomings associated with interpolating the flight data to assess a single trajectory point. Two separate geometries are evaluated in this study, as the initial RAM-C geometry was altered during flight after its nose cap was pyrotechnically ejected. The blunter post-ejection geometry generates more electrons in the stagnation region. In general, good agreement is found between each chemistry model and flight data from both the electrostatic probe and reflectometer stations above 56 km. An expected sizable gap exists between the simulations and reflectometer data at lower altitudes. The impact of forward reaction rates, equilibrium constants, and number of species varies considerably based on altitude, velocity, and position along the body.},
	number = {1},
	journal = {AIAA Journal},
	author = {Sawicki, Pawel and Chaudhry, Ross S. and Boyd, Iain D.},
	month = aug,
	year = {2022},
	note = {Publisher: AIAA International},
	keywords = {Angle of Attack, Bow Shock, CFD Analysis, Chemical Kinetics, Flight Data, Flight Testing, Free Molecular Flow, Hypersonic Flight, No Slip Condition, Plasma Diagnostics},
	pages = {31--40},
}

The accuracy and sensitivity of plasma generation predicted by several different chemical kinetics models is investigated in the context of weakly ionized hypersonic flowfields around the Radio Attenuation Measurement (RAM-C) vehicle. A computational fluid dynamics analysis is used to examine 13 independent trajectory points along the RAM-C II flight, and an assessment of the chemistry models is made by comparing results to available flight measurements. The limitations of making such comparisons with the raw flight data are established in detail, including the inherent shortcomings associated with interpolating the flight data to assess a single trajectory point. Two separate geometries are evaluated in this study, as the initial RAM-C geometry was altered during flight after its nose cap was pyrotechnically ejected. The blunter post-ejection geometry generates more electrons in the stagnation region. In general, good agreement is found between each chemistry model and flight data from both the electrostatic probe and reflectometer stations above 56 km. An expected sizable gap exists between the simulations and reflectometer data at lower altitudes. The impact of forward reaction rates, equilibrium constants, and number of species varies considerably based on altitude, velocity, and position along the body.

@inproceedings{castillogomez2022,
	title = {Wall-{Modeled} {Large}-{Eddy} {Simulations} of {Turbulent} {Mach} 3.5, 8, and 14 {Boundary} {Layers} - {Effect} of {Mach} {Number} on {Aero}-{Optical} {Distortions}},
	doi = {10.2514/6.2022-3441},
	language = {en},
	publisher = {AIAA Paper 2022-2441},
	author = {Castillo Gomez, Pedro and Gross, Andreas and Guildenbecher, Daniel R. and Miller, Nathan E. and Lynch, Kyle P.},
	month = jun,
	year = {2022},
}

@inproceedings{castillo2022,
	title = {Wall-{Modeled} {Large}-{Eddy} {Simulations} of {Mach} 8 {Turbulent} {Boundary} {Layer} and {Computation} of {Aero}-{Optical} {Distortions}},
	isbn = {978-1-62410-631-6},
	doi = {10.2514/6.2022-1674},
	abstract = {Compressible wall modeled large-eddy simulations of a Mach eight turbulent boundary layer over a flat plate were carried out for the conditions of the Hypersonic Wind Tunnel at Sandia National Laboratories. Overall good agreement of the velocity and temperature profiles is obtained with reference data from a direct numerical simulation and a theoretical relationship. Profiles of the resolved root-mean-square velocity fluctuations are in adequate agreement with the reference data. The refractive index is calculated from the density field and integrated along an expected beam path to calculate the optical path length. Then, by subtracting a bilinear fit of the instantaneous optical path length, the optical path difference is obtained. The computed aero-optical path difference shows a similar dependence on the aperture size as in the literature. The normalized root-mean-square optical path difference from the present wall-modeled large-eddy simulations and a reference direct numerical simulation and experiment are in good agreement. The optical path distortion is slightly above the value predicted by a semi-analytical relationship from the literature. Finally, instantaneous snapshots of the flow are analyzed via proper orthogonal decomposition and the optical path distortion is computed from subsets of the modes. The optical path distortion converges quickly with increasing number of modes which suggests that the main contribution comes from large energetic flow structures.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Castillo, Pedro and Gross, Andreas and Miller, Nathan E. and Guildenbecher, Daniel R. and Lynch, Kyle P.},
	year = {2022},
}

Compressible wall modeled large-eddy simulations of a Mach eight turbulent boundary layer over a flat plate were carried out for the conditions of the Hypersonic Wind Tunnel at Sandia National Laboratories. Overall good agreement of the velocity and temperature profiles is obtained with reference data from a direct numerical simulation and a theoretical relationship. Profiles of the resolved root-mean-square velocity fluctuations are in adequate agreement with the reference data. The refractive index is calculated from the density field and integrated along an expected beam path to calculate the optical path length. Then, by subtracting a bilinear fit of the instantaneous optical path length, the optical path difference is obtained. The computed aero-optical path difference shows a similar dependence on the aperture size as in the literature. The normalized root-mean-square optical path difference from the present wall-modeled large-eddy simulations and a reference direct numerical simulation and experiment are in good agreement. The optical path distortion is slightly above the value predicted by a semi-analytical relationship from the literature. Finally, instantaneous snapshots of the flow are analyzed via proper orthogonal decomposition and the optical path distortion is computed from subsets of the modes. The optical path distortion converges quickly with increasing number of modes which suggests that the main contribution comes from large energetic flow structures.

@article{huang2022,
	title = {Study of fluid–thermal–structural interaction in high-temperature high-speed flow using multi-fidelity multi-variate surrogates},
	volume = {113},
	doi = {10.1016/j.jfluidstructs.2022.103682},
	abstract = {This study investigates the impact of the high-temperature effect, especially the real gas effect and chemical reactions, on hypersonic aerothermodynamic solutions of double cone and double wedge configurations, as well as the fluid–thermal–structural interaction of a double wedge configuration in hypersonic flow. First, a high-temperature computational fluid dynamics (CFD) code was benchmarked and correlated with experimental results, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, the multi-fidelity multi-variate Gaussian process regression (M2GPR ) method for problems with high-dimensional outputs was developed to create an aerothermal surrogate model. The model achieves a balance between model accuracy and computational cost of sample generation, using the combination of a few high-fidelity samples and many low-fidelity samples. The numerical examples show that, using the M2GPR formulation, the required number of high-fidelity samples may be reduced by over 80\% while maintaining an accuracy comparable to the high-fidelity CFD solvers. In addition, a geodesic-distance-based metric is developed to inform the choice of high-dimensional datasets of different fidelities for the M2GPR surrogate with improved accuracy. Finally, the aerothermal surrogate was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, emphasizing the necessity of the accurate characterization of the localized heat flux for reasonable assessment of the response of a compliant structure in high-speed high-temperature flowfield.},
	journal = {Journal of Fluids and Structures},
	author = {Huang, Daning and Sadagopan, Aravinth and Düzel, Ümran and Hanquist, Kyle M.},
	year = {2022},
	keywords = {Grassmannian geodesic distance, High-speed fluid–thermal–structural interaction, High-temperature effects, Hypersonic aerothermodynamics, Multi-fidelity surrogate modeling, Multivariate Gaussian process regression, graduate\_student, own},
}

This study investigates the impact of the high-temperature effect, especially the real gas effect and chemical reactions, on hypersonic aerothermodynamic solutions of double cone and double wedge configurations, as well as the fluid–thermal–structural interaction of a double wedge configuration in hypersonic flow. First, a high-temperature computational fluid dynamics (CFD) code was benchmarked and correlated with experimental results, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, the multi-fidelity multi-variate Gaussian process regression (M2GPR ) method for problems with high-dimensional outputs was developed to create an aerothermal surrogate model. The model achieves a balance between model accuracy and computational cost of sample generation, using the combination of a few high-fidelity samples and many low-fidelity samples. The numerical examples show that, using the M2GPR formulation, the required number of high-fidelity samples may be reduced by over 80% while maintaining an accuracy comparable to the high-fidelity CFD solvers. In addition, a geodesic-distance-based metric is developed to inform the choice of high-dimensional datasets of different fidelities for the M2GPR surrogate with improved accuracy. Finally, the aerothermal surrogate was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, emphasizing the necessity of the accurate characterization of the localized heat flux for reasonable assessment of the response of a compliant structure in high-speed high-temperature flowfield.

@misc{durston2022,
	address = {Oshkosh, WI},
	title = {{NASA} {Supersonics} {Research} - {Leading} {Toward} {Quiet} {Supersonic} {Flight}!!},
	author = {Durston, Don},
	year = {2022},
}

@article{qiu2022,
	title = {Multiscale {Modeling} of {Gas}–{Solid} {Surface} {Interactions} {Under} {High}-{Temperature} {Gas} {Effect}},
	doi = {10.2514/1.T6456},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Qiu, Tianhao and Zhao, Mingcan and Li, Yanping and Li, Chengxiang and Ge, Wei},
	month = jun,
	year = {2022},
	pages = {1--13},
}

@article{gimelshein2022,
	title = {Kinetic and {Continuum} {Modeling} of {High}-{Temperature} {Air} {Relaxation}},
	doi = {10.2514/1.T6462},
	abstract = {Fully kinetic, vibrationally kinetic, and continuum solvers with varying model fidelity are used in this work to model the high-temperature relaxation of air in 7230 and 15,000 K adiabatic heat bat...},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Gimelshein, Sergey F. and Wysong, Ingrid J. and Fangman, Alexander J. and Andrienko, Daniil A. and Kunova, Olga V. and Kustova, Elena V. and Morgado, Fabio and Garbacz, Catarina and Fossati, Marco and Hanquist, Kyle M.},
	year = {2022},
	keywords = {CFD, Chemical Equilibrium, Direct Simulation Monte Carlo, Heat Flux, High Enthalpy Shock Tunnel, Hypersonic Flows, Nonequilibrium Thermochemistry, Nonequilibrium Vibrational Chemical Kinetics, Stagnation Point, Vibrational Energy, own},
	pages = {1--23},
}

Fully kinetic, vibrationally kinetic, and continuum solvers with varying model fidelity are used in this work to model the high-temperature relaxation of air in 7230 and 15,000 K adiabatic heat bat...

@article{gimelshein2022c,
	title = {Kinetic and {Continuum} {Modeling} of {High}-{Temperature} {Oxygen} and {Nitrogen} {Binary} {Mixtures}},
	doi = {10.2514/1.T6258},
	abstract = {The present paper provides a comprehensive comparative analysis of thermochemistry models of various fidelity levels developed in leading research groups around the world. Fully kinetic, hybrid kin...},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Gimelshein, Sergey F. and Wysong, Ingrid J. and Fangman, Alexander J. and Andrienko, Daniil A. and Kunova, Olga V. and Kustova, Elena V. and Garbacz, Catarina and Fossati, Marco and Hanquist, Kyle M.},
	year = {2022},
	keywords = {own},
	pages = {1--20},
}

The present paper provides a comprehensive comparative analysis of thermochemistry models of various fidelity levels developed in leading research groups around the world. Fully kinetic, hybrid kin...

@misc{tumuklu2022b,
	address = {32nd International Symposium on Rarefied Gas Dynamics},
	type = {Conference {Presentation}},
	title = {Hypersonic {Turbulence} {Modeling} from {Rarefied} to {Continuum} {Regimes}},
	author = {Tumuklu, Ozgur and Hanquist, Kyle M.},
	year = {2022},
	keywords = {own, presentation},
}

@article{morgado2022,
	title = {Impact of {Anisotropic} {Mesh} {Adaptation} on the {Aerothermodynamics} of {Atmospheric} {Reentry}},
	volume = {60},
	issn = {0001-1452, 1533-385X},
	doi = {10.2514/1.J061071},
	language = {en},
	number = {7},
	urldate = {2023-01-12},
	journal = {AIAA Journal},
	author = {Morgado, Fábio and Garbacz, Catarina and Fossati, Marco},
	month = jul,
	year = {2022},
	pages = {3973--3989},
}

@techreport{vasile2022,
	title = {High-speed {Army} {Reference} {Vehicle}},
	language = {en},
	number = {ARL-TN-1128},
	institution = {Army Research Laboratory},
	author = {Vasile, Joseph D and Fresconi, Frank and DeSpirito, James and Duca, Marco and Recchia, Thomas and Grantham, Brian and Bowersox, Rodney D W and White, Edward B},
	year = {2022},
}

@article{chazot2022,
	title = {Hypersonic {Challenges}},
	url = {https://www.aiaa.org/events-learning/event/2022/04/28/default-calendar/aiaa-webinar-hypersonics-challenges},
	author = {Chazot, O.},
	year = {2022},
	note = {Publisher: AIAA},
}

@inproceedings{tumuklu2022c,
	title = {Development and {Validation} {Studies} of a {Multi}-purpose {DSMC} {Code}},
	isbn = {978-1-62410-631-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2022-2017},
	doi = {10.2514/6.2022-2017},
	abstract = {A parallel direct simulation Monte Carlo (DSMC) solver has been developed to ultimately couple with an existing granular code1–3 in order to model positioning-rocket plume expansion in the lunar atmosphere and its interaction with the regolith. The challenge is to develop of a multi-species DSMC efficient model and code to fit the target problem. This model and code are here described and results from the model are compared for validation and verification purposes either with existing experimental data or with similar results from similar simulations of wall-bounded canonical flows. In particular, the modeling of Couette flow with different collision schemes provides an opportunity to select a sufficiently numerically efficient collision model to reduce computational costs. Since the objective of the code is to study expansion flows including the plume species of CO2, N2, and H2 O and their interactions with the multi-species composition of the Moon atmosphere (i.e. Ar, He, and Ne), thermal and mass diffusion of mixtures were also studied to show that the code accurately models multispecies situations. To acquire such an ability, the collision and sampling algorithm of the single species code was improved to handle complex multi-species gas interactions. A good agreement with experimental data is achieved, showing that the code accurately predicts the thermal and mass diffusion coefficients of mixtures. Finally, the expanding nature of the plume results in thermochemical nonequilibrium flow, especially in rarefied environments, due to insufficient collision rates. To this end, the rate and the amount of energy transfer among the translational, rotational, and vibrational modes are tested with the previous numerical data and with analytical results.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Tumuklu, Ozgur and Bellan, Josette},
	year = {2022},
}

A parallel direct simulation Monte Carlo (DSMC) solver has been developed to ultimately couple with an existing granular code1–3 in order to model positioning-rocket plume expansion in the lunar atmosphere and its interaction with the regolith. The challenge is to develop of a multi-species DSMC efficient model and code to fit the target problem. This model and code are here described and results from the model are compared for validation and verification purposes either with existing experimental data or with similar results from similar simulations of wall-bounded canonical flows. In particular, the modeling of Couette flow with different collision schemes provides an opportunity to select a sufficiently numerically efficient collision model to reduce computational costs. Since the objective of the code is to study expansion flows including the plume species of CO2, N2, and H2 O and their interactions with the multi-species composition of the Moon atmosphere (i.e. Ar, He, and Ne), thermal and mass diffusion of mixtures were also studied to show that the code accurately models multispecies situations. To acquire such an ability, the collision and sampling algorithm of the single species code was improved to handle complex multi-species gas interactions. A good agreement with experimental data is achieved, showing that the code accurately predicts the thermal and mass diffusion coefficients of mixtures. Finally, the expanding nature of the plume results in thermochemical nonequilibrium flow, especially in rarefied environments, due to insufficient collision rates. To this end, the rate and the amount of energy transfer among the translational, rotational, and vibrational modes are tested with the previous numerical data and with analytical results.

@inproceedings{tumuklu2022,
	title = {Development and {Validation} {Studies} of a {Multi}-purpose {DSMC} {Code}},
	isbn = {978-1-62410-631-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2022-2017},
	doi = {10.2514/6.2022-2017},
	abstract = {A parallel direct simulation Monte Carlo (DSMC) solver has been developed to ultimately couple with an existing granular code1–3 in order to model positioning-rocket plume expansion in the lunar atmosphere and its interaction with the regolith. The challenge is to develop of a multi-species DSMC efficient model and code to fit the target problem. This model and code are here described and results from the model are compared for validation and verification purposes either with existing experimental data or with similar results from similar simulations of wall-bounded canonical flows. In particular, the modeling of Couette flow with different collision schemes provides an opportunity to select a sufficiently numerically efficient collision model to reduce computational costs. Since the objective of the code is to study expansion flows including the plume species of CO2, N2, and H2 O and their interactions with the multi-species composition of the Moon atmosphere (i.e. Ar, He, and Ne), thermal and mass diffusion of mixtures were also studied to show that the code accurately models multispecies situations. To acquire such an ability, the collision and sampling algorithm of the single species code was improved to handle complex multi-species gas interactions. A good agreement with experimental data is achieved, showing that the code accurately predicts the thermal and mass diffusion coefficients of mixtures. Finally, the expanding nature of the plume results in thermochemical nonequilibrium flow, especially in rarefied environments, due to insufficient collision rates. To this end, the rate and the amount of energy transfer among the translational, rotational, and vibrational modes are tested with the previous numerical data and with analytical results.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Tumuklu, Ozgur and Bellan, Josette},
	year = {2022},
}

A parallel direct simulation Monte Carlo (DSMC) solver has been developed to ultimately couple with an existing granular code1–3 in order to model positioning-rocket plume expansion in the lunar atmosphere and its interaction with the regolith. The challenge is to develop of a multi-species DSMC efficient model and code to fit the target problem. This model and code are here described and results from the model are compared for validation and verification purposes either with existing experimental data or with similar results from similar simulations of wall-bounded canonical flows. In particular, the modeling of Couette flow with different collision schemes provides an opportunity to select a sufficiently numerically efficient collision model to reduce computational costs. Since the objective of the code is to study expansion flows including the plume species of CO2, N2, and H2 O and their interactions with the multi-species composition of the Moon atmosphere (i.e. Ar, He, and Ne), thermal and mass diffusion of mixtures were also studied to show that the code accurately models multispecies situations. To acquire such an ability, the collision and sampling algorithm of the single species code was improved to handle complex multi-species gas interactions. A good agreement with experimental data is achieved, showing that the code accurately predicts the thermal and mass diffusion coefficients of mixtures. Finally, the expanding nature of the plume results in thermochemical nonequilibrium flow, especially in rarefied environments, due to insufficient collision rates. To this end, the rate and the amount of energy transfer among the translational, rotational, and vibrational modes are tested with the previous numerical data and with analytical results.

@article{viladegut2022,
	title = {Catalytic characterization in plasma wind tunnels under the influence of gaseous recombination},
	volume = {34},
	doi = {10.1063/5.0077603},
	abstract = {The catalytic properties of materials used in re-usable thermal protection systems (TPSs) of re-entry vehicles are mainly characterized in plasma wind tunnels. These facilities are adequate to repr...},
	number = {2},
	journal = {Physics of Fluids},
	author = {Viladegut, A. and Chazot, O.},
	month = feb,
	year = {2022},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	pages = {027108--027108},
}

The catalytic properties of materials used in re-usable thermal protection systems (TPSs) of re-entry vehicles are mainly characterized in plasma wind tunnels. These facilities are adequate to repr...

@inproceedings{mckown2022,
	title = {Attitude {Reconstruction} of {Free}-{Flight} {CFD} {Generated} {Trajectories} {Using} {Non}-{Linear} {Pitch} {Damping} {Coefficient} {Curv}},
	isbn = {978-1-62410-631-6},
	url = {https://arc.aiaa.org/doi/10.2514/6.2022-1169},
	doi = {10.2514/6.2022-1169},
	abstract = {Attitude history reconstruction of Free-flight CFD generated trajectories with non-linear pitch damping coefficient curves is investigated. Free-flight CFD simulations of the capsule shape used for the Genesis sample return mission and the upcoming Dragonfly mission to Titan are conducted for 1-, 2-, and 3-degree-of-freedom cases. Two different data reduction methodologies are employed to derive a pitch damping curve as a function of instantaneous angle of attack. These curves are then used to reconstruct the attitude history of the body which is compared to the raw simulation results. While both data reduction methods produce pitch damping curves that can generally reconstruct the motion seen in the Free-flight simulations, it is found that optimization of the pitch damping curve using an inverse estimation process yields superior and more generalizable results. Further refinement of this technique could allow pitch damping curves derived using CFD to serve as a capability complementary to existing techniques for dynamic stability characterization.},
	publisher = {AIAA Paper 2022-1169},
	author = {McKown, Quincy E. and Kazemba, Cole D. and Stern, Eric C. and Brock, Joseph M.},
	year = {2022},
}

Attitude history reconstruction of Free-flight CFD generated trajectories with non-linear pitch damping coefficient curves is investigated. Free-flight CFD simulations of the capsule shape used for the Genesis sample return mission and the upcoming Dragonfly mission to Titan are conducted for 1-, 2-, and 3-degree-of-freedom cases. Two different data reduction methodologies are employed to derive a pitch damping curve as a function of instantaneous angle of attack. These curves are then used to reconstruct the attitude history of the body which is compared to the raw simulation results. While both data reduction methods produce pitch damping curves that can generally reconstruct the motion seen in the Free-flight simulations, it is found that optimization of the pitch damping curve using an inverse estimation process yields superior and more generalizable results. Further refinement of this technique could allow pitch damping curves derived using CFD to serve as a capability complementary to existing techniques for dynamic stability characterization.

@article{lynch2022,
	title = {Aero-{Optical} {Measurements} of a {Mach} 8 {Boundary} {Layer}},
	issn = {0001-1452},
	doi = {10.2514/1.J062363},
	abstract = {Measurements are presented of the aero-optic distortion produced by a Mach 8 turbulent boundary layer in the Sandia Hypersonic Wind Tunnel. Flat optical windows installed in conformal test section walls enabled a double-pass arrangement of a collimated laser beam. The distortion of this beam was imaged by a high-speed Shack–Hartmann sensor using variable aperture sizes at a sampling rate of up to 1.75 MHz. Analysis is performed using two processing methods to extract the aero-optic distortion from the data: 1) a stitching method is applied to extract wavefronts without bias from a limited aperture size, and 2) a novel de-aliasing algorithm is proposed to extract convective-only deflection angle spectra and is demonstrated to correctly quantify the physical spectra even for relatively low sampling rates. Measurements of speed and size of large-scale convecting aero-optical structures are also presented. Overall levels of aero-optic distortions were estimated, and the results are compared with an existing theoretical model. It is shown that this model underpredicts the measured distortions regardless of the processing method used. Possible explanations for this discrepancy are presented. Finally, levels of the global streamwise jitter were estimated for different aperture sizes and compared with the results for the subsonic boundary layer. The results represent to-date the highest Mach number for which aero-optic boundary-layer distortion measurements are available.},
	urldate = {2023-02-22},
	journal = {AIAA Journal},
	author = {Lynch, Kyle P. and Miller, Nathan E. and Guildenbecher, Daniel R. and Butler, Luke and Gordeyev, Stanislav},
	year = {2022},
	pages = {1--11},
}

Measurements are presented of the aero-optic distortion produced by a Mach 8 turbulent boundary layer in the Sandia Hypersonic Wind Tunnel. Flat optical windows installed in conformal test section walls enabled a double-pass arrangement of a collimated laser beam. The distortion of this beam was imaged by a high-speed Shack–Hartmann sensor using variable aperture sizes at a sampling rate of up to 1.75 MHz. Analysis is performed using two processing methods to extract the aero-optic distortion from the data: 1) a stitching method is applied to extract wavefronts without bias from a limited aperture size, and 2) a novel de-aliasing algorithm is proposed to extract convective-only deflection angle spectra and is demonstrated to correctly quantify the physical spectra even for relatively low sampling rates. Measurements of speed and size of large-scale convecting aero-optical structures are also presented. Overall levels of aero-optic distortions were estimated, and the results are compared with an existing theoretical model. It is shown that this model underpredicts the measured distortions regardless of the processing method used. Possible explanations for this discrepancy are presented. Finally, levels of the global streamwise jitter were estimated for different aperture sizes and compared with the results for the subsonic boundary layer. The results represent to-date the highest Mach number for which aero-optic boundary-layer distortion measurements are available.

@misc{tumuklu2022a,
	address = {32nd International Symposium on Rarefied Gas Dynamics},
	title = {A hybrid {DSMC}-continuum formulation for jet expansion into rarefied flows},
	author = {Tumuklu, Ozgur and Bellan, Josette R. and Hanquist, Kyle M.},
	year = {2022},
	keywords = {own, presentation},
}

@article{yu_cfd_2021,
	title = {{CFD} {Simulation} {Strategy} for {Hypersonic} {Aerodynamic} {Heating} around a {Blunt} {Biconic}},
	volume = {2021},
	copyright = {https://creativecommons.org/licenses/by/4.0/},
	issn = {1687-5974, 1687-5966},
	url = {https://www.hindawi.com/journals/ijae/2021/8885074/},
	doi = {10.1155/2021/8885074},
	abstract = {The design of the thermal protection system requires high-precision and high-reliability CFD simulation for validation. To accurately predict the hypersonic aerodynamic heating, an overall simulation strategy based on mutual selection is proposed. Foremost, the grid criterion based on the wall cell Reynolds number is developed. Subsequently, the dependence of the turbulence model and the discretization scheme is considered. It is suggested that the appropriate value of wall cell Reynolds number is 1 through careful comparison between one another and with the available experimental data. The excessive number of cells is not recommended due to time-consuming computation. It can be seen from the results that the combination of the AUSM+ discretization scheme and the Spalart-Allmaras turbulence model has the highest accuracy. In this work, the heat flux error of the stagnation point is within 1\%, and the overall average relative error is within 10\%.},
	urldate = {2025-03-04},
	journal = {International Journal of Aerospace Engineering},
	author = {Yu, Shutian and Ni, Xinyue and Chen, Fansheng},
	editor = {Xie, Kan},
	month = apr,
	year = {2021},
	pages = {1--11},
}

The design of the thermal protection system requires high-precision and high-reliability CFD simulation for validation. To accurately predict the hypersonic aerodynamic heating, an overall simulation strategy based on mutual selection is proposed. Foremost, the grid criterion based on the wall cell Reynolds number is developed. Subsequently, the dependence of the turbulence model and the discretization scheme is considered. It is suggested that the appropriate value of wall cell Reynolds number is 1 through careful comparison between one another and with the available experimental data. The excessive number of cells is not recommended due to time-consuming computation. It can be seen from the results that the combination of the AUSM+ discretization scheme and the Spalart-Allmaras turbulence model has the highest accuracy. In this work, the heat flux error of the stagnation point is within 1%, and the overall average relative error is within 10%.

@misc{slater2021,
	title = {Uncertainty and {Error} in {CFD} {Simulations}},
	url = {https://www.grc.nasa.gov/WWW/wind/valid/tutorial/errors.html},
	journal = {NPARC Alliance CFD Verification and Validation Web Site},
	author = {Slater, John},
	month = feb,
	year = {2021},
}

@article{li2021,
	title = {Numerical {Investigation} of {Inlet} {Thermodynamic} {Conditions} on {Solid} {Fuel} {Ramjet} {Performances}},
	volume = {2021},
	doi = {10.1155/2021/8868288},
	abstract = {In this work, 2D numerical RANS (Reynolds Average Navier-Stokes) simulations were carried out to investigate the thermodynamic performance of a solid fuel ramjet (SFRJ) with different inlet conditions. This is achieved by using an in-house FORTRAN code to simulate a 2D turbulent, reacting, unsteady flow in the ramjet engine. The inlet conditions are characterized by three key parameters: (1) swirl number (), (2) mass flow rate (), and (3) inlet temperature (). With the code numerically validated by benchmarking with a number of computed cases, it is applied to perform systematic studies on the turbulent flow recirculation, combustion, and heat transfer characteristics. It is found that increasing , , or can dramatically enhance the combustion heat release rate, regression rate, and combustor average temperature. Furthermore, the analysis on the chemical reaction intermediate (CO) reveals that the chemical reaction is more sufficient with increased , but . In addition, a secondary vortex is generated at the corner of the backward facing step in the presence of a swirl flow resulting from the instability of the shear layer. Finally, the nonlinear correlations between the heat transfer, combustion characteristics, and flow field characteristics and the corresponding inlet thermodynamic parameters are identified.},
	language = {en},
	urldate = {2024-05-29},
	journal = {International Journal of Aerospace Engineering},
	author = {Li, Weixuan and Zhao, Dan and Chen, Xiong and Zhu, Liang and Ni, Siliang},
	month = jan,
	year = {2021},
}

In this work, 2D numerical RANS (Reynolds Average Navier-Stokes) simulations were carried out to investigate the thermodynamic performance of a solid fuel ramjet (SFRJ) with different inlet conditions. This is achieved by using an in-house FORTRAN code to simulate a 2D turbulent, reacting, unsteady flow in the ramjet engine. The inlet conditions are characterized by three key parameters: (1) swirl number (), (2) mass flow rate (), and (3) inlet temperature (). With the code numerically validated by benchmarking with a number of computed cases, it is applied to perform systematic studies on the turbulent flow recirculation, combustion, and heat transfer characteristics. It is found that increasing , , or can dramatically enhance the combustion heat release rate, regression rate, and combustor average temperature. Furthermore, the analysis on the chemical reaction intermediate (CO) reveals that the chemical reaction is more sufficient with increased , but . In addition, a secondary vortex is generated at the corner of the backward facing step in the presence of a swirl flow resulting from the instability of the shear layer. Finally, the nonlinear correlations between the heat transfer, combustion characteristics, and flow field characteristics and the corresponding inlet thermodynamic parameters are identified.

@misc{slater2021,
	title = {Uncertainty and {Error} in {CFD} {Simulations}},
	url = {https://www.grc.nasa.gov/WWW/wind/valid/tutorial/errors.html},
	journal = {NPARC Alliance CFD Verification and Validation Web Site},
	author = {Slater, John},
	month = feb,
	year = {2021},
}

@inproceedings{andrienko2021,
	title = {Computational fluid dynamic model of electron transpiration cooling in weakly ionized air flows},
	abstract = {View Video Presentation: https://doi.org/10.2514/6.2021-0684.vidThe present paper is concerned with the computational fluid dynamic model of a cesium-wetted tungsten surface and associated thermionic emission under hypersonic flight conditions. A set of Navier-Stokes equations coupled with the finite-rate cesium-air plasma model and Ohm's law is used to model a two-dimensional viscous, thermally conductive, and thermochemically reactive hypersonic flow. Electron emission is modeled via the Richardson-Dushman equation for saturation current. Additionally, a one-dimensional full fluid moment model of plasma sheath is used to identify the onset of space charge limited emission in the presence of NO+ and Cs+ ions. The computer model, while being actively developed, is aimed to describe a closed-loop operation of an electron transpiration cooling concept of a metallic surface of a leading edge in two-dimensional geometry. A notional geometry of a 1 cm radius of curvature leading edge at Mach 14 and 60 km of altitude with assumed ideal thermionic electron emission for wall temperature of 1500K indicates that significant electron and cesium evaporation cooling is expected, and the emission may not reach the space-charge limit with sufficient amount of ions in the flow.},
	urldate = {2024-04-30},
	booktitle = {{AIAA} {Scitech} 2021 {Forum}},
	publisher = {AIAA Paper 2021-0684},
	author = {Andrienko, Daniil and Sahu, Rupali and Tropina, Albina and Miles, Richard B. and Hara, Kentaro},
	year = {2021},
}

View Video Presentation: https://doi.org/10.2514/6.2021-0684.vidThe present paper is concerned with the computational fluid dynamic model of a cesium-wetted tungsten surface and associated thermionic emission under hypersonic flight conditions. A set of Navier-Stokes equations coupled with the finite-rate cesium-air plasma model and Ohm's law is used to model a two-dimensional viscous, thermally conductive, and thermochemically reactive hypersonic flow. Electron emission is modeled via the Richardson-Dushman equation for saturation current. Additionally, a one-dimensional full fluid moment model of plasma sheath is used to identify the onset of space charge limited emission in the presence of NO+ and Cs+ ions. The computer model, while being actively developed, is aimed to describe a closed-loop operation of an electron transpiration cooling concept of a metallic surface of a leading edge in two-dimensional geometry. A notional geometry of a 1 cm radius of curvature leading edge at Mach 14 and 60 km of altitude with assumed ideal thermionic electron emission for wall temperature of 1500K indicates that significant electron and cesium evaporation cooling is expected, and the emission may not reach the space-charge limit with sufficient amount of ions in the flow.

@article{lu2021,
	title = {{DeepXDE}: {A} {Deep} {Learning} {Library} for {Solving} {Differential} {Equations}},
	volume = {63},
	issn = {0036-1445},
	shorttitle = {{DeepXDE}},
	doi = {10.1137/19M1274067},
	abstract = {Uncertainty quantification (UQ) in machine learning is currently drawing increasing research interest, driven by the rapid deployment of deep neural networks across different fields, such as computer vision and natural language processing, and by the need for reliable tools in risk-sensitive applications. Recently, various machine learning models have also been developed to tackle problems in the field of scientific computing with applications to computational science and engineering (CSE). Physics-informed neural networks and deep operator networks are two such models for solving partial differential equations (PDEs) and learning operator mappings, respectively. In this regard, a comprehensive study of UQ methods tailored specifically for scientific machine learning (SciML) models has been provided in [A. F. Psaros et al., J. Comput. Phys., 477 (2023), art. 111902]. Nevertheless, and despite their theoretical merit, implementations of these methods are not straightforward, especially in large-scale CSE applications, hindering their broad adoption in both research and industry settings. In this paper, we present an open-source Python library (ŭlhttps://github.com/Crunch-UQ4MI), termed NeuralUQ and accompanied by an educational tutorial, for employing UQ methods for SciML in a convenient and structured manner. The library, designed for both educational and research purposes, supports multiple modern UQ methods and SciML models. It is based on a succinct workflow and facilitates flexible employment and easy extensions by the users. We first present a tutorial of NeuralUQ and subsequently demonstrate its applicability and efficiency in four diverse examples, involving dynamical systems and high-dimensional parametric and time-dependent PDEs.},
	number = {1},
	urldate = {2024-04-24},
	journal = {SIAM Review},
	author = {Lu, Lu and Meng, Xuhui and Mao, Zhiping and Karniadakis, George Em},
	month = jan,
	year = {2021},
	pages = {208--228},
}

Uncertainty quantification (UQ) in machine learning is currently drawing increasing research interest, driven by the rapid deployment of deep neural networks across different fields, such as computer vision and natural language processing, and by the need for reliable tools in risk-sensitive applications. Recently, various machine learning models have also been developed to tackle problems in the field of scientific computing with applications to computational science and engineering (CSE). Physics-informed neural networks and deep operator networks are two such models for solving partial differential equations (PDEs) and learning operator mappings, respectively. In this regard, a comprehensive study of UQ methods tailored specifically for scientific machine learning (SciML) models has been provided in [A. F. Psaros et al., J. Comput. Phys., 477 (2023), art. 111902]. Nevertheless, and despite their theoretical merit, implementations of these methods are not straightforward, especially in large-scale CSE applications, hindering their broad adoption in both research and industry settings. In this paper, we present an open-source Python library (ŭlhttps://github.com/Crunch-UQ4MI), termed NeuralUQ and accompanied by an educational tutorial, for employing UQ methods for SciML in a convenient and structured manner. The library, designed for both educational and research purposes, supports multiple modern UQ methods and SciML models. It is based on a succinct workflow and facilitates flexible employment and easy extensions by the users. We first present a tutorial of NeuralUQ and subsequently demonstrate its applicability and efficiency in four diverse examples, involving dynamical systems and high-dimensional parametric and time-dependent PDEs.

@article{schiassi2021,
	title = {Extreme theory of functional connections: {A} fast physics-informed neural network method for solving ordinary and partial differential equations},
	volume = {457},
	issn = {0925-2312},
	shorttitle = {Extreme theory of functional connections},
	doi = {10.1016/j.neucom.2021.06.015},
	abstract = {We present a novel, accurate, fast, and robust physics-informed neural network method for solving problems involving differential equations (DEs), called Extreme Theory of Functional Connections, or X-TFC. The proposed method is a synergy of two recently developed frameworks for solving problems involving DEs: the Theory of Functional Connections TFC, and the Physics-Informed Neural Networks PINN. Here, the latent solution of the DEs is approximated by a TFC constrained expression that employs a Neural Network (NN) as the free-function. The TFC approximated solution form always analytically satisfies the constraints of the DE, while maintaining a NN with unconstrained parameters. X-TFC uses a single-layer NN trained via the Extreme Learning Machine (ELM) algorithm. This choice is based on the approximating properties of the ELM algorithm that reduces the training of the network to a simple least-squares, because the only trainable parameters are the output weights. The proposed methodology was tested over a wide range of problems including the approximation of solutions to linear and nonlinear ordinary DEs (ODEs), systems of ODEs, and partial DEs (PDEs). The results show that, for most of the problems considered, X-TFC achieves high accuracy with low computational time, even for large scale PDEs, without suffering the curse of dimensionality.},
	urldate = {2024-04-24},
	journal = {Neurocomputing},
	author = {Schiassi, Enrico and Furfaro, Roberto and Leake, Carl and De Florio, Mario and Johnston, Hunter and Mortari, Daniele},
	month = oct,
	year = {2021},
	keywords = {Extreme learning machine, Functional interpolation, Least-squares, Numerical methods, Physics-informed neural networks, Universal approximator},
	pages = {334--356},
}

We present a novel, accurate, fast, and robust physics-informed neural network method for solving problems involving differential equations (DEs), called Extreme Theory of Functional Connections, or X-TFC. The proposed method is a synergy of two recently developed frameworks for solving problems involving DEs: the Theory of Functional Connections TFC, and the Physics-Informed Neural Networks PINN. Here, the latent solution of the DEs is approximated by a TFC constrained expression that employs a Neural Network (NN) as the free-function. The TFC approximated solution form always analytically satisfies the constraints of the DE, while maintaining a NN with unconstrained parameters. X-TFC uses a single-layer NN trained via the Extreme Learning Machine (ELM) algorithm. This choice is based on the approximating properties of the ELM algorithm that reduces the training of the network to a simple least-squares, because the only trainable parameters are the output weights. The proposed methodology was tested over a wide range of problems including the approximation of solutions to linear and nonlinear ordinary DEs (ODEs), systems of ODEs, and partial DEs (PDEs). The results show that, for most of the problems considered, X-TFC achieves high accuracy with low computational time, even for large scale PDEs, without suffering the curse of dimensionality.

@misc{liza2021,
	address = {74th Annual Meeting of the Division of Fluid Dynamics, American Physical Society},
	type = {Conference {Presentation}},
	title = {Examining turbulent length scales and flow correlations in a direct numerical simulation study of a hypersonic boundary layer flow produced by a uniform aspect ratio mesh using a high-resolution low dissipation massively parallel {CFD} code.},
	author = {Liza, Martin E. and Burton, Gregory and Hanquist, Kyle M.},
	year = {2021},
	keywords = {own, presentation},
}

@article{aguirre2021,
	title = {Processing and microstructure of {ZrB2}–{SiC} composite prepared by reactive spark plasma sintering},
	volume = {11},
	issn = {2590-048X},
	doi = {10.1016/j.rinma.2021.100217},
	abstract = {In-situ formation of ZrB2–SiC composites was investigated by reactive spark plasma sintering of precursor powders according to the reaction B4C + 2ZrC + 3Si → 3SiC + 2ZrB2. The reaction and process presented here involves a diffusion reaction between B4C and ZrC which facilitates the formation of ZrB2, while liquid phase sintering of silicon facilitates atomic diffusion and combines with free C from the B4C and ZrC reaction to form SiC within minutes of heating and there were some residual unreacted precursor materials. An interpenetrating matrix of ZrB2–SiC was formed that shows increased fracture toughness (6.03 ± 0.45 MPa m1/2) despite relatively low density (95 \%).},
	urldate = {2024-04-24},
	journal = {Results in Materials},
	author = {Aguirre, Trevor G. and Cramer, Corson L. and Cakmak, Ercan and Lance, Michael J. and Lowden, Richard A.},
	month = sep,
	year = {2021},
	pages = {100217},
}

In-situ formation of ZrB2–SiC composites was investigated by reactive spark plasma sintering of precursor powders according to the reaction B4C + 2ZrC + 3Si → 3SiC + 2ZrB2. The reaction and process presented here involves a diffusion reaction between B4C and ZrC which facilitates the formation of ZrB2, while liquid phase sintering of silicon facilitates atomic diffusion and combines with free C from the B4C and ZrC reaction to form SiC within minutes of heating and there were some residual unreacted precursor materials. An interpenetrating matrix of ZrB2–SiC was formed that shows increased fracture toughness (6.03 ± 0.45 MPa m1/2) despite relatively low density (95 %).

@article{johnson2021,
	title = {Effects of emitting surfaces and trapped ions on the sheath physics and current flow in multidimensional plasma systems},
	volume = {30},
	issn = {0963-0252},
	doi = {10.1088/1361-6595/abcc7b},
	abstract = {Recent one-dimensional simulations of planar sheaths with strong electron emission have shown that trapping of charge-exchange ions causes transitions from space-charge limited (SCL) to inverse sheaths. However, multidimensional emitting sheath phenomena with collisions remained unexplored, due in part to high computational cost. We developed a novel continuum kinetic code to study the sheath physics, current flow and potential distributions in two-dimensional unmagnetized configurations with emitting surfaces. For small negatively biased thermionic cathodes in a plasma, the cathode sheath can exist in an equilibrium SCL state. The SCL sheath carries an immense density of trapped ions, neutralized by thermoelectrons, within the potential well of the virtual cathode. For further increases of emitted flux, the trapped ion cloud expands in space. The trapped ion space charge causes an increase of thermionic current far beyond the saturation limit predicted by conventional collisionless SCL sheath models without ion trapping. For sufficiently strong emission, the trapped ion cloud consumes the entire 2D plasma domain, forming a mode with globally confined ions and an inverse sheath at the cathode. In situations where the emitted flux is fixed and the bias is swept (e.g. emissive probe), the trapped ions cause a large thermionic current to escape for all biases below the plasma potential. Strong suppression of the thermionic emission, required for the probe to float, only occurs when the probe is above the plasma potential.},
	language = {en},
	number = {1},
	urldate = {2024-04-23},
	journal = {Plasma Sources Science and Technology},
	author = {Johnson, G. R. and Campanell, M. D.},
	month = jan,
	year = {2021},
	pages = {015003},
}

Recent one-dimensional simulations of planar sheaths with strong electron emission have shown that trapping of charge-exchange ions causes transitions from space-charge limited (SCL) to inverse sheaths. However, multidimensional emitting sheath phenomena with collisions remained unexplored, due in part to high computational cost. We developed a novel continuum kinetic code to study the sheath physics, current flow and potential distributions in two-dimensional unmagnetized configurations with emitting surfaces. For small negatively biased thermionic cathodes in a plasma, the cathode sheath can exist in an equilibrium SCL state. The SCL sheath carries an immense density of trapped ions, neutralized by thermoelectrons, within the potential well of the virtual cathode. For further increases of emitted flux, the trapped ion cloud expands in space. The trapped ion space charge causes an increase of thermionic current far beyond the saturation limit predicted by conventional collisionless SCL sheath models without ion trapping. For sufficiently strong emission, the trapped ion cloud consumes the entire 2D plasma domain, forming a mode with globally confined ions and an inverse sheath at the cathode. In situations where the emitted flux is fixed and the bias is swept (e.g. emissive probe), the trapped ions cause a large thermionic current to escape for all biases below the plasma potential. Strong suppression of the thermionic emission, required for the probe to float, only occurs when the probe is above the plasma potential.

@article{deflorio2021,
	title = {Physics-informed neural networks for rarefied-gas dynamics: {Thermal} creep flow in the {Bhatnagar}–{Gross}–{Krook} approximation},
	volume = {33},
	shorttitle = {Physics-informed neural networks for rarefied-gas dynamics},
	doi = {10.1063/5.0046181},
	abstract = {This work aims at accurately solve a thermal creep flow in a plane channel problem, as a class of rarefied-gas dynamics problems, using Physics-Informed Neural Networks (PINNs). We develop a particular PINN framework where the solution of the problem is represented by the Constrained Expressions (CE) prescribed by the recently introduced Theory of Functional Connections (TFC). CEs are represented by a sum of a free-function and a functional (e.g., function of functions) that analytically satisfies the problem constraints regardless to the choice of the free-function. The latter is represented by a shallow Neural Network (NN). Here, the resulting PINN-TFC approach is employed to solve the Boltzmann equation in the Bhatnagar–Gross–Krook approximation modeling the Thermal Creep Flow in a plane channel. We test three different types of shallow NNs, i.e., standard shallow NN, Chebyshev NN (ChNN), and Legendre NN (LeNN). For all the three cases the unknown solutions are computed via the extreme learning machine algorithm. We show that with all these networks we can achieve accurate solutions with a fast training time. In particular, with ChNN and LeNN we are able to match all the available benchmarks.},
	language = {en},
	number = {4},
	urldate = {2024-01-24},
	journal = {Physics of Fluids},
	author = {De Florio, Mario and Schiassi, Enrico and Ganapol, Barry D. and Furfaro, Roberto},
	month = apr,
	year = {2021},
	pages = {047110},
}

This work aims at accurately solve a thermal creep flow in a plane channel problem, as a class of rarefied-gas dynamics problems, using Physics-Informed Neural Networks (PINNs). We develop a particular PINN framework where the solution of the problem is represented by the Constrained Expressions (CE) prescribed by the recently introduced Theory of Functional Connections (TFC). CEs are represented by a sum of a free-function and a functional (e.g., function of functions) that analytically satisfies the problem constraints regardless to the choice of the free-function. The latter is represented by a shallow Neural Network (NN). Here, the resulting PINN-TFC approach is employed to solve the Boltzmann equation in the Bhatnagar–Gross–Krook approximation modeling the Thermal Creep Flow in a plane channel. We test three different types of shallow NNs, i.e., standard shallow NN, Chebyshev NN (ChNN), and Legendre NN (LeNN). For all the three cases the unknown solutions are computed via the extreme learning machine algorithm. We show that with all these networks we can achieve accurate solutions with a fast training time. In particular, with ChNN and LeNN we are able to match all the available benchmarks.

@inproceedings{garbacz2021a,
	title = {{SU2}-{NEMO}: {An} {Open}-{Source} {Framework} for {Nonequilibrium} {Flows}},
	author = {Garbacz, Catrina and Morgado, Fabio and Fossati, Marco and Maier, Walter T and Needels, Jacob and Alonso, Juan J. and Capitelli, M. and Scoggins, James B. and Magin, Thierry E. and Liza, Martin and Hanquist, Kyle M.},
	year = {2021},
}

@article{campbell_evaluation_2021,
	title = {Evaluation of {Computational} {Models} for {Electron} {Transpiration} {Cooling}},
	volume = {8},
	doi = {10.3390/AEROSPACE8090243},
	abstract = {Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.},
	number = {9},
	journal = {Aerospace},
	author = {Campbell, Nicholas S. and Hanquist, Kyle and Morin, Andrew and Meyers, Jason and Boyd, Iain},
	month = sep,
	year = {2021},
	keywords = {equilibrium gas dynamics, gas, hypersonic flight, non, plasma and ionized flows, surface interaction},
}

Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.

@article{petrie_embedded_2021,
	title = {Embedded sensors in additively manufactured silicon carbide},
	volume = {552},
	issn = {0022-3115},
	url = {https://www.sciencedirect.com/science/article/pii/S002231152100235X},
	doi = {10.1016/j.jnucmat.2021.153012},
	abstract = {Silicon carbide (SiC) components are being considered for a wide range of nuclear applications due to their high-temperature strength retention, low neutron absorption, chemical inertness, and dimensional stability under neutron irradiation. However, machining and joining of SiC components have traditionally limited its application to relatively simple geometries. Recent work has demonstrated additive manufacturing of complex, high-purity, crystalline SiC components using a combination of binder jet printing and densification via chemical vapor infiltration (CVI). The process lends itself to embedding of fuel, absorbers, moderators, and sensors at strategic locations within a component. The latter could allow for enhanced in situ performance monitoring of limiting fuel temperatures, self-shielded neutron flux, and potentially spatially distributed strain within complex SiC components if sensors can be successfully embedded during CVI. This work describes (1) methods for embedding sensors; (2) thermodynamic analyses and material compatibility testing for identifying sensors capable of surviving high temperatures and exposure to hydrogen and hydrogen chloride during CVI; and (3) nuclear applications for embedded sensors, including potential failure modes during fabrication and during reactor operation. Molybdenum-sheathed thermocouples were successfully embedded in a complex SiC component, whereas niobium-sheathed high-temperature irradiation-resistant thermocouples started to drift as soon as the reactant gases were introduced and ultimately failed during CVI due to severe constrained expansion, potentially resulting from niobium hydride formation in the low-temperature region of the CVI system. Optical fibers were successfully embedded in SiC, but further work is needed to protect the fragile fiber leads after their protective coatings are removed during CVI.},
	urldate = {2023-10-30},
	journal = {Journal of Nuclear Materials},
	author = {Petrie, Christian M. and Schrell, Adrian M. and Leonard, Donovan N. and Yang, Ying and Jolly, Brian C. and Terrani, Kurt A.},
	month = aug,
	year = {2021},
	keywords = {Additive manufacturing, Embedded, Fiber-optics, Sensors, Silicon carbide, Thermocouples},
	pages = {153012},
}

Silicon carbide (SiC) components are being considered for a wide range of nuclear applications due to their high-temperature strength retention, low neutron absorption, chemical inertness, and dimensional stability under neutron irradiation. However, machining and joining of SiC components have traditionally limited its application to relatively simple geometries. Recent work has demonstrated additive manufacturing of complex, high-purity, crystalline SiC components using a combination of binder jet printing and densification via chemical vapor infiltration (CVI). The process lends itself to embedding of fuel, absorbers, moderators, and sensors at strategic locations within a component. The latter could allow for enhanced in situ performance monitoring of limiting fuel temperatures, self-shielded neutron flux, and potentially spatially distributed strain within complex SiC components if sensors can be successfully embedded during CVI. This work describes (1) methods for embedding sensors; (2) thermodynamic analyses and material compatibility testing for identifying sensors capable of surviving high temperatures and exposure to hydrogen and hydrogen chloride during CVI; and (3) nuclear applications for embedded sensors, including potential failure modes during fabrication and during reactor operation. Molybdenum-sheathed thermocouples were successfully embedded in a complex SiC component, whereas niobium-sheathed high-temperature irradiation-resistant thermocouples started to drift as soon as the reactant gases were introduced and ultimately failed during CVI due to severe constrained expansion, potentially resulting from niobium hydride formation in the low-temperature region of the CVI system. Optical fibers were successfully embedded in SiC, but further work is needed to protect the fragile fiber leads after their protective coatings are removed during CVI.

@article{monton_experimental_2021,
	title = {Experimental and numerical study for direct powder bed selective laser processing (sintering/melting) of silicon carbide ceramic},
	volume = {8},
	issn = {2053-1591},
	doi = {10.1088/2053-1591/abf6fc},
	abstract = {The study was carried out to investigate the manufacturing possibility of Silicon Carbide (SiC) by direct Powder Bed Selective Laser Processing (PBSLP) experimentally and numerically. The experimental study was carried out by means of PBSLP while the numerical study was accomplished by developing a CFD model. The CFD model simulates accurately realistic conditions of the PBSLP process. A user-defined code, that describes the process parameters such as laser power, scanning speed, scanning strategies, and hatching distance has been developed and compiled to ANSYS FLUENT 2020 R1. Also, the model was validated with the available published data from the literature. The model was used to deeply analyse and support the results obtained through the experimental runs. Different values of laser power and scanning speeds with scanning strategy in the form of a continuous linear pattern and rotated by 90 degrees between layers were studied. The laser power is ranging from 52W to 235 W while the scanning speed is ranging from 300 to 3900 mm s−1. The results showed that the direct PBSLP of SiC is possible with the optimization of the process parameters. Layer thickness and hatching distance are the most important parameters that needed to be optimized. Also, the laser power and scanning speed needed to be adjusted so that the scanning temperature was between the sintering and the decomposition limits. The good agreement between experimental and simulation results proved the power and ability of the developed CFD model to be a useful tool to analyse and optimize future experimental data.},
	language = {en},
	number = {4},
	urldate = {2023-10-28},
	journal = {Materials Research Express},
	author = {Montón, Alejandro and Abdelmoula, Mohammed and Küçüktürk, Gökhan and Maury, Francis and Grossin, David and Ferrato, Marc},
	month = apr,
	year = {2021},
	note = {Publisher: IOP Publishing},
	pages = {045603},
}

The study was carried out to investigate the manufacturing possibility of Silicon Carbide (SiC) by direct Powder Bed Selective Laser Processing (PBSLP) experimentally and numerically. The experimental study was carried out by means of PBSLP while the numerical study was accomplished by developing a CFD model. The CFD model simulates accurately realistic conditions of the PBSLP process. A user-defined code, that describes the process parameters such as laser power, scanning speed, scanning strategies, and hatching distance has been developed and compiled to ANSYS FLUENT 2020 R1. Also, the model was validated with the available published data from the literature. The model was used to deeply analyse and support the results obtained through the experimental runs. Different values of laser power and scanning speeds with scanning strategy in the form of a continuous linear pattern and rotated by 90 degrees between layers were studied. The laser power is ranging from 52W to 235 W while the scanning speed is ranging from 300 to 3900 mm s−1. The results showed that the direct PBSLP of SiC is possible with the optimization of the process parameters. Layer thickness and hatching distance are the most important parameters that needed to be optimized. Also, the laser power and scanning speed needed to be adjusted so that the scanning temperature was between the sintering and the decomposition limits. The good agreement between experimental and simulation results proved the power and ability of the developed CFD model to be a useful tool to analyse and optimize future experimental data.

@article{mostafaei_binder_2021,
	title = {Binder jet {3D} printing—{Process} parameters, materials, properties, modeling, and challenges},
	volume = {119},
	issn = {0079-6425},
	url = {https://www.sciencedirect.com/science/article/pii/S0079642520300712},
	doi = {10.1016/j.pmatsci.2020.100707},
	abstract = {As a non-beam-based additive manufacturing (AM) method, binder jet 3D printing (BJ3DP) is a process in which a liquid binder is jetted on layers of powdered materials, selectively joined, and then followed by densification process. Among AM technologies, binder jetting holds distinctive promise because of the possibility of rapid production of complex structures to achieve isotropic properties in the 3D printed samples. By taking advantage of traditional powder metallurgy, BJ3DP machines can produce prototypes in which material properties and surface finish are similar to those attained with traditional powder metallurgy. Various powdered materials have been 3D printed, but a typical challenge during BJ3DP is developing printing and post-processing methods that maximize part performance. Therefore, a detailed review of the physical processes during 3D printing and the fundamental science of densification after sintering and post–heat treatment steps are provided to understand the microstructural evolution and properties of binder jetted parts. Furthermore, to determine the effects of the binder jetting process on metallurgical properties, the role of powder characteristics (e.g., morphology, mean size, distribution), printing process parameters (e.g., layer thickness, print orientation, binder saturation, print speed, drying time), sintering (e.g., temperature, holding time), and post-processing are discussed. With the development of AM technologies and the need for post-processing in 3D printed parts, understanding the microstructural evolution during densification is necessary and here, processing steps are explained. Finally, opportunities for future advancement are addressed.},
	urldate = {2023-10-28},
	journal = {Progress in Materials Science},
	author = {Mostafaei, Amir and Elliott, Amy M. and Barnes, John E. and Li, Fangzhou and Tan, Wenda and Cramer, Corson L. and Nandwana, Peeyush and Chmielus, Markus},
	month = jun,
	year = {2021},
	keywords = {Additive manufacturing, Binder, Ceramic, Composite, Indirect 3D printing, Infiltration, Materials selection, Metal, Post-processing, Powder bed, Powder characteristics, Print processing parameters, Sintering},
	pages = {100707},
}

As a non-beam-based additive manufacturing (AM) method, binder jet 3D printing (BJ3DP) is a process in which a liquid binder is jetted on layers of powdered materials, selectively joined, and then followed by densification process. Among AM technologies, binder jetting holds distinctive promise because of the possibility of rapid production of complex structures to achieve isotropic properties in the 3D printed samples. By taking advantage of traditional powder metallurgy, BJ3DP machines can produce prototypes in which material properties and surface finish are similar to those attained with traditional powder metallurgy. Various powdered materials have been 3D printed, but a typical challenge during BJ3DP is developing printing and post-processing methods that maximize part performance. Therefore, a detailed review of the physical processes during 3D printing and the fundamental science of densification after sintering and post–heat treatment steps are provided to understand the microstructural evolution and properties of binder jetted parts. Furthermore, to determine the effects of the binder jetting process on metallurgical properties, the role of powder characteristics (e.g., morphology, mean size, distribution), printing process parameters (e.g., layer thickness, print orientation, binder saturation, print speed, drying time), sintering (e.g., temperature, holding time), and post-processing are discussed. With the development of AM technologies and the need for post-processing in 3D printed parts, understanding the microstructural evolution during densification is necessary and here, processing steps are explained. Finally, opportunities for future advancement are addressed.

@article{koyanagi_additive_2021,
	title = {Additive manufacturing of silicon carbide for nuclear applications},
	volume = {543},
	issn = {0022-3115},
	url = {https://www.sciencedirect.com/science/article/pii/S0022311520311855},
	doi = {10.1016/j.jnucmat.2020.152577},
	abstract = {Additive manufacturing (AM) is a rapidly evolving technology being considered for nuclear applications. A special focus on AM to fabricate nuclear-grade silicon carbide (SiC) is explored in this paper. First, we present currently available AM processing options for SiC. AM methods commonly used for other ceramics, in which the feedstocks are forms of polymers, powders, and/or reactive chemical vapors, are also applicable to SiC. SiC phases are formed by pyrolysis of pre-ceramic polymer, direct reaction of powder precursors, sintering of SiC powders, or chemical vapor deposition/infiltration. Second, we discuss how the different microstructures of SiC materials fabricated by various processing methods affect their behavior in nuclear environments. Third, we discuss state-of-the-art AM technologies for the fabrication of relatively pure SiC, which show great potential to retain its strength under neutron irradiation: (1) binder jet printing followed by chemical vapor infiltration, (2) laser chemical vapor deposition, and (3) selective laser sintering of SiC powders.},
	urldate = {2023-10-28},
	journal = {Journal of Nuclear Materials},
	author = {Koyanagi, Takaaki and Terrani, Kurt and Harrison, Shay and Liu, Jian and Katoh, Yutai},
	month = jan,
	year = {2021},
	keywords = {Silicon carbide, additive manufacturing, microstructure, neutron irradiation, swelling},
	pages = {152577},
}

Additive manufacturing (AM) is a rapidly evolving technology being considered for nuclear applications. A special focus on AM to fabricate nuclear-grade silicon carbide (SiC) is explored in this paper. First, we present currently available AM processing options for SiC. AM methods commonly used for other ceramics, in which the feedstocks are forms of polymers, powders, and/or reactive chemical vapors, are also applicable to SiC. SiC phases are formed by pyrolysis of pre-ceramic polymer, direct reaction of powder precursors, sintering of SiC powders, or chemical vapor deposition/infiltration. Second, we discuss how the different microstructures of SiC materials fabricated by various processing methods affect their behavior in nuclear environments. Third, we discuss state-of-the-art AM technologies for the fabrication of relatively pure SiC, which show great potential to retain its strength under neutron irradiation: (1) binder jet printing followed by chemical vapor infiltration, (2) laser chemical vapor deposition, and (3) selective laser sintering of SiC powders.

@article{he_progress_2021,
	title = {Progress and challenges towards additive manufacturing of {SiC} ceramic},
	volume = {10},
	issn = {2227-8508},
	doi = {10.1007/s40145-021-0484-z},
	abstract = {Silicon carbide (SiC) ceramic and related materials are widely used in various military and engineering fields. The emergence of additive manufacturing (AM) technologies provides a new approach for the fabrication of SiC ceramic products. This article systematically reviews the additive manufacturing technologies of SiC ceramic developed in recent years, including Indirect Additive Manufacturing (Indirect AM) and Direct Additive Manufacturing (Direct AM) technologies. This review also summarizes the key scientific and technological challenges for the additive manufacturing of SiC ceramic, and also forecasts its possible future opportunities. This paper aims to provide a helpful guidance for the additive manufacturing of SiC ceramic and other structural ceramics.},
	language = {en},
	number = {4},
	urldate = {2023-10-28},
	journal = {Journal of Advanced Ceramics},
	author = {He, Rujie and Zhou, Niping and Zhang, Keqiang and Zhang, Xueqin and Zhang, Lu and Wang, Wenqing and Fang, Daining},
	month = aug,
	year = {2021},
	keywords = {additive manufacturing (AM), silicon carbide (SiC), structural ceramics},
	pages = {637--674},
}

Silicon carbide (SiC) ceramic and related materials are widely used in various military and engineering fields. The emergence of additive manufacturing (AM) technologies provides a new approach for the fabrication of SiC ceramic products. This article systematically reviews the additive manufacturing technologies of SiC ceramic developed in recent years, including Indirect Additive Manufacturing (Indirect AM) and Direct Additive Manufacturing (Direct AM) technologies. This review also summarizes the key scientific and technological challenges for the additive manufacturing of SiC ceramic, and also forecasts its possible future opportunities. This paper aims to provide a helpful guidance for the additive manufacturing of SiC ceramic and other structural ceramics.

@article{grover2021,
	title = {\textit{{Ab} initio} simulation of hypersonic flows past a cylinder based on accurate potential energy surfaces},
	volume = {33},
	issn = {1070-6631, 1089-7666},
	doi = {10.1063/5.0047945},
	abstract = {For the first time in the literature, we present 2D simulations of hypersonic flows around a cylinder obtained from accurate ab initio potential energy surfaces (PESs). We compare results obtained from a low fidelity (empirical) and a high fidelity (ab initio) PES, thus demonstrating the impact of PES accuracy on the entire aerothermodynamic field around the body. We observe that the empirical PES is not adequate to accurately reproduce rotational and vibrational relaxation in the hypersonic flow, both in the compression and expansion regions of the flow field. This approach, enabled by advancements in large-scale computing, paves the way to the direct simulation of hypersonic flows where the only modeling input is the PES that describes molecular interactions between the various air constituents. Such flow field simulations provide benchmark solutions for the validation of reduced-order models.},
	language = {en},
	number = {5},
	urldate = {2023-09-08},
	journal = {Physics of Fluids},
	author = {Grover, Maninder S. and Valentini, Paolo},
	month = may,
	year = {2021},
	pages = {051704},
}

For the first time in the literature, we present 2D simulations of hypersonic flows around a cylinder obtained from accurate ab initio potential energy surfaces (PESs). We compare results obtained from a low fidelity (empirical) and a high fidelity (ab initio) PES, thus demonstrating the impact of PES accuracy on the entire aerothermodynamic field around the body. We observe that the empirical PES is not adequate to accurately reproduce rotational and vibrational relaxation in the hypersonic flow, both in the compression and expansion regions of the flow field. This approach, enabled by advancements in large-scale computing, paves the way to the direct simulation of hypersonic flows where the only modeling input is the PES that describes molecular interactions between the various air constituents. Such flow field simulations provide benchmark solutions for the validation of reduced-order models.

@article{streicher2021,
	title = {Coupled vibration-dissociation time-histories and rate measurements in shock-heated, nondilute {O2} and {O2}–{Ar} mixtures from 6000 to 14 000 {K}},
	volume = {33},
	issn = {1070-6631},
	url = {https://doi.org/10.1063/5.0048059},
	doi = {10.1063/5.0048059},
	abstract = {Validation of high-fidelity models for high-temperature hypersonic flows requires high-accuracy kinetics data for oxygen (O2) reactions, including time-histories and rate parameter measurements. Consequently, shock-tube experiments with ultraviolet (UV) laser absorption were performed to measure quantum-state-specific time-histories and coupled vibration-dissociation (CVDV) rate parameters in shock-heated, nondilute O2 and oxygen–argon (O2–Ar) mixtures. Experiments probed mixtures of 20\% O2–Ar, 50\% O2–Ar, and 100\% O2 for initial post-reflected-shock conditions from 6000 to 14 000 K and 26–210 Torr. Two UV lasers—one continuous-wave laser and one pulsed laser—measured absorbance time-histories from the fifth and sixth vibrational levels of the electronic ground state of O2, respectively. The absorbance time-histories subsequently yielded time-histories for vibrational temperature (Tv) from the absorbance ratio, translational/rotational temperature (Ttr) from energy conservation, total O2 number density (nO2) from the individual absorbances, and vibrational-state-specific number density (nv″) from the Boltzmann population fractions. These state-specific temperature and number density time-histories demonstrate the low uncertainty necessary for high-temperature model validation and provide data to higher temperature than previous experiments. Additional analysis of the temperature and number density time-histories allowed inference of rate parameters in the Marrone and Treanor CVDV model, including vibrational relaxation time (τO2−O2), average vibrational energy loss (ε), vibrational coupling factor (Z), and dissociation rate constants (kdO2−O2 and kdO2−O). The results for each of these five parameters show reasonable consistency across the range of temperatures, pressures, and mixtures and generally agree with a modified Marrone and Treanor model by Chaudhry et al. [“Implementation of a chemical kinetics model for hypersonic flows in air for high-performance CFD,” in Proceedings of AIAA Scitech Forum (2020)]. Finally, the results for τO2−O2, kdO2−O2, and kdO2−O exhibit much lower scatter than previous experimental studies.},
	number = {5},
	urldate = {2023-08-10},
	journal = {Physics of Fluids},
	author = {Streicher, Jesse W. and Krish, Ajay and Hanson, Ronald K.},
	month = may,
	year = {2021},
	pages = {056107},
}

Validation of high-fidelity models for high-temperature hypersonic flows requires high-accuracy kinetics data for oxygen (O2) reactions, including time-histories and rate parameter measurements. Consequently, shock-tube experiments with ultraviolet (UV) laser absorption were performed to measure quantum-state-specific time-histories and coupled vibration-dissociation (CVDV) rate parameters in shock-heated, nondilute O2 and oxygen–argon (O2–Ar) mixtures. Experiments probed mixtures of 20% O2–Ar, 50% O2–Ar, and 100% O2 for initial post-reflected-shock conditions from 6000 to 14 000 K and 26–210 Torr. Two UV lasers—one continuous-wave laser and one pulsed laser—measured absorbance time-histories from the fifth and sixth vibrational levels of the electronic ground state of O2, respectively. The absorbance time-histories subsequently yielded time-histories for vibrational temperature (Tv) from the absorbance ratio, translational/rotational temperature (Ttr) from energy conservation, total O2 number density (nO2) from the individual absorbances, and vibrational-state-specific number density (nv″) from the Boltzmann population fractions. These state-specific temperature and number density time-histories demonstrate the low uncertainty necessary for high-temperature model validation and provide data to higher temperature than previous experiments. Additional analysis of the temperature and number density time-histories allowed inference of rate parameters in the Marrone and Treanor CVDV model, including vibrational relaxation time (τO2−O2), average vibrational energy loss (ε), vibrational coupling factor (Z), and dissociation rate constants (kdO2−O2 and kdO2−O). The results for each of these five parameters show reasonable consistency across the range of temperatures, pressures, and mixtures and generally agree with a modified Marrone and Treanor model by Chaudhry et al. [“Implementation of a chemical kinetics model for hypersonic flows in air for high-performance CFD,” in Proceedings of AIAA Scitech Forum (2020)]. Finally, the results for τO2−O2, kdO2−O2, and kdO2−O exhibit much lower scatter than previous experimental studies.

@article{neely2021,
	title = {High-{Speed} {FSI} {Databases} - {Unit} {Cases}},
	url = {https://www.unsw.adfa.edu.au/high-speed-fsi-database-unit-cases},
	journal = {UNSW Canberra},
	author = {Neely, Andrew},
	year = {2021},
}

@article{sasidharan2021,
	title = {Large- and small-amplitude shock-wave oscillations over axisymmetric bodies in high-speed flow},
	volume = {913},
	doi = {10.1017/JFM.2021.115},
	abstract = {The phenomena of self-sustained shock-wave oscillations over conical bodies with a blunt axisymmetric base subject to uniform high-speed flow are investigated in a hypersonic wind tunnel at Mach number . The flow and shock-wave dynamics is dictated by two non-dimensional geometric parameters presented by the three length scales of the body, two of which are associated with the conical forebody and one with the base. Time-resolved schlieren imagery from these experiments reveals the presence of two disparate states of shock-wave oscillations in the flow, and allows for the mapping of unsteadiness boundaries in the two-parameter space. Physical mechanisms are proposed to explain the oscillations and the transitions of the shock-wave system from steady to oscillatory states. In comparison with the canonical single-parameter problem of shock-wave oscillations over spiked-blunt bodies reported in literature, the two-parameter nature of the present problem introduces distinct elements to the flow dynamics.},
	journal = {Journal of Fluid Mechanics},
	author = {Sasidharan, Vaisakh and Duvvuri, Subrahmanyam},
	year = {2021},
	note = {Publisher: Cambridge University Press},
	keywords = {high-speed flow, shock waves},
}

The phenomena of self-sustained shock-wave oscillations over conical bodies with a blunt axisymmetric base subject to uniform high-speed flow are investigated in a hypersonic wind tunnel at Mach number . The flow and shock-wave dynamics is dictated by two non-dimensional geometric parameters presented by the three length scales of the body, two of which are associated with the conical forebody and one with the base. Time-resolved schlieren imagery from these experiments reveals the presence of two disparate states of shock-wave oscillations in the flow, and allows for the mapping of unsteadiness boundaries in the two-parameter space. Physical mechanisms are proposed to explain the oscillations and the transitions of the shock-wave system from steady to oscillatory states. In comparison with the canonical single-parameter problem of shock-wave oscillations over spiked-blunt bodies reported in literature, the two-parameter nature of the present problem introduces distinct elements to the flow dynamics.

@inproceedings{sadagopan2021,
	title = {Assessment of {High}-{Temperature} {Effects} on {Hypersonic} {Aerothermoelastic} {Analysis} using {Multi}-{Fidelity} {Multi}-{Variate} {Surrogates}},
	isbn = {978-1-62410-609-5},
	doi = {10.2514/6.2021-1610},
	abstract = {This study investigates the impact of the high-temperature effect, esp. the real gas effect and the chemical reactions, on hypersonic aerothermodynamic solutions of double cone and double wedge configurations, as well as the aerothermoelastic behavior of a double wedge configuration in hypersonic flow. First, a high-temperature computational fluid dynamics code was benchmarked and correlated with experimental results, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, an aerothermal surrogate based on the multi-fidelity Gaussian process regression method was developed. The model achieves a balance between model accuracy and computational cost of sample generation, using the combination of a few high-fidelity sample and many low-fidelity samples. Finally, the new aerothermal surrogate was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, emphasizing the necessity of the accurate characterization of the localized heat flux for reasonable assessment of the response of a compliant structure in high-speed high-temperature flowfield.},
	publisher = {AIAA Paper 2021-1610},
	author = {Sadagopan, Aravinth and Huang, Daning and Martin, Liza E. and Hanquist, Kyle M.},
	month = jan,
	year = {2021},
}

This study investigates the impact of the high-temperature effect, esp. the real gas effect and the chemical reactions, on hypersonic aerothermodynamic solutions of double cone and double wedge configurations, as well as the aerothermoelastic behavior of a double wedge configuration in hypersonic flow. First, a high-temperature computational fluid dynamics code was benchmarked and correlated with experimental results, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, an aerothermal surrogate based on the multi-fidelity Gaussian process regression method was developed. The model achieves a balance between model accuracy and computational cost of sample generation, using the combination of a few high-fidelity sample and many low-fidelity samples. Finally, the new aerothermal surrogate was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, emphasizing the necessity of the accurate characterization of the localized heat flux for reasonable assessment of the response of a compliant structure in high-speed high-temperature flowfield.

@article{tang2021,
	title = {Enhanced thermionic emission of mayenite electride composites in an {Ar} glow discharge plasma},
	volume = {47},
	issn = {0272-8842},
	doi = {10.1016/j.ceramint.2021.02.233},
	abstract = {Mayenite electride has attracted increasing research interests because of its unique electronic properties. The thermionic emission behavior of the mayenite electride is relatively unknown. Previous studies revealed that mayenite electride exhibited a bare work function ranged from 2.1–2.6 eV when the thermionic emission was tested in vacuum, and enhanced emission currents could be achieved by applying a super-high external electric field. In this paper, the thermionic emission behavior and the corresponding effective work function of two types of mayenite electride based composites, mayenite electride-titanium and mayenite electride-carbon, were investigated in an Ar glow discharge plasma at elevated temperatures (400–1000 K) without applying a high external electric field, which is critical for the application in electric propulsion and other aerospace apparatus, yet never had been done before. During the testing, the thermal equilibrium process and plasma sheath expansion were observed. The effective work function of the two mayenite electride composites were determined as a function of temperature. The Rasor-Warner model was applied to determine the bare work function and adsorption-site density of the mayenite electride based composites. Results suggested that the adsorption of Ar ions led to the enhanced thermionic emission ({\textasciitilde}30 A/m2 at 985 K) and low effective work functions (0.9–2.2 eV) of mayenite electride based composites, without the need of applying high electric fields. Our findings will pave the ways for the application of mayenite electride and its composites as the thrust cathode materials for electric propulsion where plasma is present.},
	language = {en},
	number = {12},
	urldate = {2023-07-05},
	journal = {Ceramics International},
	author = {Tang, Xiaochuan and Kuehster, Adam E. and DeBoer, Brodderic A. and Preston, Alexander D. and Ma, Kaka},
	month = jun,
	year = {2021},
	keywords = {Effective work function, Glow discharge plasma, Mayenite electride, Thermionic emission},
	pages = {16614--16631},
}

Mayenite electride has attracted increasing research interests because of its unique electronic properties. The thermionic emission behavior of the mayenite electride is relatively unknown. Previous studies revealed that mayenite electride exhibited a bare work function ranged from 2.1–2.6 eV when the thermionic emission was tested in vacuum, and enhanced emission currents could be achieved by applying a super-high external electric field. In this paper, the thermionic emission behavior and the corresponding effective work function of two types of mayenite electride based composites, mayenite electride-titanium and mayenite electride-carbon, were investigated in an Ar glow discharge plasma at elevated temperatures (400–1000 K) without applying a high external electric field, which is critical for the application in electric propulsion and other aerospace apparatus, yet never had been done before. During the testing, the thermal equilibrium process and plasma sheath expansion were observed. The effective work function of the two mayenite electride composites were determined as a function of temperature. The Rasor-Warner model was applied to determine the bare work function and adsorption-site density of the mayenite electride based composites. Results suggested that the adsorption of Ar ions led to the enhanced thermionic emission (~30 A/m2 at 985 K) and low effective work functions (0.9–2.2 eV) of mayenite electride based composites, without the need of applying high electric fields. Our findings will pave the ways for the application of mayenite electride and its composites as the thrust cathode materials for electric propulsion where plasma is present.

@inproceedings{footohi2021a,
	title = {Wingtip {Jets} {Effects} on {Flow} {Entrainment} and {Aerodynamic} {Loads}},
	doi = {10.2514/6.2021-2812},
	booktitle = {{AIAA} {AVIATION} 2021 {FORUM}},
	publisher = {AIAA Paper 2021-2812},
	author = {Footohi, Parisa and Mozzone, Luciano and Shkarayev, Sergey V. and Hanquist, Kyle M.},
	year = {2021},
	doi = {10.2514/6.2021-2812},
	keywords = {Aerodynamic Force Coefficients, Aspect Ratio, Computational Fluid Dynamics Simulation, Data Acquisition, Internal Flows, Lift Coefficient, NACA 0012, Pressure Coefficient, Wind Tunnel Models, Wingtip Vortices, own},
}

@inproceedings{gross2021,
	address = {VIRTUAL EVENT},
	title = {Wall-{Modeled} {Large}-{Eddy} {Simulations} of {Turbulent} {Shockwave} {Boundary} {Layer} {Interaction} and {Boundary} {Layer} {Flows}},
	isbn = {978-1-62410-610-1},
	doi = {10.2514/6.2021-2749},
	language = {en},
	urldate = {2023-01-12},
	booktitle = {{AIAA} {AVIATION} 2021 {FORUM}},
	publisher = {AIAA Paper 2021-2749},
	author = {Gross, Andreas and Castillo Gomez, Pedro and Lee, Sunyoung},
	month = aug,
	year = {2021},
}

@article{gallis2021a,
	title = {Turbulence at the edge of continuum},
	volume = {6},
	issn = {2469-990X},
	doi = {10.1103/PhysRevFluids.6.013401},
	language = {en},
	number = {1},
	urldate = {2023-01-12},
	journal = {Physical Review Fluids},
	author = {Gallis, M. A. and Torczynski, J. R. and Krygier, M. C. and Bitter, N. P. and Plimpton, S. J.},
	month = jan,
	year = {2021},
	pages = {013401},
}

@misc{hanquist2021,
	address = {Department of Mechanical Engineering, University of Kentucky},
	type = {Invited {Seminar}},
	title = {Thermal {Management} of {Hot} {Aerospace} {Surfaces} using {Plasma} {Assisted} {Cooling}},
	author = {Hanquist, Kyle M.},
	year = {2021},
	keywords = {invited, own},
}

@misc{garbacz2021,
	address = {SU2 Conference 2021},
	title = {{SU2}-{NEMO}: {An} {Open}-{Source} {Framework} for {Nonequilibrium} {Flows}},
	author = {Garbacz, Catrina and Morgado, Fabio and Fossati, Marco and Maier, Walter T and Needels, Jacob and Alonso, Juan J. and Capitelli, M. and Scoggins, James B. and Magin, Thierry E. and Liza, Martin E. and Hanquist, Kyle M.},
	year = {2021},
	keywords = {own, presentation},
}

@article{maier2021a,
	title = {{SU2}-{NEMO}: {An} {Open}-{Source} {Framework} for {High}-{Mach} {Nonequilibrium} {Multi}-{Species} {Flows}},
	volume = {8},
	url = {https://www.mdpi.com/2226-4310/8/7/193/htm},
	doi = {10.3390/AEROSPACE8070193},
	abstract = {SU2-NEMO, a recent extension of the open-source SU2 multiphysics suite’s set of physical models and code architecture, is presented with the aim of introducing its enhanced capabilities in addressing high-enthalpy and high-Mach number flows. This paper discusses the thermal nonequilibrium and finite-rate chemistry models adopted, including a link to the Mutation++ physio-chemical library. Further, the paper discusses how the software architecture has been designed to ensure modularity, incorporating the ability to introduce additional models in an efficient manner. A review of the numerical formulation and the discretization schemes utilized for the convective fluxes is also presented. Several test cases in two- and three-dimensions are examined for validation purposes and to illustrate the performance of the solver in addressing complex nonequilibrium flows.},
	number = {7},
	journal = {Aerospace 2021, Vol. 8, Page 193},
	author = {Maier, Walter T. and Needels, Jacob T. and Garbacz, Catarina and Morgado, Fábio and Alonso, Juan J. and Fossati, Marco},
	month = jul,
	year = {2021},
	note = {Publisher: Multidisciplinary Digital Publishing Institute},
	keywords = {aerothermodynamics, computational fluid dynamics, high, hypersonic flight, nonequilibrium flows, temperature effects},
	pages = {193--193},
}

SU2-NEMO, a recent extension of the open-source SU2 multiphysics suite’s set of physical models and code architecture, is presented with the aim of introducing its enhanced capabilities in addressing high-enthalpy and high-Mach number flows. This paper discusses the thermal nonequilibrium and finite-rate chemistry models adopted, including a link to the Mutation++ physio-chemical library. Further, the paper discusses how the software architecture has been designed to ensure modularity, incorporating the ability to introduce additional models in an efficient manner. A review of the numerical formulation and the discretization schemes utilized for the convective fluxes is also presented. Several test cases in two- and three-dimensions are examined for validation purposes and to illustrate the performance of the solver in addressing complex nonequilibrium flows.

@article{maier2021,
	title = {{SU2}-{NEMO}: {An} {Open}-{Source} {Framework} for {High}-{Mach} {Nonequilibrium} {Multi}-{Species} {Flows}},
	volume = {8},
	doi = {10.3390/aerospace8070193},
	abstract = {SU2-NEMO, a recent extension of the open-source SU2 multiphysics suite’s set of physical models and code architecture, is presented with the aim of introducing its enhanced capabilities in addressing high-enthalpy and high-Mach number flows. This paper discusses the thermal nonequilibrium and finite-rate chemistry models adopted, including a link to the Mutation++ physio-chemical library. Further, the paper discusses how the software architecture has been designed to ensure modularity, incorporating the ability to introduce additional models in an efficient manner. A review of the numerical formulation and the discretization schemes utilized for the convective fluxes is also presented. Several test cases in two- and three-dimensions are examined for validation purposes and to illustrate the performance of the solver in addressing complex nonequilibrium flows.},
	language = {en},
	number = {7},
	urldate = {2023-05-04},
	journal = {Aerospace},
	author = {Maier, Walter T. and Needels, Jacob T. and Garbacz, Catarina and Morgado, Fábio and Alonso, Juan J. and Fossati, Marco},
	year = {2021},
	keywords = {aerothermodynamics, computational fluid dynamics, high-temperature effects, hypersonic flight, nonequilibrium flows},
	pages = {193},
}

SU2-NEMO, a recent extension of the open-source SU2 multiphysics suite’s set of physical models and code architecture, is presented with the aim of introducing its enhanced capabilities in addressing high-enthalpy and high-Mach number flows. This paper discusses the thermal nonequilibrium and finite-rate chemistry models adopted, including a link to the Mutation++ physio-chemical library. Further, the paper discusses how the software architecture has been designed to ensure modularity, incorporating the ability to introduce additional models in an efficient manner. A review of the numerical formulation and the discretization schemes utilized for the convective fluxes is also presented. Several test cases in two- and three-dimensions are examined for validation purposes and to illustrate the performance of the solver in addressing complex nonequilibrium flows.

@article{parent2021d,
	title = {Plasma {Sheath} {Modelling} for {Computational} {Aerothermodynamics} and {Magnetohydrodynamics}},
	volume = {35},
	doi = {10.1080/10618562.2021.1949456},
	abstract = {To date, plasma sheath effects have not been incorporated into most CFD simulations of magnetohydrodynamics (MHD) or aerothermodynamics due to the high computational costs involved. The accurate mo...},
	number = {5},
	journal = {International Journal of Computational Fluid Dynamics},
	author = {Parent, Bernard and Hanquist, Kyle M.},
	year = {2021},
	keywords = {Plasma sheath, electron transpiration cooling, hypersonic flight, magnetohydrodynamics, own, re-entry flows},
	pages = {331--348},
}

To date, plasma sheath effects have not been incorporated into most CFD simulations of magnetohydrodynamics (MHD) or aerothermodynamics due to the high computational costs involved. The accurate mo...

@article{campbell2021b,
	title = {Progress {Toward} {High} {Power} {Output} in {Thermionic} {Energy} {Converters}},
	volume = {8},
	doi = {10.1002/ADVS.202003812},
	abstract = {Thermionic energy converters are solid-state heat engines that have the potential to produce electricity with efficiencies of over 30\% and area-specific power densities of 100 Wcm−2. Despite this prospect, no prototypes reported in the literature have achieved true efficiencies close to this target, and many of the most recent investigations report power densities on the order of mWcm−2 or less. These discrepancies stem in part from the low-temperature ({\textless}1300 K) test conditions used to evaluate these devices, the large vacuum gap distances (25–100 µm) employed by these devices, and material challenges related to these devices' electrodes. This review will argue that, for feasible electrode work functions available today, efficient performance requires generating output power densities of {\textgreater}1 Wcm−2 and employing emitter temperatures of 1300 K or higher. With this result in mind, this review provides an overview of historical and current design architectures and comments on their capacity to realize the efficiency and power potential of thermionic energy converters. Also emphasized is the importance of using standardized efficiency metrics to report thermionic energy converter performance data.},
	number = {9},
	journal = {Advanced Science},
	author = {Campbell, Matthew F. and Celenza, Thomas J. and Schmitt, Felix and Schwede, Jared W. and Bargatin, Igor},
	year = {2021},
	keywords = {efficiency, heat transfer, power density, thermionic energy conversion},
}

Thermionic energy converters are solid-state heat engines that have the potential to produce electricity with efficiencies of over 30% and area-specific power densities of 100 Wcm−2. Despite this prospect, no prototypes reported in the literature have achieved true efficiencies close to this target, and many of the most recent investigations report power densities on the order of mWcm−2 or less. These discrepancies stem in part from the low-temperature (\textless1300 K) test conditions used to evaluate these devices, the large vacuum gap distances (25–100 µm) employed by these devices, and material challenges related to these devices' electrodes. This review will argue that, for feasible electrode work functions available today, efficient performance requires generating output power densities of \textgreater1 Wcm−2 and employing emitter temperatures of 1300 K or higher. With this result in mind, this review provides an overview of historical and current design architectures and comments on their capacity to realize the efficiency and power potential of thermionic energy converters. Also emphasized is the importance of using standardized efficiency metrics to report thermionic energy converter performance data.

@article{bandari2021,
	title = {Preventing a communication blackout in spacecraft during reentry},
	volume = {2021},
	url = {https://aip.scitation.org/doi/abs/10.1063/10.0003770},
	doi = {10.1063/10.0003770},
	abstract = {A two-layer metamaterial with optimized permeability and permittivity placed between the plasma surrounding an aircraft and an antenna located in its interior can help prevent radio wave attenuatio...},
	number = {10},
	journal = {Scilight},
	author = {Bandari, Anashe},
	month = mar,
	year = {2021},
	note = {Publisher: AIP Publishing LLC AIP Publishing},
}

A two-layer metamaterial with optimized permeability and permittivity placed between the plasma surrounding an aircraft and an antenna located in its interior can help prevent radio wave attenuatio...

@article{garbacz2021b,
	title = {Parametric study of nonequilibrium shock interference patterns over a fuselage-and-wing conceptual vehicle},
	volume = {59},
	doi = {10.2514/1.J060470},
	abstract = {Predicting shock/shock and shock/boundary-layer interactions in gas flows that surround high-speed vehicles is key in aerodynamic design. Under typical hypersonic conditions, these flow structures are influenced by complex nonequilibrium phenomena leading to high-temperature effects. In this work, the conceptual Bedford wing-body vehicle is studied to analyze flow patterns in shock/shock and shock/boundary-layer interactions with thermochemical nonequilibrium. A parametric computational fluid dynamics study is carried out for different hypersonic operating conditions, with respect to the freestream Mach number. Simulations are performed with the SU2-NEMO solver coupled to the Mutation++ library, which provides all the necessary thermodynamic, kinetic, and transport properties of the mixture and chemical species. The Adaptive Mesh Generation library is used for automatic anisotropic mesh adaptation. Numerical results show that increasing the freestream Mach number from 4 to 10 leads to changes in the shock layer, locations of shock impingement, and regions of boundary-layer separation. Despite these changes, the change in freestream Mach number has little impact on the overall shock interaction structures.},
	number = {12},
	journal = {AIAA Journal},
	author = {Garbacz, Catarina and Morgado, Fábio and Fossati, Marco and Maier, Walter T. and Munguía, Brian C. and Alonso, Juan J. and Loseille, Adrien},
	month = dec,
	year = {2021},
	note = {Publisher: AIAA International},
	keywords = {Aerodynamic Coefficients, Attached Shock Wave, Boundary Layer Interaction, CFD Simulation, High Lift Device, Lift Coefficient, Mesh Generation, Nonequilibrium Flows, Temperature Effects, Vibrational Energy},
	pages = {4905--4916},
}

Predicting shock/shock and shock/boundary-layer interactions in gas flows that surround high-speed vehicles is key in aerodynamic design. Under typical hypersonic conditions, these flow structures are influenced by complex nonequilibrium phenomena leading to high-temperature effects. In this work, the conceptual Bedford wing-body vehicle is studied to analyze flow patterns in shock/shock and shock/boundary-layer interactions with thermochemical nonequilibrium. A parametric computational fluid dynamics study is carried out for different hypersonic operating conditions, with respect to the freestream Mach number. Simulations are performed with the SU2-NEMO solver coupled to the Mutation++ library, which provides all the necessary thermodynamic, kinetic, and transport properties of the mixture and chemical species. The Adaptive Mesh Generation library is used for automatic anisotropic mesh adaptation. Numerical results show that increasing the freestream Mach number from 4 to 10 leads to changes in the shock layer, locations of shock impingement, and regions of boundary-layer separation. Despite these changes, the change in freestream Mach number has little impact on the overall shock interaction structures.

@inproceedings{evans2021,
	title = {Performance of an sfrj with an aft-mixing section utilizing bypass air},
	isbn = {978-1-62410-609-5},
	url = {https://arc.aiaa.org/doi/10.2514/6.2021-1876},
	doi = {10.2514/6.2021-1876},
	abstract = {The effect of secondary injection of air downstream of the combustor of a model solid-fuel ramjet (SFRJ) combustor on its global performance is studied. The SFRJ is operated with heated non-vitiated air (2 = 387-727 °F, = 2.31-3.81 lbm/s) and cylindrical, center-perforated HTPB fuel grains. The secondary air bypass ratio is varied from 0-30\%. For comparable operating conditions, the use of the aft-mixing section (AMS) resulted in an improvement in combustion efficiency from ∼85\% to ∼95\% and increase in from ∼110 s to ∼130 s. The bypass air was introduced into the AMS using circumferential jet injection at momentum flux ratios of 3-3.5 and 20. For comparable operating conditions, the = 20 cases had a slightly lower combustion efficiency than the = 3-3.5 cases. The jet trajectory and heat-release in the AMS were characterized using broadband chemiluminescence performed at 6 kHz and CH* chemiluminescence performed at 50 kHz.},
	publisher = {AIAA Paper 2021-1876},
	author = {Evans, Jay V. and Senior, William C.B. and Gejji, Rohan M. and Strahan, Nicholas L. and Slabaugh, Carson D.},
	year = {2021},
	pages = {1--10},
}

The effect of secondary injection of air downstream of the combustor of a model solid-fuel ramjet (SFRJ) combustor on its global performance is studied. The SFRJ is operated with heated non-vitiated air (2 = 387-727 °F, = 2.31-3.81 lbm/s) and cylindrical, center-perforated HTPB fuel grains. The secondary air bypass ratio is varied from 0-30%. For comparable operating conditions, the use of the aft-mixing section (AMS) resulted in an improvement in combustion efficiency from ∼85% to ∼95% and increase in from ∼110 s to ∼130 s. The bypass air was introduced into the AMS using circumferential jet injection at momentum flux ratios of 3-3.5 and 20. For comparable operating conditions, the = 20 cases had a slightly lower combustion efficiency than the = 3-3.5 cases. The jet trajectory and heat-release in the AMS were characterized using broadband chemiluminescence performed at 6 kHz and CH* chemiluminescence performed at 50 kHz.

@inproceedings{needels2021,
	title = {Interpretation of {Vehicle} {Tumbling} {Predictions} {From} 6-{DOF} {Entry} and {Descent} {Simulation}},
	author = {Needels, J. and Gage, P. and Hill, J.},
	year = {2021},
}

@misc{hanquist2021a,
	address = {Department of Aerospace \& Mechanical Engineering, New Mexico State University},
	type = {Invited {Seminar}},
	title = {Importance of {Modeling} in {Hypersonic} {Flight} {Conditions}},
	author = {Hanquist, Kyle M.},
	year = {2021},
	keywords = {invited, own},
}

@inproceedings{sawicki2021,
	title = {Influence of chemical kinetics models on plasma generation in hypersonic flight},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2021-0057},
	doi = {10.2514/6.2021-0057},
	abstract = {The accuracy and sensitivity of plasma generation predicted by several different chemical kinetics models is investigated in the context of weakly ionized hypersonic flowfields around the RAM-C (Ra-dio Attenuation Measurement) vehicle. A computational fluid dynamics analysis is used to examine thirteen independent trajectory points along the RAM-C II flight and an assessment of the chemistry models is made by comparing results to available flight measurements. The limitations of making such comparisons with the flight data are established in detail. Two separate geometries are evaluated in this study, as the initial RAM-C geometry was altered during flight after its nose-cap was pyrotechnically ejected. The blunter post-ejection geometry generates more electrons in the stagnation region. In general, good agreement is found between each chemistry model and flight data from both the electrostatic probe and reflectometer stations above 56 km. An expected sizable gap exists between the simulations and reflectometer data at lower altitudes. The impact of forward reaction rates, equilibrium constants, and number of species varies considerably based on altitude, velocity, and position along the body. The commonly analyzed 61 km trajectory point provides a more direct comparison of the various chemistry models, but due care must be given to account for the interpola-tive nature of the reflectometer measurements.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Sawicki, Pawel and Chaudhry, Ross S. and Boyd, Iain D.},
	year = {2021},
	pages = {1--16},
}

The accuracy and sensitivity of plasma generation predicted by several different chemical kinetics models is investigated in the context of weakly ionized hypersonic flowfields around the RAM-C (Ra-dio Attenuation Measurement) vehicle. A computational fluid dynamics analysis is used to examine thirteen independent trajectory points along the RAM-C II flight and an assessment of the chemistry models is made by comparing results to available flight measurements. The limitations of making such comparisons with the flight data are established in detail. Two separate geometries are evaluated in this study, as the initial RAM-C geometry was altered during flight after its nose-cap was pyrotechnically ejected. The blunter post-ejection geometry generates more electrons in the stagnation region. In general, good agreement is found between each chemistry model and flight data from both the electrostatic probe and reflectometer stations above 56 km. An expected sizable gap exists between the simulations and reflectometer data at lower altitudes. The impact of forward reaction rates, equilibrium constants, and number of species varies considerably based on altitude, velocity, and position along the body. The commonly analyzed 61 km trajectory point provides a more direct comparison of the various chemistry models, but due care must be given to account for the interpola-tive nature of the reflectometer measurements.

@article{ortega2021,
	title = {Inequitable {Access} to {Graduate} {School} {Is} {Holding} {Back} the {Economy}},
	journal = {Barron's},
	author = {Ortega, Suzanne T},
	year = {2021},
}

@article{torres2021,
	title = {How to build coarse-grain transport models consistent from the kinetic to fluid regimes},
	volume = {33},
	doi = {10.1063/5.0037133},
	abstract = {In this paper, we examine how to build coarse-grain transport models consistently from the kinetic to fluid regimes. The internal energy of the gas particles is described through a state-to-state a...},
	number = {3},
	journal = {Physics of Fluids},
	author = {Torres, Erik and Bellas-Chatzigeorgis, Georgios and Magin, Thierry E.},
	month = mar,
	year = {2021},
	note = {Publisher: AIP Publishing LLC AIP Publishing},
}

In this paper, we examine how to build coarse-grain transport models consistently from the kinetic to fluid regimes. The internal energy of the gas particles is described through a state-to-state a...

@article{bhattrai2021,
	title = {Experimental {Study} of {Aeroelastic} {Response} and {Performance} of a {Hypersonic} {Intake} {Ramp}},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.B38348},
	doi = {10.2514/1.B38348},
	abstract = {The response and performance of an aeroelastic hypersonic intake was studied experimentally using fundamental geometry and structural boundary conditions. The experiments were conducted in a hypers...},
	journal = {Journal of Propulsion and Power},
	author = {Bhattrai, Sudip and McQuellin, Liam P. and Currao, Gaetano M. D. and Neely, Andrew J. and Buttsworth, David R.},
	month = sep,
	year = {2021},
	note = {Publisher: American Institute of Aeronautics and Astronautics},
	keywords = {Aeroelastic Response, Boundary Layer Separation, Cantilever Beam, Hysteresis, Mach Cones, Pitot Probes, Pressure Sensitive Paint, Pressure Transducers, Reynolds Averaged Navier Stokes, Structural Response},
	pages = {1--14},
}

The response and performance of an aeroelastic hypersonic intake was studied experimentally using fundamental geometry and structural boundary conditions. The experiments were conducted in a hypers...

@inproceedings{venegas2021,
	title = {Expedient {Hypersonic} {Aerothermal} {Prediction} for {Aerothermoelastic} {Analysis} {Via} {Field} {Inversion} and {Machine} {Learning}},
	doi = {10.2514/6.2021-1707},
	abstract = {The accurate and efficient prediction of aerothermal loads over the hypersonic vehicles during atmospheric flight is critical for the aerothermoelastic design, analysis and optimization of the structures of this class of vehicles. Reduced-order models (ROMs) and surrogates are typical approaches to reducing the computational cost to a tractable level. However, the existing ROMs and surrogates suffer from the curse of dimensionality that roots from the need to parameterize and sample the thermal-structural responses. This work presents a novel physics-informed ROM for the aerothermal load calculation on a deforming structure in high-speed flow, based on the combination of the classical turbulent viscous-inviscid interaction (TVI) model and the field inversion and machine learning technique. It is demonstrated that the new model, termed augmented TVI model, can achieve an accuracy close to that of CFD solvers when predicting the flow solutions over a wide range of complex surface deformations with a limited number of high-fidelity solutions. These results underline its potential to be used as a new generation of ROM for the aerothermal load prediction in hypersonic aerothermoelastic design and analysis.},
	publisher = {AIAA Paper 2021-1707},
	author = {Venegas, Carlos Vargas and Huang, Daning},
	year = {2021},
}

The accurate and efficient prediction of aerothermal loads over the hypersonic vehicles during atmospheric flight is critical for the aerothermoelastic design, analysis and optimization of the structures of this class of vehicles. Reduced-order models (ROMs) and surrogates are typical approaches to reducing the computational cost to a tractable level. However, the existing ROMs and surrogates suffer from the curse of dimensionality that roots from the need to parameterize and sample the thermal-structural responses. This work presents a novel physics-informed ROM for the aerothermal load calculation on a deforming structure in high-speed flow, based on the combination of the classical turbulent viscous-inviscid interaction (TVI) model and the field inversion and machine learning technique. It is demonstrated that the new model, termed augmented TVI model, can achieve an accuracy close to that of CFD solvers when predicting the flow solutions over a wide range of complex surface deformations with a limited number of high-fidelity solutions. These results underline its potential to be used as a new generation of ROM for the aerothermal load prediction in hypersonic aerothermoelastic design and analysis.

@article{campbell2021,
	title = {Evaluation of {Computational} {Models} for {Electron} {Transpiration} {Cooling}},
	volume = {8},
	doi = {10.3390/AEROSPACE8090243},
	abstract = {Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.},
	number = {9},
	journal = {Aerospace},
	author = {Campbell, Nicholas S. and Hanquist, Kyle M. and Morin, Andrew and Meyers, Jason and Boyd, Iain},
	year = {2021},
	keywords = {equilibrium gas dynamics, gas, hypersonic flight, non, own, plasma and ionized flows, surface interaction},
}

Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.

@article{parent2021c,
	title = {Electron heating and cooling in hypersonic flows},
	volume = {33},
	doi = {10.1063/5.0046197},
	abstract = {Using recently developed advanced numerical methods for plasma flows and sheaths, the first detailed study of electron cooling and heating taking place within hypersonic non-neutral flows is presen...},
	number = {4},
	journal = {Physics of Fluids},
	author = {Parent, B.},
	month = apr,
	year = {2021},
	note = {Publisher: AIP Publishing LLC AIP Publishing},
	pages = {046105--046105},
}

Using recently developed advanced numerical methods for plasma flows and sheaths, the first detailed study of electron cooling and heating taking place within hypersonic non-neutral flows is presen...

@inproceedings{parent2021b,
	title = {Effect of cesium seeding on plasma density in hypersonic boundary layers},
	doi = {10.2514/6.2021-1251},
	abstract = {© 2021, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This paper outlines the effect of cesium seeding on the plasma density within the boundary layer around a wedge with a sharp leading edge in the Mach number range 6–18. The results are obtained through numerical simulation using two CFD codes, LeMANS and CFDWARP, which include finite-rate chemistry, non-equilibrium of the vibrational and electron energies, and real gas effects. Results obtained indicate that seeding the air flow with as little as 0.001\% of cesium leads to plasma densities high enough to interfere with radio communication and to enable electron transpiration cooling (ETC) at flight Mach numbers as little as 9. When no cesium is added, it is seen that significant interference of the plasma on radio communication can occur in the Mach number range 12–18, with the interference becoming more likely for higher flight dynamic pressure.},
	booktitle = {{AIAA} {SCITECH} 2021 {Forum}},
	publisher = {AIAA Paper 2021-1251},
	author = {Parent, Bernard and Hanquist, Kyle M. and Rajendran, Prasanna T. and Liza, Martin E.},
	year = {2021},
	keywords = {own},
}

© 2021, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This paper outlines the effect of cesium seeding on the plasma density within the boundary layer around a wedge with a sharp leading edge in the Mach number range 6–18. The results are obtained through numerical simulation using two CFD codes, LeMANS and CFDWARP, which include finite-rate chemistry, non-equilibrium of the vibrational and electron energies, and real gas effects. Results obtained indicate that seeding the air flow with as little as 0.001% of cesium leads to plasma densities high enough to interfere with radio communication and to enable electron transpiration cooling (ETC) at flight Mach numbers as little as 9. When no cesium is added, it is seen that significant interference of the plasma on radio communication can occur in the Mach number range 12–18, with the interference becoming more likely for higher flight dynamic pressure.

@article{gallis2021,
	title = {Effect of slip on vortex shedding from a circular cylinder in a gas flow},
	volume = {6},
	url = {https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.6.063402},
	doi = {10.1103/PHYSREVFLUIDS.6.063402},
	abstract = {Most studies of vortex shedding from a circular cylinder in a gas flow have explicitly or implicitly assumed that the no-slip condition applies on the cylinder surface. To investigate the effect of slip, vortex shedding is simulated using molecular gas dynamics (the direct simulation Monte Carlo method) and computational fluid dynamics (the incompressible Navier-Stokes equations with a slip boundary condition). A Reynolds number of 100, a Mach number of 0.3, and a corresponding Knudsen number of 0.0048 are examined. For these conditions, compressibility effects are small, and periodic laminar vortex shedding is obtained. Slip on the cylinder is varied using combinations of diffuse and specular molecular reflections with accommodation coefficients from zero (maximum slip) to unity (minimum slip). Although unrealistic, bounce-back molecular reflections are also examined because they approximate the no-slip boundary condition (zero slip). The results from both methods are in reasonable agreement. The shedding frequency increases slightly as the accommodation coefficient is decreased, and shedding ceases at low accommodation coefficients (large slip). The streamwise and transverse forces decrease as the accommodation coefficient is decreased. Based on the good agreement between the two methods, computational fluid dynamics is used to determine the critical accommodation coefficient below which vortex shedding ceases for Reynolds numbers of 60-100 at a Mach number of 0.3. Conditions to observe the effect of slip on vortex shedding appear to be experimentally realizable, although challenging.},
	number = {6},
	journal = {Physical Review Fluids},
	author = {Gallis, M. A. and Torczynski, J. R.},
	month = jun,
	year = {2021},
	note = {Publisher: American Physical Society},
	pages = {063402--063402},
}

Most studies of vortex shedding from a circular cylinder in a gas flow have explicitly or implicitly assumed that the no-slip condition applies on the cylinder surface. To investigate the effect of slip, vortex shedding is simulated using molecular gas dynamics (the direct simulation Monte Carlo method) and computational fluid dynamics (the incompressible Navier-Stokes equations with a slip boundary condition). A Reynolds number of 100, a Mach number of 0.3, and a corresponding Knudsen number of 0.0048 are examined. For these conditions, compressibility effects are small, and periodic laminar vortex shedding is obtained. Slip on the cylinder is varied using combinations of diffuse and specular molecular reflections with accommodation coefficients from zero (maximum slip) to unity (minimum slip). Although unrealistic, bounce-back molecular reflections are also examined because they approximate the no-slip boundary condition (zero slip). The results from both methods are in reasonable agreement. The shedding frequency increases slightly as the accommodation coefficient is decreased, and shedding ceases at low accommodation coefficients (large slip). The streamwise and transverse forces decrease as the accommodation coefficient is decreased. Based on the good agreement between the two methods, computational fluid dynamics is used to determine the critical accommodation coefficient below which vortex shedding ceases for Reynolds numbers of 60-100 at a Mach number of 0.3. Conditions to observe the effect of slip on vortex shedding appear to be experimentally realizable, although challenging.

@misc{chengalrayan2021,
	address = {74th Annual Meeting of the Division of Fluid Dynamics, American Physical Society},
	type = {Conference {Presentation}},
	title = {Determination of {Flow} {Field} and {Structural} {Parameters} using {Inverse} {Interpolation} {Methods}},
	author = {Chengalrayan, Sruthi and Pascual, Rodrigo and Shkarayev, Sergey V. and Hanquist, Kyle M.},
	year = {2021},
	keywords = {own, presentation},
}

@article{venturi2020a,
	title = {Data-{Inspired} and {Physics}-{Driven} {Model} {Reduction} for {Dissociation}: {Application} to the {O}$_{\textrm{2}}$+{O} {System}},
	volume = {124},
	url = {https://pubs.acs.org/doi/full/10.1021/acs.jpca.0c04516},
	doi = {10.1021/ACS.JPCA.0C04516/ASSET/IMAGES/MEDIUM/JP0C04516_M040.GIF},
	abstract = {This work presents an in-depth discussion on the nonequilibrium dissociation of O2 molecules colliding with O atoms, combining quasi-classical trajectory calculations, master equation, and dimensionality reduction. A rovibrationally resolved database for all of the elementary collisional processes is constructed by including all nine adiabatic electronic states of O3 in the QCT calculations. A detailed analysis of the ab initio data set reveals that for a rovibrational level, the probability of dissociating is mostly dictated by its deficit in internal energy compared to the centrifugal barrier. Because of the assumption of rotational equilibrium, the conventional vibrational-specific calculations fail to characterize such a dependence. Based on this observation, a new physics-based grouping strategy for application to coarse-grained models is proposed. By relying on a hybrid technique made of rovibrationally resolved excitation coupled to coarse-grained dissociation, the new approach is compared to the vibrational-specific model and the direct solution of the rovibrational state-to-state master equation. Simulations are performed in a zero-dimensional isothermal and isochoric chemical reactor for a wide range of temperatures (1500-20,000 K). The study shows that the main contribution to the model inadequacy of vibrational-specific approaches originates from the incapability of characterizing dissociation, rather than the energy transfers. Even when constructed with only twenty groups, the new reduced-order model outperforms the vibrational-specific one in predicting all of the QoIs related to dissociation kinetics. At the highest temperature, the accuracy in the mole fraction is improved by 2000\%.},
	number = {41},
	journal = {Journal of Physical Chemistry A},
	author = {Venturi, S. and Sharma, M. P. and Lopez, B. and Panesi, M.},
	month = oct,
	year = {2020},
	note = {Publisher: American Chemical Society},
	pages = {8359--8372},
}

This work presents an in-depth discussion on the nonequilibrium dissociation of O2 molecules colliding with O atoms, combining quasi-classical trajectory calculations, master equation, and dimensionality reduction. A rovibrationally resolved database for all of the elementary collisional processes is constructed by including all nine adiabatic electronic states of O3 in the QCT calculations. A detailed analysis of the ab initio data set reveals that for a rovibrational level, the probability of dissociating is mostly dictated by its deficit in internal energy compared to the centrifugal barrier. Because of the assumption of rotational equilibrium, the conventional vibrational-specific calculations fail to characterize such a dependence. Based on this observation, a new physics-based grouping strategy for application to coarse-grained models is proposed. By relying on a hybrid technique made of rovibrationally resolved excitation coupled to coarse-grained dissociation, the new approach is compared to the vibrational-specific model and the direct solution of the rovibrational state-to-state master equation. Simulations are performed in a zero-dimensional isothermal and isochoric chemical reactor for a wide range of temperatures (1500-20,000 K). The study shows that the main contribution to the model inadequacy of vibrational-specific approaches originates from the incapability of characterizing dissociation, rather than the energy transfers. Even when constructed with only twenty groups, the new reduced-order model outperforms the vibrational-specific one in predicting all of the QoIs related to dissociation kinetics. At the highest temperature, the accuracy in the mole fraction is improved by 2000%.

@inproceedings{wignall2020,
	title = {Uncertainty {Quantification} for {Launch} {Vehicle} {Aerodynamic} {Lineloads}},
	doi = {10.2514/6.2020-1521},
	booktitle = {{AIAA} {Scitech} {Forum}},
	author = {Wignall, T and Houlden, Heather},
	month = jan,
	year = {2020},
}

@techreport{urzay2020,
	title = {Engineering aspects of hypersonic turbulent flows at suborbital enthalpies},
	url = {https://web.stanford.edu/~jurzay/hypersonicsCh2_Urzay.pdf},
	language = {en},
	number = {Center for Turbulence Research, Annual Research Briefs},
	institution = {Stanford University},
	author = {Urzay, J and Renzo, M Di},
	year = {2020},
}

@inproceedings{tropina2020,
	title = {Modeling studies of electron transpiration cooling at high-speed flows},
	doi = {10.2514/6.2020-3231},
	publisher = {AIAA Paper 2020-3231},
	author = {Tropina, Albina and Andrienko, Daniil A and Miles, Richard B},
	year = {2020},
	keywords = {etc},
}

@article{bailey2020,
	title = {Frequent and {Reliable} {Launch} for {Small} {Satellites}: {Rocket} {Lab}'s {Electron} {Launch} {Vehicle} and {Photon} {Spacecraft}},
	doi = {https://doi.org/10.1007/978-3-030-36308-6_91#DOI},
	journal = {Handbook of Small Satellites},
	author = {Bailey, Morgan},
	month = sep,
	year = {2020},
	pages = {453--468},
}

@article{Yao2020,
	title = {Influence of {LOS} angle on aero-optics imaging deviation},
	volume = {202},
	issn = {00304026},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0030402619316304},
	doi = {10.1016/j.ijleo.2019.163732},
	journal = {Optik},
	author = {Yao, Yuan and Xue, Wei and Wang, Tao and Wu, Yuyang and Xu, Liang},
	month = feb,
	year = {2020},
	pages = {163732},
}

@inproceedings{sadagopan2020,
	title = {Impact of high-temperature effects on the aerothermoelastic behavior of composite skin panels in hypersonic flow},
	doi = {10.2514/6.2020-0937},
	abstract = {© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This study investigates the impact of the high-temperature effect, esp. the real gas effect and the chemical reactions, on hypersonic aerothermodynamic solutions and the aerothermoelastic behavior of a typical skin panel in hypersonic flow. First, several computational fluid dynamics codes that were developed in significantly different ways were benchmarked and compared for hypersonic aerothermodynamics, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, a reduced-order model (ROM) for hypersonic aerothermal loads accounting for the high-temperature effect is developed. Particularly, a ROM correction approach for high-temperature effect was presented, so that a ROM constructed based on the perfect gas assumption can generate fluid solutions that account for the real gas effect with reasonable accuracy. Finally, the new fluid ROM was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, with an emphasis on its stability boundary.},
	booktitle = {{AIAA} {SCITEH} 2020 {Forum}},
	publisher = {AIAA Paper 2020-0937},
	author = {Sadagopan, A. and Huang, D. and Hanquist, K.},
	year = {2020},
	keywords = {own},
}

© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This study investigates the impact of the high-temperature effect, esp. the real gas effect and the chemical reactions, on hypersonic aerothermodynamic solutions and the aerothermoelastic behavior of a typical skin panel in hypersonic flow. First, several computational fluid dynamics codes that were developed in significantly different ways were benchmarked and compared for hypersonic aerothermodynamics, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, a reduced-order model (ROM) for hypersonic aerothermal loads accounting for the high-temperature effect is developed. Particularly, a ROM correction approach for high-temperature effect was presented, so that a ROM constructed based on the perfect gas assumption can generate fluid solutions that account for the real gas effect with reasonable accuracy. Finally, the new fluid ROM was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, with an emphasis on its stability boundary.

@inproceedings{macdonald2020a,
	title = {Initial {Characterization} of the 30 {kW} {Miniature} {Arc} {Jet} ({mARC} {II}) at {NASA} {Ames} {Research} {Center}},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2020-3108},
	abstract = {The second-generation Miniature Arc jet Research Chamber (mARC II) at NASA Ames is undergoing integrated systems testing. Once fully operational, this facility will be added to the range of available test facilities operated by the NASA Ames Thermophysics Facilities Branch, with primary focus on applications such as new arc jet flow diagnostics and new arc column diagnostics. Initial characterization of the mARC II is reported here, specifically, measured arc current, arc voltage, column and chamber pressures, mass flow rates, and initial emission measurements carried out at a range of conditions.},
	urldate = {2024-04-26},
	booktitle = {{AIAA} {AVIATION} 2020 {FORUM}},
	publisher = {AIAA Paper 2020-3108},
	author = {MacDonald, Megan E. and Philippidis, Daniel and Haw, Magnus and Schickele, Daniel and Luis, Diana and Hartman, Joe and McGlaughlin, Mark},
	year = {2020},
}

The second-generation Miniature Arc jet Research Chamber (mARC II) at NASA Ames is undergoing integrated systems testing. Once fully operational, this facility will be added to the range of available test facilities operated by the NASA Ames Thermophysics Facilities Branch, with primary focus on applications such as new arc jet flow diagnostics and new arc column diagnostics. Initial characterization of the mARC II is reported here, specifically, measured arc current, arc voltage, column and chamber pressures, mass flow rates, and initial emission measurements carried out at a range of conditions.

@article{leake2020,
	title = {Deep {Theory} of {Functional} {Connections}: {A} {New} {Method} for {Estimating} the {Solutions} of {Partial} {Differential} {Equations}},
	volume = {2},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	issn = {2504-4990},
	shorttitle = {Deep {Theory} of {Functional} {Connections}},
	doi = {10.3390/make2010004},
	abstract = {This article presents a new methodology called Deep Theory of Functional Connections (TFC) that estimates the solutions of partial differential equations (PDEs) by combining neural networks with the TFC. The TFC is used to transform PDEs into unconstrained optimization problems by analytically embedding the PDE’s constraints into a “constrained expression” containing a free function. In this research, the free function is chosen to be a neural network, which is used to solve the now unconstrained optimization problem. This optimization problem consists of minimizing a loss function that is chosen to be the square of the residuals of the PDE. The neural network is trained in an unsupervised manner to minimize this loss function. This methodology has two major differences when compared with popular methods used to estimate the solutions of PDEs. First, this methodology does not need to discretize the domain into a grid, rather, this methodology can randomly sample points from the domain during the training phase. Second, after training, this methodology produces an accurate analytical approximation of the solution throughout the entire training domain. Because the methodology produces an analytical solution, it is straightforward to obtain the solution at any point within the domain and to perform further manipulation if needed, such as differentiation. In contrast, other popular methods require extra numerical techniques if the estimated solution is desired at points that do not lie on the discretized grid, or if further manipulation to the estimated solution must be performed.},
	language = {en},
	number = {1},
	urldate = {2024-04-24},
	journal = {Machine Learning and Knowledge Extraction},
	author = {Leake, Carl and Mortari, Daniele},
	month = mar,
	year = {2020},
	keywords = {deep learning, neural network, partial differential equation, theory of functional connections},
	pages = {37--55},
}

This article presents a new methodology called Deep Theory of Functional Connections (TFC) that estimates the solutions of partial differential equations (PDEs) by combining neural networks with the TFC. The TFC is used to transform PDEs into unconstrained optimization problems by analytically embedding the PDE’s constraints into a “constrained expression” containing a free function. In this research, the free function is chosen to be a neural network, which is used to solve the now unconstrained optimization problem. This optimization problem consists of minimizing a loss function that is chosen to be the square of the residuals of the PDE. The neural network is trained in an unsupervised manner to minimize this loss function. This methodology has two major differences when compared with popular methods used to estimate the solutions of PDEs. First, this methodology does not need to discretize the domain into a grid, rather, this methodology can randomly sample points from the domain during the training phase. Second, after training, this methodology produces an accurate analytical approximation of the solution throughout the entire training domain. Because the methodology produces an analytical solution, it is straightforward to obtain the solution at any point within the domain and to perform further manipulation if needed, such as differentiation. In contrast, other popular methods require extra numerical techniques if the estimated solution is desired at points that do not lie on the discretized grid, or if further manipulation to the estimated solution must be performed.

@article{baalrud2020,
	title = {Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs},
	volume = {29},
	issn = {0963-0252},
	shorttitle = {Interaction of biased electrodes and plasmas},
	doi = {10.1088/1361-6595/ab8177},
	abstract = {Biased electrodes are common components of plasma sources and diagnostics. The plasma–electrode interaction is mediated by an intervening sheath structure that influences properties of the electrons and ions contacting the electrode surface, as well as properties of the bulk plasma. A rich variety of sheath structures have been observed, including ion sheaths, electron sheaths, double sheaths, double layers, anode glow, and fireballs. These represent complex self-organized responses of the plasma that depend not only on the local influence of the electrode, but also on the global properties of the plasma and the other boundaries that it is in contact with. This review summarizes recent advances in understanding the conditions under which each type of sheath forms, what the basic stability criteria and steady-state properties of each are, and the ways in which each can influence plasma–boundary interactions and bulk plasma properties. These results may be of interest to a number of application areas where biased electrodes are used, including diagnostics, plasma modification of materials, plasma sources, electric propulsion, and the interaction of plasmas with objects in space.},
	language = {en},
	number = {5},
	urldate = {2024-04-24},
	journal = {Plasma Sources Science and Technology},
	author = {Baalrud, Scott D. and Scheiner, Brett and Yee, Benjamin T. and Hopkins, Matthew M. and Barnat, Edward},
	month = may,
	year = {2020},
	pages = {053001},
}

Biased electrodes are common components of plasma sources and diagnostics. The plasma–electrode interaction is mediated by an intervening sheath structure that influences properties of the electrons and ions contacting the electrode surface, as well as properties of the bulk plasma. A rich variety of sheath structures have been observed, including ion sheaths, electron sheaths, double sheaths, double layers, anode glow, and fireballs. These represent complex self-organized responses of the plasma that depend not only on the local influence of the electrode, but also on the global properties of the plasma and the other boundaries that it is in contact with. This review summarizes recent advances in understanding the conditions under which each type of sheath forms, what the basic stability criteria and steady-state properties of each are, and the ways in which each can influence plasma–boundary interactions and bulk plasma properties. These results may be of interest to a number of application areas where biased electrodes are used, including diagnostics, plasma modification of materials, plasma sources, electric propulsion, and the interaction of plasmas with objects in space.

@article{adams2020,
	title = {Dakota, a multilevel parallel object-oriented framework for design optimization, parameter estimation, uncertainty quantification, and sensitivity analysis: {Version} 6.13 user's manual},
	doi = {10.2172/1817318},
	author = {Adams, Brian M. and Bohnhoff, William J. and Dalbey, Keith R. and Ebeida, Mohamed S. and Eddy, John P. and Eldred, Michael S. and Hooper, Russell W. and Hough, Patricia D. and Hu, Kenneth T. and Jakeman, John D. and Khalil, Mohammad and Maupin, Kathryn A. and Monschke, Jason A. and Ridgway, Elliott M. and Rushdi, Ahmad . and Seidl, Daniel Thomas and Stephens, John Adam and Winokur, Justin G.},
	month = nov,
	year = {2020},
}

@article{blanco2020,
	title = {Numerical {Modeling} of {Hypersonic} {Weakly} {Ionized} {External} {Flowfields} with {Poisson}’s {Equation}},
	volume = {58},
	doi = {10.2514/1.J059307},
	abstract = {A seven-species air model is used to numerically simulate and analyze the flowfield of an air plasma. Previous numerical models have employed different electric field approximations that assume amb...},
	number = {8},
	journal = {AIAA Journal},
	author = {Blanco, Ariel and Josyula, Eswar},
	month = may,
	year = {2020},
	keywords = {Courant Friedrichs Lewy, Freestream Velocity, No Slip Condition, Nonequilibrium Flows, Nonequilibrium Plasmas, Numerical Modeling, Poisson's Equation, Shock Layers, Thermal Flux, Velocity Distribution Function},
	pages = {3464--3475},
}

A seven-species air model is used to numerically simulate and analyze the flowfield of an air plasma. Previous numerical models have employed different electric field approximations that assume amb...

@article{terrani_3d_2020,
	title = {{3D} printing of high-purity silicon carbide},
	volume = {103},
	copyright = {Published 2019. This article is a U.S. Government work and is in the public domain in the USA.},
	issn = {1551-2916},
	doi = {10.1111/jace.16888},
	abstract = {A method for advanced manufacturing of silicon carbide offering complete freedom in geometric complexity in the three-dimensional space is described. The method combines binder jet printing and chemical vapor infiltration in a process capable of yielding a high-purity, fully crystalline ceramic—attributes essential for ideal performance in very high-temperature applications or in the presence of displacement damage. Thermal conductivity and characteristic equibiaxial flexural strength of the resulting monolithic SiC at room temperature are 37 W·(m·K)−1 and 297 MPa, respectively.},
	language = {en},
	number = {3},
	urldate = {2023-10-30},
	journal = {Journal of the American Ceramic Society},
	author = {Terrani, Kurt and Jolly, Brian and Trammell, Michael},
	year = {2020},
	note = {\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jace.16888},
	keywords = {3D printing, processing, silicon carbide},
	pages = {1575--1581},
}

A method for advanced manufacturing of silicon carbide offering complete freedom in geometric complexity in the three-dimensional space is described. The method combines binder jet printing and chemical vapor infiltration in a process capable of yielding a high-purity, fully crystalline ceramic—attributes essential for ideal performance in very high-temperature applications or in the presence of displacement damage. Thermal conductivity and characteristic equibiaxial flexural strength of the resulting monolithic SiC at room temperature are 37 W·(m·K)−1 and 297 MPa, respectively.

@article{song_performance_2020,
	title = {Performance optimization of complicated structural {SiC}/{Si} composite ceramics prepared by selective laser sintering},
	volume = {46},
	issn = {0272-8842},
	doi = {10.1016/j.ceramint.2019.09.004},
	abstract = {Combining reaction-bonded (RB) process and selective laser sintering (SLS) method is an effective approach to prepare ceramic components with complex shapes. The purpose of this paper is to find efficient ways to improve the performance of SiC/Si composites prepared by SLS/RB technologies. Effects of epoxy resin binder on the performance and microstructure of preforms and sintered bodies were studied first. Then, based on the above results, graphite with low reactivity was used as an alternative slow-release carbon source to promote sintering densification process and improve the carbon density of preforms. When the added amount of graphite increased, clusters of nanometer-sized SiC grains formed and the silicon phase transformed into pieces, which reduced the content and dimension of silicon phase. Furthermore, by applying a two-step sintering method, the residual silicon content of SiC/Si composites decreased further and the flexural strength at high temperatures increased.},
	number = {1},
	urldate = {2023-10-28},
	journal = {Ceramics International},
	author = {Song, Suocheng and Gao, Zongqiang and Lu, Bingheng and Bao, Chonggao and Zheng, Baochao and Wang, Lei},
	month = jan,
	year = {2020},
	keywords = {High-temperature behavior, Performance enchantment, Reaction-bonded process, Selective laser sintering},
	pages = {568--575},
}

Combining reaction-bonded (RB) process and selective laser sintering (SLS) method is an effective approach to prepare ceramic components with complex shapes. The purpose of this paper is to find efficient ways to improve the performance of SiC/Si composites prepared by SLS/RB technologies. Effects of epoxy resin binder on the performance and microstructure of preforms and sintered bodies were studied first. Then, based on the above results, graphite with low reactivity was used as an alternative slow-release carbon source to promote sintering densification process and improve the carbon density of preforms. When the added amount of graphite increased, clusters of nanometer-sized SiC grains formed and the silicon phase transformed into pieces, which reduced the content and dimension of silicon phase. Furthermore, by applying a two-step sintering method, the residual silicon content of SiC/Si composites decreased further and the flexural strength at high temperatures increased.

@article{xu_high-temperature_2020,
	title = {High-temperature flexural strength of {SiC} ceramics prepared by additive manufacturing},
	volume = {17},
	copyright = {© 2019 The American Ceramic Society},
	issn = {1744-7402},
	doi = {10.1111/ijac.13454},
	abstract = {Silicon carbide (SiC) ceramics, as a kind of candidate material for aero-engine, its high-temperature performance is a critical factor to determine its applicability. This investigation focuses on studying the high-temperature properties of SiC ceramics fabricated by using additive manufacturing technology. In this paper, SiC ceramics were prepared by combining selective laser sintering (SLS) with precursor infiltration and pyrolysis (PIP) technique. The microstructure, phase evolution, and failure mechanism after high-temperature tests were explored. SiC ceramic samples tested at room temperature (RT), 800°C, 1200°C, 1400°C, and 1600°C demonstrated bending strengths of 220.0, 226.1, 234.9, 215.5, and 203.7 MPa, respectively. The RT strength of this material can be maintained at 1400°C, but it decreased at 1600°C. The strength retention at 1400°C and 1600°C were 98\% and 92\%, respectively. The results indicate that the mechanical properties of SiC ceramics prepared using this method have excellent stability. As the temperature increases, the bending strength of the specimens increased slightly and reached the peak value at 1200°C, and dropped to 203.7 MPa at 1600°C. Such an evolution could be mainly due to the crack healing, and the softening of the glassy phase.},
	language = {en},
	number = {2},
	urldate = {2023-10-23},
	journal = {International Journal of Applied Ceramic Technology},
	author = {Xu, Teng-Teng and Cheng, Su and Jin, Lai-Zhen and Zhang, Kun and Zeng, Tao},
	year = {2020},
	keywords = {high-temperature flexural strength, polymer impregnation process, selective laser sintering, silicon carbide},
	pages = {438--448},
}

Silicon carbide (SiC) ceramics, as a kind of candidate material for aero-engine, its high-temperature performance is a critical factor to determine its applicability. This investigation focuses on studying the high-temperature properties of SiC ceramics fabricated by using additive manufacturing technology. In this paper, SiC ceramics were prepared by combining selective laser sintering (SLS) with precursor infiltration and pyrolysis (PIP) technique. The microstructure, phase evolution, and failure mechanism after high-temperature tests were explored. SiC ceramic samples tested at room temperature (RT), 800°C, 1200°C, 1400°C, and 1600°C demonstrated bending strengths of 220.0, 226.1, 234.9, 215.5, and 203.7 MPa, respectively. The RT strength of this material can be maintained at 1400°C, but it decreased at 1600°C. The strength retention at 1400°C and 1600°C were 98% and 92%, respectively. The results indicate that the mechanical properties of SiC ceramics prepared using this method have excellent stability. As the temperature increases, the bending strength of the specimens increased slightly and reached the peak value at 1200°C, and dropped to 203.7 MPa at 1600°C. Such an evolution could be mainly due to the crack healing, and the softening of the glassy phase.

@article{chen_boundary-layer_2020,
	title = {Boundary-{Layer} {Thermochemical} {Analysis} {During} {Passive} and {Active} {Oxidation} of {Silicon} {Carbide}},
	volume = {34},
	issn = {0887-8722},
	doi = {10.2514/1.T5864},
	abstract = {Silicon carbide is an ultra-high-temperature ceramic proposed for hypersonic flight applications. However, its use is limited at conditions where oxidation causes aggressive material degradation and a surface temperature “jump” phenomenon. Oxidation is a coupled process, depending on both boundary layer and surface chemistry. An equilibrium surface chemistry model for silicon carbide oxidation is coupled to a nonequilibrium computational fluid dynamics framework, accounting for gas–surface reactions, blowing of oxidation products, and a detailed surface energy balance. Boundary-layer analyses demonstrate a 20–40\% increase in the chemical diffusive heating during passive-to-active transition, and predicted steady-state temperatures agree with experimental measurements within 3\%. Simulated emission spectra show good qualitative agreement with spectra measured in high-enthalpy experiments.},
	number = {3},
	urldate = {2023-10-09},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Chen, Samuel Y. and Boyd, Iain D.},
	year = {2020},
	note = {Publisher: American Institute of Aeronautics and Astronautics
\_eprint: https://doi.org/10.2514/1.T5864},
	pages = {504--515},
}

Silicon carbide is an ultra-high-temperature ceramic proposed for hypersonic flight applications. However, its use is limited at conditions where oxidation causes aggressive material degradation and a surface temperature “jump” phenomenon. Oxidation is a coupled process, depending on both boundary layer and surface chemistry. An equilibrium surface chemistry model for silicon carbide oxidation is coupled to a nonequilibrium computational fluid dynamics framework, accounting for gas–surface reactions, blowing of oxidation products, and a detailed surface energy balance. Boundary-layer analyses demonstrate a 20–40% increase in the chemical diffusive heating during passive-to-active transition, and predicted steady-state temperatures agree with experimental measurements within 3%. Simulated emission spectra show good qualitative agreement with spectra measured in high-enthalpy experiments.

@article{brouwer2020,
	title = {Surrogate-based aeroelastic loads prediction in the presence of shock-induced separation},
	volume = {93},
	issn = {0889-9746},
	doi = {10.1016/j.jfluidstructs.2019.102838},
	abstract = {A surrogate-based modeling strategy is presented for robust and efficient prediction of unsteady aeroelastic loads in the presence of shock-induced separation. Enriched piston theory predictions are extended with a data-driven nonlinear autoregressive with exogenous inputs model to account for hysteresis from the interplay of a dynamically deforming surface with the separation bubble in a shock/boundary layer interaction. The approach is evaluated for prescribed surface motion and shock-induced panel flutter responses, with good agreement observed in each scenario relative to unsteady Reynolds-averaged Navier–Stokes simulations. For the latter, excellent agreement is observed in the prediction of the stability boundary and oscillation frequency. In contrast, the oscillation amplitude conservatively deviates from the Reynolds-averaged Navier–Stokes solution with increasing dynamic pressure. The online computational cost of the extended approach is orders of magnitude less than that required for predictions using an unsteady Reynolds-averaged Navier–Stokes model.},
	language = {en},
	urldate = {2023-08-11},
	journal = {Journal of Fluids and Structures},
	author = {Brouwer, Kirk R. and McNamara, Jack J.},
	month = feb,
	year = {2020},
	keywords = {Kriging, Limit cycle oscillation, NARX model, Panel flutter, Shock impingement, Supersonic, Surrogate models, Two-dimensional},
	pages = {102838},
}

A surrogate-based modeling strategy is presented for robust and efficient prediction of unsteady aeroelastic loads in the presence of shock-induced separation. Enriched piston theory predictions are extended with a data-driven nonlinear autoregressive with exogenous inputs model to account for hysteresis from the interplay of a dynamically deforming surface with the separation bubble in a shock/boundary layer interaction. The approach is evaluated for prescribed surface motion and shock-induced panel flutter responses, with good agreement observed in each scenario relative to unsteady Reynolds-averaged Navier–Stokes simulations. For the latter, excellent agreement is observed in the prediction of the stability boundary and oscillation frequency. In contrast, the oscillation amplitude conservatively deviates from the Reynolds-averaged Navier–Stokes solution with increasing dynamic pressure. The online computational cost of the extended approach is orders of magnitude less than that required for predictions using an unsteady Reynolds-averaged Navier–Stokes model.

@article{huang2020,
	title = {An aerothermoelastic analysis framework with reduced-order modeling applied to composite panels in hypersonic flows},
	volume = {94},
	issn = {0889-9746},
	doi = {10.1016/j.jfluidstructs.2020.102927},
	abstract = {This study describes the enhancement of a computational framework for aerothermoelasticity using novel model order reduction techniques and efficient coupling schemes. First, the fluid solver for hypersonic aerothermodynamics is accelerated using a reduced order model. The flexibility of the reduced order model is enhanced using a novel correction and scaling technique, which accounts for non-uniform temperature distribution, varying flight conditions and geometrical scales using analytical pointwise models. Secondly, based on the reduced order model, a tightly-coupled scheme and linearized stability analysis are developed for fast aerothermoelastic simulation of extended flight time and automatic identification of aerothermoelastic instabilities, respectively. The enhanced framework is accelerated by a factor of 104 so that near-real-time aerothermoelastic simulation is achieved. Finally, using the enhanced framework, the aerothermoelastic response of a generic skin panel is studied emphasizing the effect of flow orientation angle and material orthotropicity on the aerothermoelastic stability boundary. It is found that a combination of flow orientation angle and material orientation can significantly extend the aerothermoelastic stability boundary, i.e. the time elapsed before the onset of structural failure.},
	language = {en},
	urldate = {2023-08-09},
	journal = {Journal of Fluids and Structures},
	author = {Huang, Daning and Friedmann, Peretz P.},
	month = apr,
	year = {2020},
	keywords = {Fluid–thermal-structure interaction, Hypersonic aerothermoelasticity, Linearized stability analysis, Panel flutter, Reduced-order modeling},
	pages = {102927},
}

This study describes the enhancement of a computational framework for aerothermoelasticity using novel model order reduction techniques and efficient coupling schemes. First, the fluid solver for hypersonic aerothermodynamics is accelerated using a reduced order model. The flexibility of the reduced order model is enhanced using a novel correction and scaling technique, which accounts for non-uniform temperature distribution, varying flight conditions and geometrical scales using analytical pointwise models. Secondly, based on the reduced order model, a tightly-coupled scheme and linearized stability analysis are developed for fast aerothermoelastic simulation of extended flight time and automatic identification of aerothermoelastic instabilities, respectively. The enhanced framework is accelerated by a factor of 104 so that near-real-time aerothermoelastic simulation is achieved. Finally, using the enhanced framework, the aerothermoelastic response of a generic skin panel is studied emphasizing the effect of flow orientation angle and material orthotropicity on the aerothermoelastic stability boundary. It is found that a combination of flow orientation angle and material orientation can significantly extend the aerothermoelastic stability boundary, i.e. the time elapsed before the onset of structural failure.

@article{whalen2020,
	title = {Hypersonic {Fluid}–{Structure} {Interactions} in {Compression} {Corner} {Shock}-{Wave}/{Boundary}-{Layer} {Interaction}},
	volume = {58},
	issn = {0001-1452},
	doi = {10.2514/1.J059152},
	abstract = {The fluid–structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 is investigated experimentally for transitional and turbulent incoming boundary layers. Panel deformations are measured using photogrammetry enabled by a new marker-tracking routine, whereas pressure fluctuations are obtained with fast-response piezoresistive pressure transducers. The significance of aerothermal heating is evident in the nonlinear panel response: enhanced static deformations and frequency shifting are consistent with a temperature differential between the panel and its support structure, which induces compressive thermal strain and flexural softening. Time-domain and modal vibratory behavior are correlated to the SWBLI environment, and shear-layer reattachment near antinodes of certain mode shapes is identified as a source of enhanced panel excitation. Comparison with companion rigid-ramp experiments shows evidence of feedback into the downstream flowfield regime.},
	number = {9},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {Whalen, Thomas J. and Schöneich, Antonio Giovanni and Laurence, Stuart J. and Sullivan, Bryson T. and Bodony, Daniel J. and Freydin, Maxim and Dowell, Earl H. and Buck, Gregory M.},
	year = {2020},
	pages = {4090--4105},
}

The fluid–structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 is investigated experimentally for transitional and turbulent incoming boundary layers. Panel deformations are measured using photogrammetry enabled by a new marker-tracking routine, whereas pressure fluctuations are obtained with fast-response piezoresistive pressure transducers. The significance of aerothermal heating is evident in the nonlinear panel response: enhanced static deformations and frequency shifting are consistent with a temperature differential between the panel and its support structure, which induces compressive thermal strain and flexural softening. Time-domain and modal vibratory behavior are correlated to the SWBLI environment, and shear-layer reattachment near antinodes of certain mode shapes is identified as a source of enhanced panel excitation. Comparison with companion rigid-ramp experiments shows evidence of feedback into the downstream flowfield regime.

@inproceedings{sasidharan2020,
	title = {Video: {Pulsating} shock waves at {Mach} 6},
	doi = {10.1103/aps.dfd.2020.gfm.v0015},
	publisher = {American Physical Society (APS)},
	author = {Sasidharan, Vaisakh and Duvvuri, Subrahmanyam},
	month = nov,
	year = {2020},
}

@article{krish2020,
	title = {Ultraviolet {Absorption} {Cross}-{Section} {Measurements} of {Shock}-{Heated} {O}{\textbackslash}textsubscript\{2\} from 2,000-8,400 {K} using a {Tunable} {Laser}},
	volume = {247},
	journal = {Journal of Quantitative Spectroscopy \& Radiative Transfer},
	author = {Krish, Ajay and Streicher, Jesse W and Hanson, Ronald K},
	year = {2020},
}

@inproceedings{chaudhry2020,
	title = {Vehicle-{Scale} {Simulations} of {Hypersonic} {Flows} using the {MMT} {Chemical} {Kinetics} {Model}},
	publisher = {\{AIAA Paper\} 2020-3272},
	author = {Chaudhry, Ross S and Boyd, Iain D and Candler, Graham V},
	month = jun,
	year = {2020},
}

@article{pegmire2020,
	title = {Tennis players at {French} {Open} rattled by sonic boom},
	journal = {Associated Press},
	author = {Pegmire, Jermome},
	year = {2020},
}

@article{macdonald2020,
	title = {State-to-{State} {Master} {Equation} and {Direct} {Molecular} {Simulation} {Study} of {Energy} {Transfer} and {Dissociation} for the {N2}-{N} {System}},
	volume = {124},
	doi = {10.1021/ACS.JPCA.0C04029/ASSET/IMAGES/LARGE/JP0C04029_0013.JPEG},
	abstract = {We present a detailed comparison of two high-fidelity approaches for simulating non-equilibrium chemical processes in gases: The state-to-state master equation (StS-ME) and the direct molecular simulation (DMS) methods. The former is a deterministic method, which relies on the pre-computed kinetic database for the N2-N system based on the NASA Ames ab initio potential energy surface (PES) to describe the evolution of the molecules' internal energy states through a system of master equations. The latter is a stochastic interpretation of molecular dynamics relying exclusively on the same ab initio PES. It directly tracks the microscopic gas state through a particle ensemble undergoing a sequence of collisions. We study a mixture of nitrogen molecules and atoms forced into strong thermochemical non-equilibrium by sudden exposure of rovibrationally cold gas to a high-temperature heat bath. We observe excellent agreement between the DMS and StS-ME predictions for the transfer rates of translational into rotational and vibrational energy, as well as of dissociation rates across a wide range of temperatures. Both methods agree down to the microscopic scale, where they predict the same non-Boltzmann population distributions during quasi-steady-state dissociation. Beyond establishing the equivalence of both methods, this cross-validation helped in reinterpreting the NASA Ames kinetic database and resolve discrepancies observed in prior studies. The close agreement found between the StS-ME and DMS methods, whose sole model inputs are the PESs, lends confidence to their use as benchmark tools for studying high-temperature air chemistry.},
	number = {35},
	journal = {Journal of Physical Chemistry A},
	author = {MacDonald, Robyn L. and Torres, Erik and Schwartzentruber, Thomas E. and Panesi, Marco},
	month = sep,
	year = {2020},
	note = {Publisher: American Chemical Society},
	pages = {6986--7000},
}

We present a detailed comparison of two high-fidelity approaches for simulating non-equilibrium chemical processes in gases: The state-to-state master equation (StS-ME) and the direct molecular simulation (DMS) methods. The former is a deterministic method, which relies on the pre-computed kinetic database for the N2-N system based on the NASA Ames ab initio potential energy surface (PES) to describe the evolution of the molecules' internal energy states through a system of master equations. The latter is a stochastic interpretation of molecular dynamics relying exclusively on the same ab initio PES. It directly tracks the microscopic gas state through a particle ensemble undergoing a sequence of collisions. We study a mixture of nitrogen molecules and atoms forced into strong thermochemical non-equilibrium by sudden exposure of rovibrationally cold gas to a high-temperature heat bath. We observe excellent agreement between the DMS and StS-ME predictions for the transfer rates of translational into rotational and vibrational energy, as well as of dissociation rates across a wide range of temperatures. Both methods agree down to the microscopic scale, where they predict the same non-Boltzmann population distributions during quasi-steady-state dissociation. Beyond establishing the equivalence of both methods, this cross-validation helped in reinterpreting the NASA Ames kinetic database and resolve discrepancies observed in prior studies. The close agreement found between the StS-ME and DMS methods, whose sole model inputs are the PESs, lends confidence to their use as benchmark tools for studying high-temperature air chemistry.

@misc{liza2020,
	address = {AIAA  Tucson Section - Technical Mini Conference},
	type = {Conference {Presentation}},
	title = {Simulation of {Hypersonic} {Flow} {Fields} with {Applications} to {Aero}-{Optics}},
	author = {Liza, Martin E. and Hanquist, Kyle M.},
	year = {2020},
	keywords = {own, presentation},
}

@article{streicher2020,
	title = {Shock-tube measurements of coupled vibration-dissociation time-histories and rate parameters in oxygen and argon mixtures from 5000 {K} to 10 000 {K}},
	volume = {32},
	doi = {10.1063/5.0012426},
	abstract = {Shock-tube experiments were conducted behind reflected shocks using ultraviolet (UV) laser absorption to measure coupled vibration-dissociation (CVDV) time-histories and rate parameters in dilute mixtures of oxygen (O2) and argon (Ar). Experiments probed 2\% and 5\% O2 in Ar mixtures for initial post-reflected-shock conditions from 5000 K to 10 000 K and 0.04 atm to 0.45 atm. A tunable, pulsed UV laser absorption diagnostic measured absorbance time-histories from the fourth, fifth, and sixth vibrational levels of the electronic ground state of O2, and experiments were repeated - with closely matched temperature and pressure conditions - to probe absorbance time-histories corresponding to each vibrational level. The absorbance ratio from two vibrational levels, interpreted via an experimentally validated spectroscopic model, determined vibrational temperature time-histories. In contrast, the absorbance involving a single vibrational level determined vibrational-state-specific number density time-histories. These temperature and state-specific number density time-histories agree reasonably well with state-to-state modeling at low temperatures but deviate significantly at high temperatures. Further analysis of the vibrational temperature and number density time-histories isolated coupling parameters from the Marrone and Treanor CVDV model, including vibrational relaxation time (τ), average vibrational energy loss (ϵ), vibrational coupling factor (Z), and dissociation rate constant (kd). The results for τ and kd are consistent with previous results, exhibit low scatter, and - in the case of vibrational relaxation time - extend measurements to higher temperatures than previous experiments. The results for ϵ and Z overlap some common models, exhibit relatively low scatter, and provide novel experimental data.},
	number = {7},
	journal = {Physics of Fluids},
	author = {Streicher, Jesse W. and Krish, Ajay and Hanson, Ronald K. and Hanquist, Kyle M. and Chaudhry, Ross S. and Boyd, Iain D.},
	year = {2020},
	keywords = {own},
	pages = {1--21},
}

Shock-tube experiments were conducted behind reflected shocks using ultraviolet (UV) laser absorption to measure coupled vibration-dissociation (CVDV) time-histories and rate parameters in dilute mixtures of oxygen (O2) and argon (Ar). Experiments probed 2% and 5% O2 in Ar mixtures for initial post-reflected-shock conditions from 5000 K to 10 000 K and 0.04 atm to 0.45 atm. A tunable, pulsed UV laser absorption diagnostic measured absorbance time-histories from the fourth, fifth, and sixth vibrational levels of the electronic ground state of O2, and experiments were repeated - with closely matched temperature and pressure conditions - to probe absorbance time-histories corresponding to each vibrational level. The absorbance ratio from two vibrational levels, interpreted via an experimentally validated spectroscopic model, determined vibrational temperature time-histories. In contrast, the absorbance involving a single vibrational level determined vibrational-state-specific number density time-histories. These temperature and state-specific number density time-histories agree reasonably well with state-to-state modeling at low temperatures but deviate significantly at high temperatures. Further analysis of the vibrational temperature and number density time-histories isolated coupling parameters from the Marrone and Treanor CVDV model, including vibrational relaxation time (τ), average vibrational energy loss (ϵ), vibrational coupling factor (Z), and dissociation rate constant (kd). The results for τ and kd are consistent with previous results, exhibit low scatter, and - in the case of vibrational relaxation time - extend measurements to higher temperatures than previous experiments. The results for ϵ and Z overlap some common models, exhibit relatively low scatter, and provide novel experimental data.

@misc{loseille2020,
	title = {{PyAMG}},
	url = {https://pyamg.saclay.inria.fr},
	author = {Loseille, A. and Menier, V.},
	year = {2020},
}

@inproceedings{flora2020,
	address = {Orlando, FL},
	title = {On characterizing nonequilibrium at the shock-front in shock tube experiments with pure oxygen},
	publisher = {\{AIAA Paper\} 2020-0621},
	author = {Flora, G and Karimzadeh, F and Yamada, T and Grinstead, K D and Kahandawala, M S P and Valentini, P and Grover, M S and Adamovich, Igor V and Carter, C D and Josyula, E},
	month = jan,
	year = {2020},
}

@inproceedings{garbacz2020,
	title = {Numerical {Study} of {Shock} {Interference} {Patterns} for {Gas} {Flows} with {Thermal} {Nonequilibrium} and {Finite}-{Rate} {Chemistry}},
	doi = {10.2514/6.2020-1805},
	publisher = {\{AIAA Paper\} 2020-1805},
	author = {Garbacz, Catrina and Fossati, Marco and Maier, Walter T and Alanso, Juan J and Scoggins, James B and Economon, Thomas D and Magin, Thierry E},
	year = {2020},
}

@article{linstrom2020,
	title = {{NIST} {Chemistry} {WebBook}, {NIST} {Standard} {Reference} {Database} {Number} 69},
	url = {https://doi.org/10.18434/T4D303},
	editor = {Linstrom, P J and Mallard, W G},
	year = {2020},
	note = {Publisher: National Institute of Standards and Technology,},
}

@misc{hanquist2020,
	address = {Mechanical, Aerospace, and Biomedical Engineering Department, University of Tennessee-Knoxville},
	type = {Invited {Seminar}},
	title = {Need for {Speed}: {Hypersonic} {Flight}},
	author = {Hanquist, Kyle M.},
	year = {2020},
	keywords = {invited, own},
}

@article{scoggins2020,
	title = {Mutation++: {MUlticomponent} {Thermodynamic} {And} {Transport} properties for {IONized} gases in {C}++},
	volume = {12},
	issn = {23527110},
	doi = {10.1016/j.softx.2020.100575},
	abstract = {The Mutation++ library provides accurate and efficient computation of physicochemical properties associated with partially ionized gases in various degrees of thermal nonequilibrium. With v1.0.0, users can compute thermodynamic and transport properties, multiphase linearly-constrained equilibria, chemical production rates, energy transfer rates, and gas-surface interactions. The framework is based on an object-oriented design in C++, allowing users to plug-and-play various models, algorithms, and data as necessary. Mutation++ is available open-source under the GNU Lesser General Public License v3.0.},
	urldate = {2021-02-23},
	journal = {SoftwareX},
	author = {Scoggins, James B. and Leroy, Vincent and Bellas-Chatzigeorgis, Georgios and Dias, Bruno and Magin, Thierry E.},
	month = jul,
	year = {2020},
	note = {arXiv: 2002.01783
Publisher: Elsevier B.V.},
	keywords = {Gas-surface interaction, Multiphase equilibrium, Partially ionized gases, Thermochemical nonequilibrium},
	pages = {100575},
}

The Mutation++ library provides accurate and efficient computation of physicochemical properties associated with partially ionized gases in various degrees of thermal nonequilibrium. With v1.0.0, users can compute thermodynamic and transport properties, multiphase linearly-constrained equilibria, chemical production rates, energy transfer rates, and gas-surface interactions. The framework is based on an object-oriented design in C++, allowing users to plug-and-play various models, algorithms, and data as necessary. Mutation++ is available open-source under the GNU Lesser General Public License v3.0.

@article{scoggins2020a,
	title = {Mutation++: {MUlticomponent} {Thermodynamic} {And} {Transport} properties for {IONized} gases in {C}++},
	volume = {12},
	doi = {10.1016/j.softx.2020.100575},
	abstract = {The Mutation++ library provides accurate and efficient computation of physicochemical properties associated with partially ionized gases in various degrees of thermal nonequilibrium. With v1.0.0, users can compute thermodynamic and transport properties, multiphase linearly-constrained equilibria, chemical production rates, energy transfer rates, and gas-surface interactions. The framework is based on an object-oriented design in C++, allowing users to plug-and-play various models, algorithms, and data as necessary. Mutation++ is available open-source under the GNU Lesser General Public License v3.0.},
	journal = {SoftwareX},
	author = {Scoggins, James B. and Leroy, Vincent and Bellas-Chatzigeorgis, Georgios and Dias, Bruno and Magin, Thierry E.},
	month = jul,
	year = {2020},
	note = {Publisher: Elsevier B.V.},
	keywords = {Gas-surface interaction, Multiphase equilibrium, Partially ionized gases, Thermochemical nonequilibrium},
	pages = {100575--100575},
}

The Mutation++ library provides accurate and efficient computation of physicochemical properties associated with partially ionized gases in various degrees of thermal nonequilibrium. With v1.0.0, users can compute thermodynamic and transport properties, multiphase linearly-constrained equilibria, chemical production rates, energy transfer rates, and gas-surface interactions. The framework is based on an object-oriented design in C++, allowing users to plug-and-play various models, algorithms, and data as necessary. Mutation++ is available open-source under the GNU Lesser General Public License v3.0.

@article{scoggins2020b,
	title = {Mutation\${\textasciicircum}\{++\}\$: {MUlticomponent} {Thermodynamic} {And} {Transport} properties for {IONized} gases in {C}\$++\$},
	volume = {12},
	doi = {10.1016/j.softx.2020.100575},
	journal = {SoftwareX},
	author = {Scoggins, James B and Leroy, Vincent and Bellas-Chatzigeorgis, Georgios and Dias, Bruno and Magin, Thierry E},
	year = {2020},
}

@inproceedings{hanquist2020i,
	title = {Modeling {High}-{Temperature} {Flow} {Field} {Effects} {Relevant} to {Fluid}-{Thermal}-{Structural} {Interactions}},
	booktitle = {Joint {Meeting} of the {Combustion}, {Airbreathing} {Propulsion}, {Exhaust} {Plume} and {Signatures}, and {Energetic} {Systems} {Hazards} subcommittees, and {Programmatic} and {Industrial} {Base} meeting},
	publisher = {JANNAF},
	author = {Hanquist, Kyle M. and Düzel, Ümran and Liza, Martin E. and Sadagopan, Aravinth and Huang, Daning},
	year = {2020},
	keywords = {own},
}

@article{tropina2020a,
	title = {Influence of vibrational non-equilibrium on the polarizability and refraction index in air: computational study},
	volume = {53},
	issn = {0022-3727, 1361-6463},
	shorttitle = {Influence of vibrational non-equilibrium on the polarizability and refraction index in air},
	url = {https://iopscience.iop.org/article/10.1088/1361-6463/ab5bb2},
	doi = {10.1088/1361-6463/ab5bb2},
	abstract = {Knowledge of optical effects accompanying hypersonic flight conditions is of critical importance to ensure reliable operation of on-board optical instrumentation. This paper presents results of calculations of scalar polarizability dependence on vibrational nonequilibrium in molecular nitrogen and oxygen. The non-equilibrium effects are evaluated on the basis of a semi-classical model for the molecular polarizability. It is shown that, depending on the vibrational and translational populations, changes in the scalar polarizability in excess of normal density and temperature scaling can be around 1\%–5\% at moderate gas temperatures and around 10\% at high temperatures. The model was applied to predict the polarizability for non-equilibrium states in a nitrogen plasma formed by a single nanosecond pulse with different rise times.},
	language = {en},
	number = {10},
	urldate = {2023-05-04},
	journal = {Journal of Physics D: Applied Physics},
	author = {Tropina, Albina A and Wu, Yue and Limbach, Christopher M and Miles, Richard B},
	month = mar,
	year = {2020},
	pages = {105201},
}

Knowledge of optical effects accompanying hypersonic flight conditions is of critical importance to ensure reliable operation of on-board optical instrumentation. This paper presents results of calculations of scalar polarizability dependence on vibrational nonequilibrium in molecular nitrogen and oxygen. The non-equilibrium effects are evaluated on the basis of a semi-classical model for the molecular polarizability. It is shown that, depending on the vibrational and translational populations, changes in the scalar polarizability in excess of normal density and temperature scaling can be around 1%–5% at moderate gas temperatures and around 10% at high temperatures. The model was applied to predict the polarizability for non-equilibrium states in a nitrogen plasma formed by a single nanosecond pulse with different rise times.

@inproceedings{chaudhry2020a,
	address = {Orlando, FL},
	title = {Implementation of a {Chemical} {Kinetics} {Model} for {Hypersonic} {Flows} in {Air} for {High}-{Performance} {CFD}},
	publisher = {\{AIAA Paper\} 2020-2191},
	author = {Chaudhry, Ross S and Boyd, Iain D and Torres, Erik and Schwartzentruber, Thomas E and Candler, Graham},
	month = jan,
	year = {2020},
}

@inproceedings{morin2020,
	address = {Orlando, FL},
	title = {Inductively {Coupled} {Facility} {Qualification} for {Electron} {Transpiration} {Cooling} {Investigations}},
	publisher = {\{AIAA Paper\} 2020-0921},
	author = {Morin, Andrew J and Osborn, Rebecca and Schindler, Jeff C and Jagun, Precious and Fletcher, Douglas G and Meyers, Jason M},
	month = jan,
	year = {2020},
	keywords = {etc},
}

@inproceedings{vogiatzis2020,
	address = {Orlando, FL},
	title = {{HyperCode}: {A} framework for high-order accurate turbulent non-equilibrium hypersonic flow simulations},
	publisher = {AIAA 2020-2192},
	author = {Vogiatzis, Konstantinos and Munafò, Alessandro and Panesi, Marco and Vedula, Prakash and Josyula, Eswar},
	month = jan,
	year = {2020},
}

@inproceedings{parent2020b,
	title = {Fully-{Coupled} {Simulation} of {Plasma} {Discharges}, {Turbulence}, and {Combustion} in a {Scramjet} {Combustor}},
	doi = {10.2514/6.2020-3230},
	abstract = {Simulating plasma-assisted combustion represents a considerable challenge due to the large discrepancy of the time scales involved. While the turbulent eddy time scales are of the order of microseconds, the plasma sheath time scales are 3-4 orders of magnitude lower. Contrarily to the chemical reactions, the stiffness of the plasma equations can not be relieved simply by using an implicit integration strategy, thus leading to excessive computational effort even for the simplest cases. Recently, it was shown that this hurdle can be overcome by recasting the plasma driftdiffusion transport equations such that the potential is not obtained from Gauss’s law directly but rather from Ohm’s law. Such a recast is performed while still ensuring that Gauss’s law is satisfied and thus does not modify the physics of the drift-diffusion model in any way. In this paper, we use this novel approach to integrate, for the first time, a plasma discharge in fully coupled form with the turbulent hydrogen/air mixing layer and combustion process taking place in the combustor of a scramjet flying at Mach 11. The chemical model includes electrons, 7 different types of ions, 11 neutral species and 79 reactions. Results indicate that more than 5 discharges need to be performed before achieving a self-repeating pattern due to the strong coupling between the flow, combustion, and plasma. Further, the plasma-assisted flame anchoring is seen to create a recirculation region of significant size within the turbulent boundary layer which affects skin friction and heat loads considerably.},
	booktitle = {{AIAA} {Aviation} and {Aeronautics} {Forum} and {Exposition}},
	publisher = {AIAA Paper 2020-3230},
	author = {Parent, Bernard and Omprakas, Ajjay and Hanquist, Kyle M.},
	year = {2020},
	keywords = {own},
}

Simulating plasma-assisted combustion represents a considerable challenge due to the large discrepancy of the time scales involved. While the turbulent eddy time scales are of the order of microseconds, the plasma sheath time scales are 3-4 orders of magnitude lower. Contrarily to the chemical reactions, the stiffness of the plasma equations can not be relieved simply by using an implicit integration strategy, thus leading to excessive computational effort even for the simplest cases. Recently, it was shown that this hurdle can be overcome by recasting the plasma driftdiffusion transport equations such that the potential is not obtained from Gauss’s law directly but rather from Ohm’s law. Such a recast is performed while still ensuring that Gauss’s law is satisfied and thus does not modify the physics of the drift-diffusion model in any way. In this paper, we use this novel approach to integrate, for the first time, a plasma discharge in fully coupled form with the turbulent hydrogen/air mixing layer and combustion process taking place in the combustor of a scramjet flying at Mach 11. The chemical model includes electrons, 7 different types of ions, 11 neutral species and 79 reactions. Results indicate that more than 5 discharges need to be performed before achieving a self-repeating pattern due to the strong coupling between the flow, combustion, and plasma. Further, the plasma-assisted flame anchoring is seen to create a recirculation region of significant size within the turbulent boundary layer which affects skin friction and heat loads considerably.

@techreport{fields2020,
	title = {Fact {Sheet} - {Supersonic} {Flight}},
	url = {https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=22754},
	author = {Fields, NIa},
	year = {2020},
}

@article{bellas-chatzigeorgis2020,
	title = {Energy accommodation coefficient calculation methodology using state-to-state catalysis applied to hypersonic flows},
	volume = {58},
	doi = {10.2514/1.J058543},
	abstract = {The interplay of a gas–surface interaction and thermal nonequilibrium is still an open problem in aerothermodynamics. In the case of reusable thermal protection systems, it is unclear how much of the recombination energy is stored internally in the molecules produced by surface catalytic reactions, potentially leading to nonequilibrium between their translational and internal energy modes. A methodology is developed to calculate the energy accommodation coefficient using a rovibrational state-to-state chemical mechanism for a nitrogen mixture coupled with a generalized form of the catalytic recombination coefficient. The flow around a spherical body is simulated in hypersonic conditions, allowing study of the amount of energy deposited on the surface and stored in the recombining molecules. Internal energy quenching into translational energy is found, which is a phenomenon also observed experimentally, keeping the total energy transferred to the surface overall constant. The methodology developed for the application of a state-to-state model in the computational fluid dynamics framework coupled with catalysis is generic and applicable to a variety of other similar mechanisms.},
	number = {1},
	journal = {AIAA Journal},
	author = {Bellas-Chatzigeorgis, Georgios and Magin, Thierry E. and Barbante, Paolo F.},
	month = nov,
	year = {2020},
	note = {Publisher: AIAA International},
	keywords = {Aerothermodynamics, Chemical Equilibrium, Computational Fluid Dynamics, Freestream Conditions, Heterogeneous Catalysis, Hypersonic Flows, Quenching, Thermal Nonequilibrium, Thermal Protection System, Vibrational Energy},
	pages = {278--290},
}

The interplay of a gas–surface interaction and thermal nonequilibrium is still an open problem in aerothermodynamics. In the case of reusable thermal protection systems, it is unclear how much of the recombination energy is stored internally in the molecules produced by surface catalytic reactions, potentially leading to nonequilibrium between their translational and internal energy modes. A methodology is developed to calculate the energy accommodation coefficient using a rovibrational state-to-state chemical mechanism for a nitrogen mixture coupled with a generalized form of the catalytic recombination coefficient. The flow around a spherical body is simulated in hypersonic conditions, allowing study of the amount of energy deposited on the surface and stored in the recombining molecules. Internal energy quenching into translational energy is found, which is a phenomenon also observed experimentally, keeping the total energy transferred to the surface overall constant. The methodology developed for the application of a state-to-state model in the computational fluid dynamics framework coupled with catalysis is generic and applicable to a variety of other similar mechanisms.

@techreport{hanquist2020g,
	title = {Detailed {Investigation} of {Nonequilibrium} {Effects} on {Aero}-{Optics} in {Hypersonic} {Flows}},
	url = {https://chanl.arizona.edu/afrl-final-report-2020},
	institution = {University of Arizona - Air Force Research Laboratory},
	author = {Hanquist, Kyle M.},
	year = {2020},
}

@inproceedings{hanquist2020h,
	title = {Detailed {Thermochemical} {Modeling} of {O}$_{\textrm{2}}$-{Ar} in {Reflected} {Shock} {Tube} {Flows}},
	doi = {10.2514/6.2020-3275},
	abstract = {Simulation results are presented of a set of vibrational nonequilibrium models with a range of fidelity and are compared to experimental data for several post-normal reflected shock test cases of O2-Ar mixtures. Three different modeling approaches with a range of fidelity are used to determine the vibrational nonequilibrium of the post-normal shock flows. The twotemperature (2T) model is the widely used approach for hypersonic analysis and is presented as the computationally efficient, lower fidelity modeling approach in this work. In contrast, the full state-to-state (STS) model, a master equation approach for each vibrational state, is presented as the higher fidelity modeling approach. Both approaches have several available methods for obtaining rate data that are investigated. The STS approach uses rate data from the forced harmonic oscillator (FHO) approach and quasi-classical trajectory analysis (QCT) for the O2-Ar, O2-O, and O2-O2 systems. The simulated vibrational temperatures and state-specific vibrational level concentrations are compared to experimental measurements. The experimental measurements have a low level of uncertainty and allow for insight into the performance of the nonequilibrium modeling. A rate sensitivity study is also completed that shows how sensitive the results are to certain rates at each experimental condition.},
	booktitle = {{AIAA} {Aviation} and {Aeronautics} {Forum} and {Exposition}},
	publisher = {AIAA Paper 2020-3275},
	author = {Hanquist, Kyle M. and Chaudhry, Ross S. and Boyd, Iain D. and Streicher, Jesse W. and Krish, Ajay and Hanson, Ronald K.},
	year = {2020},
	keywords = {own},
}

Simulation results are presented of a set of vibrational nonequilibrium models with a range of fidelity and are compared to experimental data for several post-normal reflected shock test cases of O2-Ar mixtures. Three different modeling approaches with a range of fidelity are used to determine the vibrational nonequilibrium of the post-normal shock flows. The twotemperature (2T) model is the widely used approach for hypersonic analysis and is presented as the computationally efficient, lower fidelity modeling approach in this work. In contrast, the full state-to-state (STS) model, a master equation approach for each vibrational state, is presented as the higher fidelity modeling approach. Both approaches have several available methods for obtaining rate data that are investigated. The STS approach uses rate data from the forced harmonic oscillator (FHO) approach and quasi-classical trajectory analysis (QCT) for the O2-Ar, O2-O, and O2-O2 systems. The simulated vibrational temperatures and state-specific vibrational level concentrations are compared to experimental measurements. The experimental measurements have a low level of uncertainty and allow for insight into the performance of the nonequilibrium modeling. A rate sensitivity study is also completed that shows how sensitive the results are to certain rates at each experimental condition.

@techreport{hanquist2020f,
	title = {Detailed {Investigation} of {Nonequilibrium} {Effects} on {Aero}-{Optics} in {Hypersonic} {Flows}},
	url = {https://chanl.arizona.edu/afrl-final-report-2020},
	author = {Hanquist, Kyle M.},
	year = {2020},
}

@article{gardner2020,
	title = {Covid-19 has {Forced} {Higher} {Ed} to {Pivot} to {Online} {Learning}. {Here} are 7 {Takeaways} so {Far}.},
	journal = {The Chronicle of Higher Education},
	author = {Gardner, L.},
	year = {2020},
}

@techreport{hanquist2020c,
	title = {Detailed {Investigation} of {Nonequilibrium} {Effects} on {Aero}-{Optics} in {Hypersonic} {Flows}},
	author = {Hanquist, Kyle M and Liza, Martin E},
	month = sep,
	year = {2020},
}

@article{brune2020,
	title = {Calibration probe uncertainty and validation for the hypersonic material environmental test system},
	volume = {34},
	doi = {10.2514/1.T5839},
	abstract = {This paper presents an uncertainty analysis of the stagnation-point calibration probe surface predictions for conditions that span the performance envelope of the Hypersonic Materials Environmental Test System facility located at NASA Langley Research Center. A second-order stochastic expansion was constructed over 47 uncertain parameters to evaluate the sensitivities, identify the most significant uncertain variables, and quantify the uncertainty in the stagnation-point heat flux and pressure predictions of the calibration probe for low- and high-enthalpy test conditions. A sensitivity analysis showed that measurement bias uncertainty is the most significant contributor to the stagnation-point pressure and heat flux variance for the low-enthalpy condition. For the high-enthalpy condition, a paradigm shift in sensitivities revealed the computational fluid dynamics model input uncertainty as the main contributor. A comparison between the prediction and measurement of the stagnation-point conditions under uncertainty showed that there was evidence of statistical disagreement. A validation metric was proposed and applied to the prediction uncertainty to account for the statistical disagreement when compared with the possible stagnation-point heat flux and pressure measurements.},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Brune, Andrew J. and West, Thomas K. and Whit, Laura M.},
	month = jan,
	year = {2020},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {CFD Simulation, Collocation Method, Cumulative Distribution Function, Enthalpy, Heat Flux, NASA Langley Research Center, Sensitivity Analysis, Slug Calorimeters, Stagnation Pressure, Thermal Protection System},
	pages = {404--420},
}

This paper presents an uncertainty analysis of the stagnation-point calibration probe surface predictions for conditions that span the performance envelope of the Hypersonic Materials Environmental Test System facility located at NASA Langley Research Center. A second-order stochastic expansion was constructed over 47 uncertain parameters to evaluate the sensitivities, identify the most significant uncertain variables, and quantify the uncertainty in the stagnation-point heat flux and pressure predictions of the calibration probe for low- and high-enthalpy test conditions. A sensitivity analysis showed that measurement bias uncertainty is the most significant contributor to the stagnation-point pressure and heat flux variance for the low-enthalpy condition. For the high-enthalpy condition, a paradigm shift in sensitivities revealed the computational fluid dynamics model input uncertainty as the main contributor. A comparison between the prediction and measurement of the stagnation-point conditions under uncertainty showed that there was evidence of statistical disagreement. A validation metric was proposed and applied to the prediction uncertainty to account for the statistical disagreement when compared with the possible stagnation-point heat flux and pressure measurements.

@article{holloway2020a,
	title = {Assessment of {Thermochemistry} {Modeling} for {Hypersonic} {Flow} over a {Double} {Cone}},
	volume = {34},
	doi = {10.2514/1.T5792},
	abstract = {The influence of different assumptions for thermochemistry modeling in hypersonic flow over a double-cone geometry is investigated. A computational fluid dynamics analysis is used to study the double cone in three different thermochemical cases, nonequilibrium flow, equilibrium flow, and frozen flow, for four different mixtures of nitrogen and oxygen. Specific areas of interest include the thermochemistry model effects on the flowfield and surface properties. The resulting aerodynamic loads are compared with experiments and indicate that thermochemistry modeling assumptions play a significant role in determining surface properties. It is also shown that heat loading is more sensitive to thermochemical modeling than drag and suggests that an accurate measurement of surface heat transfer is of particular interest. Careful analysis also reveals that high-enthalpy and pure oxygen flows are particularly sensitive to the thermochemistry model assumed. Consistent overprediction or underprediction of pressure drag and heat load by all three chemistry models for most of the cases considered indicates a fundamental difference between the actual experiments and the simulations, thus limiting the usefulness of the double-cone data for validation of thermochemistry models.},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Holloway, Michael E. and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2020},
	keywords = {own},
	pages = {538--547},
}

The influence of different assumptions for thermochemistry modeling in hypersonic flow over a double-cone geometry is investigated. A computational fluid dynamics analysis is used to study the double cone in three different thermochemical cases, nonequilibrium flow, equilibrium flow, and frozen flow, for four different mixtures of nitrogen and oxygen. Specific areas of interest include the thermochemistry model effects on the flowfield and surface properties. The resulting aerodynamic loads are compared with experiments and indicate that thermochemistry modeling assumptions play a significant role in determining surface properties. It is also shown that heat loading is more sensitive to thermochemical modeling than drag and suggests that an accurate measurement of surface heat transfer is of particular interest. Careful analysis also reveals that high-enthalpy and pure oxygen flows are particularly sensitive to the thermochemistry model assumed. Consistent overprediction or underprediction of pressure drag and heat load by all three chemistry models for most of the cases considered indicates a fundamental difference between the actual experiments and the simulations, thus limiting the usefulness of the double-cone data for validation of thermochemistry models.

@article{venturi2020,
	title = {Bayesian {Machine} {Learning} {Approach} to the {Quantification} of {Uncertainties} on {Ab} {Initio} {Potential} {Energy} {Surfaces}},
	volume = {124},
	url = {https://pubs.acs.org/doi/full/10.1021/acs.jpca.0c02395},
	doi = {10.1021/ACS.JPCA.0C02395/ASSET/IMAGES/LARGE/JP0C02395_0012.JPEG},
	abstract = {This work introduces a novel methodology for the quantification of uncertainties associated with potential energy surfaces (PESs) computed from first-principles quantum mechanical calculations. The methodology relies on Bayesian inference and machine learning techniques to construct a stochastic PES and to express the inadequacies associated with the ab initio data points and their fit. By combining high fidelity calculations and reduced-order modeling, the resulting stochastic surface is efficiently forward propagated via quasi-classical trajectory and master equation calculations. In this way, the PES contribution to the uncertainty on predefined quantities of interest (QoIs) is explicitly determined. This study is done at both microscopic (e.g., rovibrational-specific rate coefficients) and macroscopic (e.g., thermal and chemical relaxation properties) levels. A correlation analysis is finally applied to identify the PES regions that require further refinement, based on their effects on the QoI reliability. The methodology is applied to the study of singlet (11A′) and quintet (25A′) PESs describing the interaction between O2 molecules and O atoms in their ground electronic state. The investigation of the singlet surface reveals a negligible uncertainty on the kinetic properties and relaxation times, which are found to be in excellent agreement with the ones previously published in the literature. On the other hand, the methodology demonstrated significant uncertainty on the quintet surface, due to inaccuracies in the description of the exchange barrier and the repulsive wall. When forward propagated, this uncertainty is responsible for the variability of 1 order of magnitude in the vibrational relaxation time and of factor four in the exchange reaction rate coefficient, both at 2500 K.},
	number = {25},
	journal = {Journal of Physical Chemistry A},
	author = {Venturi, S. and Jaffe, R. L. and Panesi, M.},
	month = jun,
	year = {2020},
	note = {Publisher: American Chemical Society},
	pages = {5129--5146},
}

This work introduces a novel methodology for the quantification of uncertainties associated with potential energy surfaces (PESs) computed from first-principles quantum mechanical calculations. The methodology relies on Bayesian inference and machine learning techniques to construct a stochastic PES and to express the inadequacies associated with the ab initio data points and their fit. By combining high fidelity calculations and reduced-order modeling, the resulting stochastic surface is efficiently forward propagated via quasi-classical trajectory and master equation calculations. In this way, the PES contribution to the uncertainty on predefined quantities of interest (QoIs) is explicitly determined. This study is done at both microscopic (e.g., rovibrational-specific rate coefficients) and macroscopic (e.g., thermal and chemical relaxation properties) levels. A correlation analysis is finally applied to identify the PES regions that require further refinement, based on their effects on the QoI reliability. The methodology is applied to the study of singlet (11A′) and quintet (25A′) PESs describing the interaction between O2 molecules and O atoms in their ground electronic state. The investigation of the singlet surface reveals a negligible uncertainty on the kinetic properties and relaxation times, which are found to be in excellent agreement with the ones previously published in the literature. On the other hand, the methodology demonstrated significant uncertainty on the quintet surface, due to inaccuracies in the description of the exchange barrier and the repulsive wall. When forward propagated, this uncertainty is responsible for the variability of 1 order of magnitude in the vibrational relaxation time and of factor four in the exchange reaction rate coefficient, both at 2500 K.

@inproceedings{gupta2020,
	address = {Orlando, FL},
	title = {Analytical {Approach} for {Aero}-{Optical} and {Atmospheric} {Effects} in {Supersonic} {Flow} {Fields}},
	publisher = {AIAA 2020-0684},
	author = {Gupta, Anubhav and Argrow, Brian},
	month = jan,
	year = {2020},
}

@techreport{vasile2020,
	address = {ARL-TR-9019},
	title = {Aerodynamic {Dataset} {Generation} of a {Long}-{Range} {Projectile}},
	author = {Vasile, Joseph D and Bryson, Joshua T and Sahu, Jubaraj and Paul, Justin L and Gruenwald, Benjamin C},
	year = {2020},
	keywords = {ARL-TR-9019, US Army Combat Capabilities Development Command (CCDC) Army Research Laboratory (ARL), aerodynamic characterization, airframe design, computational fluid dynamics, lift-to-drag, long-range guided projectiles},
}

@phdthesis{huang2019a,
	address = {Ann Arbor},
	title = {Development of a {Hypersonic} {Aerothermoelastic} {Framework} and {Its} {Application} to {Flutter} and {Aerothermoelastic} {Scaling} of {Skin} {Panels}},
	url = {https://hdl.handle.net/2027.42/151461},
	school = {University of Michigan},
	author = {Huang, Daning},
	year = {2019},
}

@inproceedings{ratnayake2019,
	address = {Dallas, Texas},
	title = {Computational {Fluid} {Dynamics} {Methods} used in the {Development} of the {Space} {Launch} {System} {Liftoff} and {Transition} {Lineloads} {Databases}},
	publisher = {AIAA},
	author = {Ratnayake, Nalin and Krist, Steven and Ghaffari, Farhad and Deere, Karen},
	month = jun,
	year = {2019},
}

@inproceedings{chaudhry2019,
	address = {San Diego, CA},
	title = {Statistical {Analyses} of {Quasiclassical} {Trajectory} {Data} for {Air} {Dissociation}},
	doi = {10.2514/6.2019-0789},
	publisher = {AIAA Paper 2019-0789},
	author = {Chaudhry, Ross S and Candler, Graham V},
	month = jan,
	year = {2019},
}

@article{mortari2019,
	title = {High accuracy least-squares solutions of nonlinear differential equations},
	volume = {352},
	issn = {0377-0427},
	url = {https://www.sciencedirect.com/science/article/pii/S0377042718307325},
	doi = {10.1016/j.cam.2018.12.007},
	abstract = {This study shows how to obtain least-squares solutions to initial and boundary value problems of ordinary nonlinear differential equations. The proposed method begins using an approximate solution obtained by any existing integrator. Then, a least-squares fitting of this approximate solution is obtained using a constrained expression, derived from Theory of Connections. In this expression, the differential equation constraints are embedded and are always satisfied. The resulting constrained expression is then used as an initial guess in a Newton iterative process that increases the solution accuracy to machine error level in no more than two iterations for most of the problems considered. An analysis of speed and accuracy has been conducted for this method using two nonlinear differential equations. For non-smooth solutions or for long integration times, a piecewise approach is proposed. The highly accurate value estimated at the final time is then used as the new initial guess for the next time range, and this process is repeated for subsequent time ranges. This approach has been applied and validated solving the Duffing oscillator obtaining a final solution error on the order of 10−12. To complete the study, a final numerical test is provided for a boundary value problem with a known solution.},
	urldate = {2024-04-24},
	journal = {Journal of Computational and Applied Mathematics},
	author = {Mortari, Daniele and Johnston, Hunter and Smith, Lidia},
	month = may,
	year = {2019},
	keywords = {Embedded linear constraints, Interpolation, Linear least-squares},
	pages = {293--307},
}

This study shows how to obtain least-squares solutions to initial and boundary value problems of ordinary nonlinear differential equations. The proposed method begins using an approximate solution obtained by any existing integrator. Then, a least-squares fitting of this approximate solution is obtained using a constrained expression, derived from Theory of Connections. In this expression, the differential equation constraints are embedded and are always satisfied. The resulting constrained expression is then used as an initial guess in a Newton iterative process that increases the solution accuracy to machine error level in no more than two iterations for most of the problems considered. An analysis of speed and accuracy has been conducted for this method using two nonlinear differential equations. For non-smooth solutions or for long integration times, a piecewise approach is proposed. The highly accurate value estimated at the final time is then used as the new initial guess for the next time range, and this process is repeated for subsequent time ranges. This approach has been applied and validated solving the Duffing oscillator obtaining a final solution error on the order of 10−12. To complete the study, a final numerical test is provided for a boundary value problem with a known solution.

@article{linke2019,
	title = {Challenges for plasma-facing components in nuclear fusion},
	volume = {4},
	issn = {2468-2047},
	doi = {10.1063/1.5090100},
	abstract = {The interaction processes between the burning plasma and the first wall in a fusion reactor are diverse: the first wall will be exposed to extreme thermal loads of up to several tens of megawatts per square meter during quasistationary operation, combined with repeated intense thermal shocks (with energy densities of up to several megajoules per square meter and pulse durations on a millisecond time scale). In addition to these thermal loads, the wall will be subjected to bombardment by plasma ions and neutral particles (D, T, and He) and by energetic neutrons with energies up to 14 MeV. Hopefully, ITER will not only demonstrate that thermonuclear fusion of deuterium and tritium is feasible in magnetic confinement regimes; it will also act as a first test device for plasma-facing materials (PFMs) and plasma-facing components (PFCs) under realistic synergistic loading scenarios that cover all the above-mentioned load types. In the absence of an integrated test device, material tests are being performed primarily in specialized facilities that concentrate only on the most essential material properties. New multipurpose test facilities are now available that can also focus on more complex loading scenarios and thus help to minimize the risk of an unexpected material or component failure. Thermonuclear fusion—both with magnetic and with inertial confinement—is making great progress, and the goal of scientific break-even will be reached soon. However, to achieve that end, significant technical problems, particularly in the field of high-temperature and radiation-resistant materials, must be solved. With ITER, the first nuclear reactor that burns a deuterium–tritium plasma with a fusion power gain Q ≥ 10 will start operation in the next decade. To guarantee safe operation of this rather sophisticated fusion device, new PFMs and PFCs that are qualified to withstand the harsh environments in such a tokamak reactor have been developed and are now entering the manufacturing stage.},
	number = {5},
	urldate = {2024-04-24},
	journal = {Matter and Radiation at Extremes},
	author = {Linke, Jochen and Du, Juan and Loewenhoff, Thorsten and Pintsuk, Gerald and Spilker, Benjamin and Steudel, Isabel and Wirtz, Marius},
	month = aug,
	year = {2019},
	pages = {056201},
}

The interaction processes between the burning plasma and the first wall in a fusion reactor are diverse: the first wall will be exposed to extreme thermal loads of up to several tens of megawatts per square meter during quasistationary operation, combined with repeated intense thermal shocks (with energy densities of up to several megajoules per square meter and pulse durations on a millisecond time scale). In addition to these thermal loads, the wall will be subjected to bombardment by plasma ions and neutral particles (D, T, and He) and by energetic neutrons with energies up to 14 MeV. Hopefully, ITER will not only demonstrate that thermonuclear fusion of deuterium and tritium is feasible in magnetic confinement regimes; it will also act as a first test device for plasma-facing materials (PFMs) and plasma-facing components (PFCs) under realistic synergistic loading scenarios that cover all the above-mentioned load types. In the absence of an integrated test device, material tests are being performed primarily in specialized facilities that concentrate only on the most essential material properties. New multipurpose test facilities are now available that can also focus on more complex loading scenarios and thus help to minimize the risk of an unexpected material or component failure. Thermonuclear fusion—both with magnetic and with inertial confinement—is making great progress, and the goal of scientific break-even will be reached soon. However, to achieve that end, significant technical problems, particularly in the field of high-temperature and radiation-resistant materials, must be solved. With ITER, the first nuclear reactor that burns a deuterium–tritium plasma with a fusion power gain Q ≥ 10 will start operation in the next decade. To guarantee safe operation of this rather sophisticated fusion device, new PFMs and PFCs that are qualified to withstand the harsh environments in such a tokamak reactor have been developed and are now entering the manufacturing stage.

@article{he_fabrication_2019,
	title = {Fabrication of {SiC} ceramic architectures using stereolithography combined with precursor infiltration and pyrolysis},
	volume = {45},
	issn = {0272-8842},
	doi = {10.1016/j.ceramint.2019.04.100},
	abstract = {Stereolithography based additive manufacturing provides a new route to produce ceramic architectures with complex geometries. In this study, 3D structured SiC ceramic architectures were fabricated by stereolithography based additive manufacturing combined with precursor infiltration and pyrolysis (PIP). Firstly, photosensitive SiC slurry was prepared. Then, stereolithography was conducted to fabricate complex-shaped green SiC parts. Polymer burn-out was subsequently performed, and porous SiC preforms were produced. After that, precursor infiltration and pyrolysis was used to improve the density and strength. Finally, 3D-structured SiC ceramic architectures with high accuracy and quality were obtained. It is believed that this study can give some fundamental understanding for the additive manufacturing of SiC ceramic structures.},
	number = {11},
	urldate = {2023-10-28},
	journal = {Ceramics International},
	author = {He, Rujie and Ding, Guojiao and Zhang, Keqiang and Li, Ying and Fang, Daining},
	month = aug,
	year = {2019},
	keywords = {Additive manufacturing, Precursor infiltration and pyrolysis, Silicon carbide, Stereolithography},
	pages = {14006--14014},
}

Stereolithography based additive manufacturing provides a new route to produce ceramic architectures with complex geometries. In this study, 3D structured SiC ceramic architectures were fabricated by stereolithography based additive manufacturing combined with precursor infiltration and pyrolysis (PIP). Firstly, photosensitive SiC slurry was prepared. Then, stereolithography was conducted to fabricate complex-shaped green SiC parts. Polymer burn-out was subsequently performed, and porous SiC preforms were produced. After that, precursor infiltration and pyrolysis was used to improve the density and strength. Finally, 3D-structured SiC ceramic architectures with high accuracy and quality were obtained. It is believed that this study can give some fundamental understanding for the additive manufacturing of SiC ceramic structures.

@inproceedings{sullivan2019,
	address = {Dallas, Texas},
	title = {Direct {Simulation} of {Fluid}-{Structure} {Interaction} in {Compression} {Ramp} with {Embedded} {Compliant} {Panel}},
	isbn = {978-1-62410-589-0},
	doi = {10.2514/6.2019-3545},
	language = {en},
	urldate = {2023-08-09},
	booktitle = {{AIAA} {Aviation} 2019 {Forum}},
	publisher = {AIAA Paper 2019-3545},
	author = {Sullivan, Bryson T. and Whalen, Thomas J. and Laurence, Stuart J. and Bodony, Daniel J.},
	month = jun,
	year = {2019},
}

@article{casper2019,
	title = {Hypersonic {Fluid}–{Structure} {Interactions} {Due} to {Intermittent} {Turbulent} {Spots} on a {Slender} {Cone}},
	volume = {57},
	issn = {0001-1452},
	doi = {10.2514/1.J057374},
	abstract = {Fluid–structure interactions due to intermittent turbulent spots were studied on a 7 deg half-angle cone in the Sandia Hypersonic Wind Tunnel at Mach 5 and 8 and in the Purdue Boeing/U.S. Air Force Office of Scientific Research Mach 6 Quiet Tunnel. A thin composite panel was integrated into the cone and the response to boundary-layer disturbances was characterized by accelerometers on the backside of the panel. Under quiet flow conditions at Mach 6, the cone boundary layer remained laminar. Artificially generated turbulent spots excited a directionally dependent panel response. When the spot generation frequency matched a structural natural frequency of the panel, resonance would occur, and responses over 200 times greater than under a laminar boundary layer were obtained. At Mach 5 and 8 under noisy flow conditions, natural transition driven by the wind-tunnel acoustic noise dominated the panel response. A single turbulent spot could not change this forced response. However, at higher spot burst rates, an elevated vibrational response was observed during transition at frequencies corresponding to the distribution of turbulent spots in the transitional flow. Once turbulent flow developed, the structural response dropped because the intermittent forcing from the spots no longer drove panel vibration.},
	number = {2},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {Casper, Katya M. and Beresh, Steven J. and Henfling, John F. and Spillers, Russell W. and Hunter, Patrick and Spitzer, Seth},
	year = {2019},
	note = {Publisher: American Institute of Aeronautics and Astronautics
\_eprint: https://doi.org/10.2514/1.J057374},
	pages = {749--759},
}

Fluid–structure interactions due to intermittent turbulent spots were studied on a 7 deg half-angle cone in the Sandia Hypersonic Wind Tunnel at Mach 5 and 8 and in the Purdue Boeing/U.S. Air Force Office of Scientific Research Mach 6 Quiet Tunnel. A thin composite panel was integrated into the cone and the response to boundary-layer disturbances was characterized by accelerometers on the backside of the panel. Under quiet flow conditions at Mach 6, the cone boundary layer remained laminar. Artificially generated turbulent spots excited a directionally dependent panel response. When the spot generation frequency matched a structural natural frequency of the panel, resonance would occur, and responses over 200 times greater than under a laminar boundary layer were obtained. At Mach 5 and 8 under noisy flow conditions, natural transition driven by the wind-tunnel acoustic noise dominated the panel response. A single turbulent spot could not change this forced response. However, at higher spot burst rates, an elevated vibrational response was observed during transition at frequencies corresponding to the distribution of turbulent spots in the transitional flow. Once turbulent flow developed, the structural response dropped because the intermittent forcing from the spots no longer drove panel vibration.

@article{currao2019,
	title = {Hypersonic {Fluid}–{Structure} {Interaction} on a {Cantilevered} {Plate} with {Shock} {Impingement}},
	volume = {57},
	issn = {0001-1452},
	doi = {10.2514/1.J058375},
	abstract = {This work is focused on a hypersonic aeroelastic experiment involving a shock impinging on compliant cantilevered plate at Mach 5.8. The shock induces a pressure differential across the plate thickness that drives its oscillatory behavior. Transition takes place within the separated region, resulting in a fully turbulent boundary layer at the reattachment point, in agreement with previous relevant work. A schlieren system and pressure-sensitive paint are used to measure structural displacement and pressure distribution, respectively. For small deflections, transition results in peak pressure values 15\% greater than twoway predictions based on unsteady Reynolds-averaged Navier–Stokes (RANS) equations. Peak pressure evolution is predicted with the piston theory with good accuracy. The reference enthalpy method is corrected on the basis of the Reynolds-averaged Navier–Stokes solution, and it is used to estimate the heat-flux distribution downstream of the reattachment point. Görtler-like vortices are observed and measured in the reattachment region, and their magnitude is affected by the plate deflection. Large trailing-edge displacements result in a smaller streamline curvature at the reattachment point and, consequently, in smaller vortices. Finally, the data are used to predict the performance of two-dimensional control surfaces using the conceptual equivalence of oblique shock-wave/boundary-layer interaction and compression corners. This work aims to establish the accuracy of RANS simulations and low-fidelity models in the reconstruction of the peak heating and peak pressure evolution to bridge ground-testing and real-flight conditions in terms of flap-efficiency predictions and to design an experiment that can be simulated using computationally inexpensive two-dimensional solvers.},
	number = {11},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {Currao, Gaetano M. D. and Neely, Andrew J. and Kennell, Christopher M. and Gai, Sudhir L. and Buttsworth, David R.},
	year = {2019},
	pages = {4819--4834},
}

This work is focused on a hypersonic aeroelastic experiment involving a shock impinging on compliant cantilevered plate at Mach 5.8. The shock induces a pressure differential across the plate thickness that drives its oscillatory behavior. Transition takes place within the separated region, resulting in a fully turbulent boundary layer at the reattachment point, in agreement with previous relevant work. A schlieren system and pressure-sensitive paint are used to measure structural displacement and pressure distribution, respectively. For small deflections, transition results in peak pressure values 15% greater than twoway predictions based on unsteady Reynolds-averaged Navier–Stokes (RANS) equations. Peak pressure evolution is predicted with the piston theory with good accuracy. The reference enthalpy method is corrected on the basis of the Reynolds-averaged Navier–Stokes solution, and it is used to estimate the heat-flux distribution downstream of the reattachment point. Görtler-like vortices are observed and measured in the reattachment region, and their magnitude is affected by the plate deflection. Large trailing-edge displacements result in a smaller streamline curvature at the reattachment point and, consequently, in smaller vortices. Finally, the data are used to predict the performance of two-dimensional control surfaces using the conceptual equivalence of oblique shock-wave/boundary-layer interaction and compression corners. This work aims to establish the accuracy of RANS simulations and low-fidelity models in the reconstruction of the peak heating and peak pressure evolution to bridge ground-testing and real-flight conditions in terms of flap-efficiency predictions and to design an experiment that can be simulated using computationally inexpensive two-dimensional solvers.

@article{huang2019,
	title = {Aerothermoelastic {Scaling} {Laws} for {Hypersonic} {Skin} {Panel} {Configurations} with {Arbitrary} {Flow} {Orientation}},
	volume = {57},
	issn = {0001-1452},
	doi = {10.2514/1.J057499},
	abstract = {This study describes the development of an efficient aerothermoelastic computational framework and its application to the aerothermoelastic scaling law development. In the framework, a novel approach is developed for the reduced-order model of the fluid solver, which accounts for nonuniform temperature distribution and geometrical scales using simple analytical pointwise models. Subsequently, a new, two-pronged approach to aerothermoelastic scaling is presented. It combines the classical scaling approach with augmentation from numerical simulations of the specific problem. This enables one to obtain useful scaling information for important quantities that cannot be treated by the classical approach. Finally, the framework is applied to study the effect of flow orientation angle on panel flutter and the development of a scaling law for a hypersonic skin panel configuration.},
	number = {10},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {Huang, Daning and Friedmann, Peretz P. and Rokita, Tomer},
	year = {2019},
	pages = {4377--4392},
}

This study describes the development of an efficient aerothermoelastic computational framework and its application to the aerothermoelastic scaling law development. In the framework, a novel approach is developed for the reduced-order model of the fluid solver, which accounts for nonuniform temperature distribution and geometrical scales using simple analytical pointwise models. Subsequently, a new, two-pronged approach to aerothermoelastic scaling is presented. It combines the classical scaling approach with augmentation from numerical simulations of the specific problem. This enables one to obtain useful scaling information for important quantities that cannot be treated by the classical approach. Finally, the framework is applied to study the effect of flow orientation angle on panel flutter and the development of a scaling law for a hypersonic skin panel configuration.

@inproceedings{mullen2019,
	address = {Dallas, Texas},
	title = {Heat {Transfer} and {Boundary}-{Layer} {Stability} {Analysis} of {Subscale} {BOLT} and the {Fin} {Cone}},
	isbn = {978-1-62410-589-0},
	doi = {10.2514/6.2019-3081},
	language = {en},
	urldate = {2023-06-22},
	booktitle = {{AIAA} {Aviation} 2019 {Forum}},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Mullen, Charles D. and Moyes, Alexander and Kocian, Travis S. and Reed, Helen L.},
	month = jun,
	year = {2019},
}

@article{grover2019a,
	title = {Vibrational energy transfer and collision-induced dissociation in {O} + {O2} collisions},
	volume = {33},
	url = {https://arc.aiaa.org/doi/10.2514/1.T5551},
	doi = {10.2514/1.T5551/ASSET/IMAGES/LARGE/FIGURE12.JPEG},
	abstract = {This paper presents molecular dynamics calculations of vibrational energy transfer and nonequilibrium dissociation in O2 + O collisions. The O2 + O interactions are modeled using nine potential energy surfaces corresponding to the 11A', 21A', 11A' 0, 13A', 23A', 13A", 15A', 25A', and 15A" states, which govern electronically adiabatic collisions of ground-electronic-state collisions of diatomic oxygen with atomic oxygen. Characteristic vibrational excitation times are calculated over a temperature range of T = 3000 K to T = 15,000 K, and nonequilibrium dissociation rate coefficients are calculated over a temperature range of T = 6000 K to T = 15,000 K. Vibrational relaxation rates, specific to each PES, are found to vary by over an order of magnitude, indicating that all spin couplings and spatial degeneracies must be considered for accurate predictions of O2 + O collisions. It has been observed that the characteristic vibrational excitation time for O2 + O interactions is weakly dependent on temperature and increases slightly with increasing temperature. Predicted nonequilibrium dissociation rates, during quasi-steady state. Agree well with available experimental data, and the coupling between vibrational energy and dissociation is characterized.},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Grover, Maninder S. and Schwartzentruber, Thomas E. and Varga, Zoltan and Truhlar, Donald G.},
	month = feb,
	year = {2019},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Born Oppenheimer Approximation, CFD, Collision Induced Dissociation, Direct Simulation Monte Carlo, Energy Distribution, Flight Testing, Hypersonic Flight, Lennard Jones Potential, Molecular Dynamics, Quasi Steady States},
	pages = {797--807},
}

This paper presents molecular dynamics calculations of vibrational energy transfer and nonequilibrium dissociation in O2 + O collisions. The O2 + O interactions are modeled using nine potential energy surfaces corresponding to the 11A', 21A', 11A' 0, 13A', 23A', 13A", 15A', 25A', and 15A" states, which govern electronically adiabatic collisions of ground-electronic-state collisions of diatomic oxygen with atomic oxygen. Characteristic vibrational excitation times are calculated over a temperature range of T = 3000 K to T = 15,000 K, and nonequilibrium dissociation rate coefficients are calculated over a temperature range of T = 6000 K to T = 15,000 K. Vibrational relaxation rates, specific to each PES, are found to vary by over an order of magnitude, indicating that all spin couplings and spatial degeneracies must be considered for accurate predictions of O2 + O collisions. It has been observed that the characteristic vibrational excitation time for O2 + O interactions is weakly dependent on temperature and increases slightly with increasing temperature. Predicted nonequilibrium dissociation rates, during quasi-steady state. Agree well with available experimental data, and the coupling between vibrational energy and dissociation is characterized.

@misc{hara2019,
	address = {SIAM Conference on Computational Science and Engineering},
	type = {Conference {Presentation}},
	title = {Verification {Test} {Cases} of {Grid}-{Based} {Direct} {Kinetic} {Modeling} {Framework} for {Plasma} {Flows}},
	author = {Hara, Kentaro and Hanquist, Kyle M.},
	year = {2019},
	keywords = {own, presentation},
}

@article{bezverkhnii2019,
	title = {Study of the {Effect} of {Electron} {Cooling}: {Overview} of the {Current} {State}},
	volume = {64},
	url = {https://link.springer.com/article/10.1134/S106378421903006X},
	doi = {10.1134/S106378421903006X},
	abstract = {Investigation results of the effect of electron cooling are considered. The current state-of-the-art is analyzed. The possibilities are discussed for the experimental study of the electron cooling phenomenon using a large shock tube and plasma-gas-dynamic stand at the Ioffe Institute.},
	number = {3},
	journal = {Technical Physics 2019 64:3},
	author = {Bezverkhnii, N. O. and Bobashev, S. V. and Kolychev, A. V. and Monakhov, N. A. and Ponyaev, S. A. and Sakharov, V. A.},
	month = may,
	year = {2019},
	note = {Publisher: Springer},
	keywords = {Classical and Continuum Physics},
	pages = {287--292},
}

Investigation results of the effect of electron cooling are considered. The current state-of-the-art is analyzed. The possibilities are discussed for the experimental study of the electron cooling phenomenon using a large shock tube and plasma-gas-dynamic stand at the Ioffe Institute.

@techreport{debrey2019,
	title = {Status and {Trends} in the {Education} of {Racial} and {Ethnic} {Groups} 2018},
	author = {de Brey, Cristobal and Musu, Lauren and McFarland, Joel and Wilkinson-Flicker, Sidney and Diliberti, Melissa and Zhang, Anlan and Branstetter, Claire and Wang, Xiaolei},
	year = {2019},
	note = {Issue: NCES 2019-038},
}

@inproceedings{wu2019,
	title = {Space and time analysis of \{{N}\}{\textbackslash}textsubscript\{2\} vibrational nonequilibrium in the \{{N}\}{\textbackslash}textsubscript\{2\} and air nanosecond discharge afterglow},
	author = {Wu, Y and Limbach, C M and Tropina, A A and Miles, R B},
	year = {2019},
}

@article{eyi2019d,
	title = {Shape {Optimization} of {Reentry} {Vehicles} to {Minimize} {Heat} {Loading}},
	volume = {33},
	doi = {10.2514/1.T5705},
	abstract = {The objective of the current study is to designanoptimumreentry vehicle shape thatminimizes heat loading subject to constraints on themaximumvalues of surface heat flux and temperature. A new heat loading formulation is developed for objective function evaluations. Axisymmetric Navier-Stokes and finite-rate chemical reaction equations are solved to evaluate the objectiveandconstraint functions.TheMenterSSTturbulencemodel isemployedfor turbulence closure. A gradient-based method is used for optimization. The sensitivities of the objective and constraint functions are evaluated using the finite-difference method. In shape optimization, the geometry change or the geometry itself is parameterized using different numbers of nonuniform rational basis spline (NURBS) or Bezier curves. Designs are performed at different trajectory points of the IRV-2 vehicle. The effects of flight path angle and reentry velocity on the heat transfer and trajectory characteristics of the original and designed geometries are quantified.},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Eyi, Sinan and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {own},
	pages = {785--796},
}

The objective of the current study is to designanoptimumreentry vehicle shape thatminimizes heat loading subject to constraints on themaximumvalues of surface heat flux and temperature. A new heat loading formulation is developed for objective function evaluations. Axisymmetric Navier-Stokes and finite-rate chemical reaction equations are solved to evaluate the objectiveandconstraint functions.TheMenterSSTturbulencemodel isemployedfor turbulence closure. A gradient-based method is used for optimization. The sensitivities of the objective and constraint functions are evaluated using the finite-difference method. In shape optimization, the geometry change or the geometry itself is parameterized using different numbers of nonuniform rational basis spline (NURBS) or Bezier curves. Designs are performed at different trajectory points of the IRV-2 vehicle. The effects of flight path angle and reentry velocity on the heat transfer and trajectory characteristics of the original and designed geometries are quantified.

@inproceedings{eyi2019e,
	title = {Shape {Optimization} of {Reentry} {Vehicles} to {Minimize} {Heat} {Loading}},
	doi = {10.2514/6.2019-0973},
	abstract = {The objective of the current study is to design an optimum reentry vehicle shape that minimizes heat loading subject to constraints on the maximum values of surface heat flux and temperature. A new formulation is developed for the heat loading calculations. Axisymmetric Navier-Stokes and finite rate chemical reaction equations are solved to evaluate the objective and constraint functions. The Menter SST turbulence model is employed for turbulence closure. A gradient-based method is utilized for optimization. The sensitivities of the objective and constraint functions are evaluated using the finite difference method. In design optimization, the geometry change or the geometry itself is parameterized using different numbers of NURBS or Bezier curves. Designs are performed at different trajectory points of the IRV-2 vehicle. The effects of flight path angle and reentry velocity on the heat transfer and trajectory characteristics of the original and designed geometries are quantified.},
	booktitle = {{AIAA} {Science} and {Technology} {Forum} and {Exposition}},
	publisher = {AIAA Paper 2019-0973},
	author = {Eyi, Sinan and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {own},
}

The objective of the current study is to design an optimum reentry vehicle shape that minimizes heat loading subject to constraints on the maximum values of surface heat flux and temperature. A new formulation is developed for the heat loading calculations. Axisymmetric Navier-Stokes and finite rate chemical reaction equations are solved to evaluate the objective and constraint functions. The Menter SST turbulence model is employed for turbulence closure. A gradient-based method is utilized for optimization. The sensitivities of the objective and constraint functions are evaluated using the finite difference method. In design optimization, the geometry change or the geometry itself is parameterized using different numbers of NURBS or Bezier curves. Designs are performed at different trajectory points of the IRV-2 vehicle. The effects of flight path angle and reentry velocity on the heat transfer and trajectory characteristics of the original and designed geometries are quantified.

@article{dwivedi2019,
	title = {Reattachment streaks in hypersonic compression ramp flow: an input–output analysis},
	volume = {880},
	doi = {10.1017/JFM.2019.702},
	abstract = {We employ global input–output analysis to quantify amplification of exogenous disturbances in compressible boundary layer flows. Using the spatial structure of the dominant response to time-periodic inputs, we explain the origin of steady reattachment streaks in a hypersonic flow over a compression ramp. Our analysis of the laminar shock–boundary layer interaction reveals that the streaks arise from a preferential amplification of upstream counter-rotating vortical perturbations with a specific spanwise wavelength. These streaks are associated with heat-flux striations at the wall near flow reattachment and they can trigger transition to turbulence. The streak wavelength predicted by our analysis compares favourably with observations from two different hypersonic compression ramp experiments. Furthermore, our analysis of inviscid transport equations demonstrates that base-flow deceleration contributes to the amplification of streamwise velocity and that the baroclinic effects are responsible for the production of streamwise vorticity. Finally, the appearance of the temperature streaks near reattachment is triggered by the growth of streamwise velocity and streamwise vorticity perturbations as well as by the amplification of upstream temperature perturbations by the reattachment shock.},
	journal = {Journal of Fluid Mechanics},
	author = {Dwivedi, Anubhav and Sidharth, G. S. and Nichols, Joseph W. and Candler, Graham V. and Jovanović, Mihailo R.},
	year = {2019},
	note = {Publisher: Cambridge University Press},
	keywords = {compressible boundary layers, high-speed flow, transition to turbulence},
	pages = {113--135},
}

We employ global input–output analysis to quantify amplification of exogenous disturbances in compressible boundary layer flows. Using the spatial structure of the dominant response to time-periodic inputs, we explain the origin of steady reattachment streaks in a hypersonic flow over a compression ramp. Our analysis of the laminar shock–boundary layer interaction reveals that the streaks arise from a preferential amplification of upstream counter-rotating vortical perturbations with a specific spanwise wavelength. These streaks are associated with heat-flux striations at the wall near flow reattachment and they can trigger transition to turbulence. The streak wavelength predicted by our analysis compares favourably with observations from two different hypersonic compression ramp experiments. Furthermore, our analysis of inviscid transport equations demonstrates that base-flow deceleration contributes to the amplification of streamwise velocity and that the baroclinic effects are responsible for the production of streamwise vorticity. Finally, the appearance of the temperature streaks near reattachment is triggered by the growth of streamwise velocity and streamwise vorticity perturbations as well as by the amplification of upstream temperature perturbations by the reattachment shock.

@article{hanquist2019c,
	title = {Plasma {Assisted} {Cooling} of {Hot} {Surfaces} on {Hypersonic} {Vehicles}},
	volume = {7},
	doi = {10.3389/fphy.2019.00009},
	abstract = {Electron transpiration cooling (ETC) is a proposed thermal management approach for the leading edges of hypersonic vehicles that utilizes thermionic emission to emit electrons to carry heat away from the surface. A modeling approach is presented for assessing ETC in a computational fluid dynamics (CFD) framework and is evaluated using previously completed experiments. The modeling approach presented includes developing boundary conditions to account for space-charge-limited emission to accurately determine the level of electron emission from the surface. The effectiveness of ETC for multiple test cases are investigated including sharp leading edges and blunt bodies. For each of these test cases, ETC affects the surface properties, most notably the surface temperature, suggesting that ETC occurs for bodies in thermally intense, ionized flows, no matter the shape of the leading edge. An approximate approach is also presented to assess ETC in an ionized flow and compares its cooling power to radiative cooling.},
	number = {9},
	journal = {Frontiers in Physics: Plasma for Aerospace},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {Computational fluid dynamics, Electron transpiration cooling, Hypersonics, Plasma sheath, Thermionic emission, etc, own},
	pages = {1--13},
}

Electron transpiration cooling (ETC) is a proposed thermal management approach for the leading edges of hypersonic vehicles that utilizes thermionic emission to emit electrons to carry heat away from the surface. A modeling approach is presented for assessing ETC in a computational fluid dynamics (CFD) framework and is evaluated using previously completed experiments. The modeling approach presented includes developing boundary conditions to account for space-charge-limited emission to accurately determine the level of electron emission from the surface. The effectiveness of ETC for multiple test cases are investigated including sharp leading edges and blunt bodies. For each of these test cases, ETC affects the surface properties, most notably the surface temperature, suggesting that ETC occurs for bodies in thermally intense, ionized flows, no matter the shape of the leading edge. An approximate approach is also presented to assess ETC in an ionized flow and compares its cooling power to radiative cooling.

@article{candler2019,
	title = {Rate {Effects} in {Hypersonic} {Flows}},
	volume = {51},
	issn = {0066-4189},
	doi = {10.1146/annurev-fluid-010518-040258},
	abstract = {Hypersonic flows are energetic and result in regions of high temperature, causing internal energy excitation, chemical reactions, ionization, and gas-surface interactions. At typical flight conditions, the rates of these processes are often similar to the rate of fluid motion. Thus, the gas state is out of local thermodynamic equilibrium and must be described by conservation equations for the internal energy and chemical state. Examples illustrate how competition between rates in hypersonic flows can affect aerodynamic performance, convective heating, boundary layer transition, and ablation. The conservation equations are outlined, and the most widely used models for internal energy relaxation, reaction rates, and transport properties are reviewed. Gas-surface boundary conditions are described, including finite-rate catalysis and slip effects. Recent progress in the use of first-principles calculations to understand and quantify critical gas-phase reactions is discussed. An advanced finite-rate carbon ablation model is introduced and is used to illustrate the role of rate processes at hypersonic conditions.},
	number = {1},
	urldate = {2021-02-15},
	journal = {Annual Review of Fluid Mechanics},
	author = {Candler, Graham V.},
	year = {2019},
	note = {Publisher: Annual Reviews Inc.},
	keywords = {aerothermodynamics, finite-rate processes, high-temperature gas dynamics, hypersonic aerodynamics, nonequilibrium flows},
	pages = {379--402},
}

Hypersonic flows are energetic and result in regions of high temperature, causing internal energy excitation, chemical reactions, ionization, and gas-surface interactions. At typical flight conditions, the rates of these processes are often similar to the rate of fluid motion. Thus, the gas state is out of local thermodynamic equilibrium and must be described by conservation equations for the internal energy and chemical state. Examples illustrate how competition between rates in hypersonic flows can affect aerodynamic performance, convective heating, boundary layer transition, and ablation. The conservation equations are outlined, and the most widely used models for internal energy relaxation, reaction rates, and transport properties are reviewed. Gas-surface boundary conditions are described, including finite-rate catalysis and slip effects. Recent progress in the use of first-principles calculations to understand and quantify critical gas-phase reactions is discussed. An advanced finite-rate carbon ablation model is introduced and is used to illustrate the role of rate processes at hypersonic conditions.

@article{raissi2019,
	title = {Physics-informed neural networks: {A} deep learning framework for solving forward and inverse problems involving nonlinear partial differential equations},
	volume = {378},
	journal = {Journal of Computational Physics},
	author = {Raissi, M and Perdikaris, P and Karniadakis, G E},
	year = {2019},
}

@techreport{brandis2019,
	title = {{NEQAIR} v15.0 {Release} {Notes}: {Nonequilibrium} and {Equilibrium} {Radiative} {Transport} and {Spectra} {Program}},
	author = {Brandis, Aaron M and Cruden, Brett A},
	year = {2019},
	note = {Issue: ARC-E-DAA-TN72963},
}

@misc{hanquist2019a,
	address = {Department of Aerospace Engineering, Penn State University},
	type = {Invited {Seminar}},
	title = {Modeling of {Nonequilibrium} {Gas} and {Plasma} with {Applications} to {Hypersonics}},
	author = {Hanquist, Kyle M.},
	year = {2019},
	keywords = {invited, own},
}

@article{josyula2019,
	title = {Multiquantum {Transitions} in {Oxygen} and {Nitrogen} {Molecules} in {Hypersonic} {Nonequilibrium} {Flows}},
	volume = {33},
	doi = {10.2514/1.T5444},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Josyula, Eswar and Suchyta, Casimir J and Vedula, Prakash and Burt, Jonathan M},
	year = {2019},
	pages = {378--391},
}

@inproceedings{hanquist2019b,
	title = {Modeling of {Electronically} {Excited} {Oxygen} in {O}$_{\textrm{2}}$ -{Ar} {Shock} {Tube} {Studies}},
	doi = {10.2514/6.2019-3567},
	booktitle = {{AIAA} {Aviation} 2019 {Forum}},
	publisher = {AIAA Paper 2019-3567},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {own},
}

@inproceedings{streicher2019,
	address = {San Diego, CA},
	title = {Measurements of {Oxygen} {Vibrational} {Relaxation} and {Dissociation} {Using} {Ultraviolet} {Laser} {Absorption} in {Shock} {Tube} {Experiments}},
	publisher = {\{AIAA Paper\} 2019-0795},
	author = {Streicher, J W and Krish, A and Wang, S and Davidson, D F and Hanson, R K},
	month = jan,
	year = {2019},
	pages = {1--11},
}

@article{boccelli2019,
	title = {Lagrangian diffusive reactor for detailed thermochemical computations of plasma flows},
	volume = {28},
	doi = {10.1088/1361-6595/AB09B5},
	abstract = {The simulation of a thermochemical nonequilibrium for atomic and molecular energy level populations in plasma flows requires a comprehensive modeling of all the elementary collisional and radiative processes involved. Coupling detailed chemical mechanisms to flow solvers is computationally expensive and often limits their application to 1D simulations. We develop an efficient Lagrangian diffusive reactor moving along the streamlines of a steady baseline flow simulation to compute detailed thermochemical effects. In addition to its efficiency, the method allows us to model both continuum and rarefied flows, while including mass and energy diffusion. The Lagrangian solver is assessed for several testcases including strong normal shockwaves, as well as 2D and axisymmetric blunt-body hypersonic rarefied flows. In all the testcases performed, the Lagrangian reactor improves drastically the baseline simulations. The computational cost of a Lagrangian recomputation is typically orders of magnitude smaller with respect to a full solution of the problem. The solver has the additional benefit of being immune from statistical noise, which strongly affects the accuracy of calculations obtained by means of the Direct Simulation Monte Carlo method, especially considering minor species in the mixture. The results demonstrate that the method enables applying detailed mechanisms to multidimensional solvers to study thermochemical nonequilibrium flows.},
	number = {6},
	journal = {Plasma Sources Science and Technology},
	author = {Boccelli, Stefano and Bariselli, Federico and Dias, Bruno and Magin, Thierry E.},
	month = jun,
	year = {2019},
	note = {Publisher: IOP Publishing},
	keywords = {Lagrangian chemical reactor, Nonequilibrium plasmas, chemically reactive flows, rarefied gas dynamics},
}

The simulation of a thermochemical nonequilibrium for atomic and molecular energy level populations in plasma flows requires a comprehensive modeling of all the elementary collisional and radiative processes involved. Coupling detailed chemical mechanisms to flow solvers is computationally expensive and often limits their application to 1D simulations. We develop an efficient Lagrangian diffusive reactor moving along the streamlines of a steady baseline flow simulation to compute detailed thermochemical effects. In addition to its efficiency, the method allows us to model both continuum and rarefied flows, while including mass and energy diffusion. The Lagrangian solver is assessed for several testcases including strong normal shockwaves, as well as 2D and axisymmetric blunt-body hypersonic rarefied flows. In all the testcases performed, the Lagrangian reactor improves drastically the baseline simulations. The computational cost of a Lagrangian recomputation is typically orders of magnitude smaller with respect to a full solution of the problem. The solver has the additional benefit of being immune from statistical noise, which strongly affects the accuracy of calculations obtained by means of the Direct Simulation Monte Carlo method, especially considering minor species in the mixture. The results demonstrate that the method enables applying detailed mechanisms to multidimensional solvers to study thermochemical nonequilibrium flows.

@article{niu2019,
	title = {Infrared radiation characteristics of a hypersonic vehicle under time-varying angles of attack},
	volume = {32},
	doi = {10.1016/j.cja.2019.01.003},
	abstract = {Hypersonic vehicles emit strong infrared (IR) radiation signatures that can be treated as a detecting source for object identification and routine diagnosis. This paper is aimed at examining the intrinsic radiation characteristics of a Boost-Glide Vehicle (BGV) under the condition of various Angles of Attack (AOAs). A two-temperature model considering the thermal and chemical non-equilibrium effects is coupled with Navier-Stokes equations solved by the finite volume technique. A gas–solid conjunction heat transfer model is also added into the fluid solver to simulate the surface temperature of the vehicle. The radiative transfer equation is solved with Line of Sight (LOS) algorithm. The computational results for a Hypersonic Technology Vehicle-2 (HTV-2) type vehicle show that radiances of the vehicle are strongly dependent on the surface temperature. The presence of AOA results in the significant difference of the surface temperature. Infrared radiation characteristics are also changed in intensity and spectral band due to the AOA. Simulations are performed with two time-varying AOAs. Transient results indicate that the variation of AOA does have a great effect on the infrared radiance and is closely related to observation angle, spectral band, angle size, angular velocity and time history.},
	number = {4},
	journal = {Chinese Journal of Aeronautics},
	author = {Niu, Qinglin and Yuan, Zhichao and Chen, Biao and Dong, Shikui},
	year = {2019},
	note = {Publisher: Chinese Journal of Aeronautics},
	keywords = {Angle of attack, Fluid-thermal interaction, HTV-2, Hypersonic vehicle, IR radiation, Surface temperature},
	pages = {861--874},
}

Hypersonic vehicles emit strong infrared (IR) radiation signatures that can be treated as a detecting source for object identification and routine diagnosis. This paper is aimed at examining the intrinsic radiation characteristics of a Boost-Glide Vehicle (BGV) under the condition of various Angles of Attack (AOAs). A two-temperature model considering the thermal and chemical non-equilibrium effects is coupled with Navier-Stokes equations solved by the finite volume technique. A gas–solid conjunction heat transfer model is also added into the fluid solver to simulate the surface temperature of the vehicle. The radiative transfer equation is solved with Line of Sight (LOS) algorithm. The computational results for a Hypersonic Technology Vehicle-2 (HTV-2) type vehicle show that radiances of the vehicle are strongly dependent on the surface temperature. The presence of AOA results in the significant difference of the surface temperature. Infrared radiation characteristics are also changed in intensity and spectral band due to the AOA. Simulations are performed with two time-varying AOAs. Transient results indicate that the variation of AOA does have a great effect on the infrared radiance and is closely related to observation angle, spectral band, angle size, angular velocity and time history.

@article{tropina2019,
	title = {Influence of vibrational non-equilibrium on the polarizability and refraction index in air: computational study},
	volume = {53},
	number = {10},
	journal = {Journal of Physics D: Applied Physics},
	author = {Tropina, Albina A and Wu, Yue and Limbach, Christopher M and Miles, Richard B},
	month = dec,
	year = {2019},
	pages = {105201--105201},
}

@article{rafanocarna2019,
	title = {High fidelity model for the atmospheric re-entry of {CubeSats} equipped with the {Drag} {De}-{Orbit} {Device}},
	volume = {156},
	doi = {10.1016/j.actaastro.2018.05.049},
	abstract = {The use of CubeSat-like small satellites is growing exponentially nowadays, pushing towards missions of increased complexity, including Earth imaging, commercial communications and astronomical observations. As such, they might require components that may survive the re-entry conditions and reach the ground, posing risks for population and properties, or that are intended to be retrieved. The possibility of demise and ground impact poses many challenges from the modeling standpoint because of the uncertainties associated with both the aero- and the aerothermo-dynamic models of the spacecraft. Several formulations and correlations can be found in the literature. Most of them are derived in dated and difficult-to-access papers and technical reports. This paper collects all the necessary and sufficient models, laws and data to describe in a comprehensive way the re-entry of small satellites. They are presented in an organized fashion, with uniform nomenclature and consistent assumptions in order to provide the smallsats scientific community with a smallsats specific, easy-to-understand and rapid-to-implement tool. Furthermore, the paper originally presents an approximated aero- and aerothermo-dynamic model of the Drag De-Orbit Device, a recently developed drag modulation device for drag-based controlled re-entry of large CubeSats.},
	journal = {Acta Astronautica},
	author = {Rafano Carná, S. F. and Bevilacqua, R.},
	month = mar,
	year = {2019},
	note = {Publisher: Elsevier Ltd},
	keywords = {Aerodynamic model, Aerothermodynamic model, Atmospheric re-entry modeling, CubeSats, Drag De-Orbit Device},
	pages = {134--156},
}

The use of CubeSat-like small satellites is growing exponentially nowadays, pushing towards missions of increased complexity, including Earth imaging, commercial communications and astronomical observations. As such, they might require components that may survive the re-entry conditions and reach the ground, posing risks for population and properties, or that are intended to be retrieved. The possibility of demise and ground impact poses many challenges from the modeling standpoint because of the uncertainties associated with both the aero- and the aerothermo-dynamic models of the spacecraft. Several formulations and correlations can be found in the literature. Most of them are derived in dated and difficult-to-access papers and technical reports. This paper collects all the necessary and sufficient models, laws and data to describe in a comprehensive way the re-entry of small satellites. They are presented in an organized fashion, with uniform nomenclature and consistent assumptions in order to provide the smallsats scientific community with a smallsats specific, easy-to-understand and rapid-to-implement tool. Furthermore, the paper originally presents an approximated aero- and aerothermo-dynamic model of the Drag De-Orbit Device, a recently developed drag modulation device for drag-based controlled re-entry of large CubeSats.

@article{spottswood2019,
	title = {Exploring the response of a thin, flexible panel to shock-turbulent boundary-layer interactions},
	volume = {443},
	doi = {10.1016/J.JSV.2018.11.035},
	abstract = {The use of nonlinear, dynamic methods for the simulation of aerospace structures has increased dramatically in recent years [1]; however, very little relevant experimental data exists to properly guide these developments. An experimental campaign was initiated by the AFRL Structural Sciences Center (SSC) for three reasons: (1) to observe and measure the effect of turbulence, shock boundary-layer interactions (SBLI) and heated flow on an aircraft-like panel; (2) to explore severe structural events (dynamic instabilities and material failure); and (3) to refine full-field and non-contacting experimental measurement techniques necessary to characterize the flow environment and structural response. All of the objectives were achieved. The panel response to turbulent, heated flow and sensitivity to panel back-pressure modulation was studied, with large-deformation limit cycle behavior leading to panel failure, observed and measured. For the first time, the 3D Digital Image Correlation (DIC) technique was also used to record the panel behavior while filming through the flow and SBLI environment. Finally, fast reacting pressure sensitive paint (PSP) was used, concurrently with 3D DIC, to record the dynamic pressure across the panel surface.},
	journal = {Journal of Sound and Vibration},
	author = {Spottswood, S. Michael and Beberniss, Timothy J. and Eason, Thomas G. and Perez, Ricardo A. and Donbar, Jeffrey M. and Ehrhardt, David A. and Riley, Zachary B.},
	month = mar,
	year = {2019},
	note = {Publisher: Academic Press},
	keywords = {Fluid-structure interaction, Shock boundary-layer interaction, Sonic fatigue},
	pages = {74--89},
}

The use of nonlinear, dynamic methods for the simulation of aerospace structures has increased dramatically in recent years [1]; however, very little relevant experimental data exists to properly guide these developments. An experimental campaign was initiated by the AFRL Structural Sciences Center (SSC) for three reasons: (1) to observe and measure the effect of turbulence, shock boundary-layer interactions (SBLI) and heated flow on an aircraft-like panel; (2) to explore severe structural events (dynamic instabilities and material failure); and (3) to refine full-field and non-contacting experimental measurement techniques necessary to characterize the flow environment and structural response. All of the objectives were achieved. The panel response to turbulent, heated flow and sensitivity to panel back-pressure modulation was studied, with large-deformation limit cycle behavior leading to panel failure, observed and measured. For the first time, the 3D Digital Image Correlation (DIC) technique was also used to record the panel behavior while filming through the flow and SBLI environment. Finally, fast reacting pressure sensitive paint (PSP) was used, concurrently with 3D DIC, to record the dynamic pressure across the panel surface.

@article{thompson2019,
	title = {Eigenvector perturbation methodology for uncertainty quantification of turbulence models},
	volume = {4},
	url = {https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.4.044603},
	doi = {10.1103/PHYSREVFLUIDS.4.044603/FIGURES/9/MEDIUM},
	abstract = {Reynolds-averaged Navier-Stokes (RANS) models are the primary numerical recourse to investigate complex engineering turbulent flows in industrial applications. However, to establish RANS models as reliable design tools, it is essential to provide estimates for the uncertainty in their predictions. In the recent past, an uncertainty estimation framework relying on eigenvalue and eigenvector perturbations to the modeled Reynolds stress tensor has been widely applied with satisfactory results. However, the methodology for the eigenvector perturbations is not well established. Evaluations using only eigenvalue perturbations do not provide comprehensive estimates of model form uncertainty, especially in flows with streamline curvature, recirculation, or flow separation. In this article, we outline a methodology for the eigenvector perturbations using a predictor-corrector approach, which uses the incipient eigenvalue perturbations along with the Reynolds stress transport equations to determine the eigenvector perturbations. This approach was applied to benchmark cases of complex turbulent flows. The uncertainty intervals estimated using the proposed framework exhibited substantial improvement over eigenvalue-only perturbations and are able to account for a significant proportion of the discrepancy between RANS predictions and high-fidelity data.},
	number = {4},
	journal = {Physical Review Fluids},
	author = {Thompson, Roney L. and Mishra, Aashwin Ananda and Iaccarino, Gianluca and Edeling, Wouter and Sampaio, Luiz},
	month = apr,
	year = {2019},
	note = {Publisher: American Physical Society},
	pages = {044603--044603},
}

Reynolds-averaged Navier-Stokes (RANS) models are the primary numerical recourse to investigate complex engineering turbulent flows in industrial applications. However, to establish RANS models as reliable design tools, it is essential to provide estimates for the uncertainty in their predictions. In the recent past, an uncertainty estimation framework relying on eigenvalue and eigenvector perturbations to the modeled Reynolds stress tensor has been widely applied with satisfactory results. However, the methodology for the eigenvector perturbations is not well established. Evaluations using only eigenvalue perturbations do not provide comprehensive estimates of model form uncertainty, especially in flows with streamline curvature, recirculation, or flow separation. In this article, we outline a methodology for the eigenvector perturbations using a predictor-corrector approach, which uses the incipient eigenvalue perturbations along with the Reynolds stress transport equations to determine the eigenvector perturbations. This approach was applied to benchmark cases of complex turbulent flows. The uncertainty intervals estimated using the proposed framework exhibited substantial improvement over eigenvalue-only perturbations and are able to account for a significant proportion of the discrepancy between RANS predictions and high-fidelity data.

@article{plimpton2019,
	title = {Direct simulation {Monte} {Carlo} on petaflop supercomputers and beyond},
	volume = {31},
	doi = {10.1063/1.5108534},
	abstract = {The gold-standard definition of the Direct Simulation Monte Carlo (DSMC) method is given in the 1994 book by Bird [Molecular Gas Dynamics and the Direct Simulation of Gas Flows (Clarendon Press, Ox...},
	number = {8},
	journal = {Physics of Fluids},
	author = {Plimpton, S. J. and Moore, S. G. and Borner, A. and Stagg, A. K. and Koehler, T. P. and Torczynski, J. R. and Gallis, M. A.},
	month = aug,
	year = {2019},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	keywords = {Monte Carlo methods, flow simulation, rarefied fluid dynamics},
	pages = {086101--086101},
}

The gold-standard definition of the Direct Simulation Monte Carlo (DSMC) method is given in the 1994 book by Bird [Molecular Gas Dynamics and the Direct Simulation of Gas Flows (Clarendon Press, Ox...

@inproceedings{holloway2019b,
	title = {Effect of {Thermochemistry} {Modeling} on {Hypersonic} {Flow} {Over} a {Double} {Cone}},
	doi = {10.2514/6.2019-2281},
	abstract = {The influence of different assumptions for thermochemistry modeling in hypersonic flow over a double-cone geometry is investigated. The double-cone geometry is simple but produces a complex shock wave/boundary layer interaction and nonequilibrium flow physics. This interaction sig-nificantly impacts the aerothermodynamic loading, in terms of surface pressure and heat transfer. Therefore, it is important that these interactions can be predicted with physical accuracy and numerical efficiency. A CFD analysis is used to study the double-cone in three different thermochemical cases: nonequilibrium flow, equilibrium flow, and frozen flow for five different mixtures of nitrogen and oxygen. Specific areas of interest include the thermochemistry model effects on the flow field and surface properties. The resulting aerodynamic loads are compared to experiments and indicate that thermochemistry modeling assumptions play a significant role in determining surface properties. It is also shown that heat loading is more sensitive to thermochemical modeling than drag and suggests that an accurate measurement of surface heat transfer is of particular interest. Careful analysis also reveals that high enthalpy and pure oxygen flows are particularly sensitive to the thermochemistry model assumed.},
	booktitle = {{AIAA} {SCITECH} 2019 {Forum}},
	publisher = {AIAA Paper 2019-2281},
	author = {Holloway, Michael E. and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {own},
}

The influence of different assumptions for thermochemistry modeling in hypersonic flow over a double-cone geometry is investigated. The double-cone geometry is simple but produces a complex shock wave/boundary layer interaction and nonequilibrium flow physics. This interaction sig-nificantly impacts the aerothermodynamic loading, in terms of surface pressure and heat transfer. Therefore, it is important that these interactions can be predicted with physical accuracy and numerical efficiency. A CFD analysis is used to study the double-cone in three different thermochemical cases: nonequilibrium flow, equilibrium flow, and frozen flow for five different mixtures of nitrogen and oxygen. Specific areas of interest include the thermochemistry model effects on the flow field and surface properties. The resulting aerodynamic loads are compared to experiments and indicate that thermochemistry modeling assumptions play a significant role in determining surface properties. It is also shown that heat loading is more sensitive to thermochemical modeling than drag and suggests that an accurate measurement of surface heat transfer is of particular interest. Careful analysis also reveals that high enthalpy and pure oxygen flows are particularly sensitive to the thermochemistry model assumed.

@article{brune2019,
	title = {Computational predictions of the hypersonic material environmental test system arcjet facility},
	volume = {33},
	doi = {10.2514/1.T5490/ASSET/IMAGES/LARGE/FIGURE15.JPEG},
	abstract = {The Hypersonic Materials Environmental Test System arcjet facility located at theNASALangley Research Center in Hampton, Virginia, is primarily used for the research, development, and evaluation of high-temperature thermal protection systems for hypersonic vehicles and reentry systems. To improve testing capabilities and knowledge of the test article environment, a detailed three-dimensional model of the arcjet nozzle and the freejet portion of the flowfield is developed. The computational fluid dynamics model takes into account nonuniform inflow state profiles at the nozzle inlet as well as catalytic recombination efficiency effects at the probe surface. The results of the numerical simulations are compared to the calibrated pitot pressure and the stagnation-point heat flux for three test conditions at low, medium, and high enthalpies. Comparing the results and the test data indicates a partially catalytic copper surface on the heat flux probe of about 10\% recombination efficiency and a 2-3 kPa pressure drop from the total pressure measured at the plenum section in front of the nozzle. With these assumptions, the predictions are within the uncertainty of the stagnation pressure and heat flux measurements. The predicted velocity conditions at the nozzle exit are also compared and show good agreement with the radial and axial velocimetry data.},
	number = {1},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Brune, Andrew J. and Bruce, Walter E. and Glass, David E. and Splinter, Scott C.},
	month = sep,
	year = {2019},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Catalysis, Enthalpy, Heat Flux, Hypersonic Vehicles, Molecular Tagging Velocimetry, NASA Langley Research Center, Numerical Simulation, Slug Calorimeters, Stagnation Temperature, Thermal Protection System},
	pages = {199--209},
}

The Hypersonic Materials Environmental Test System arcjet facility located at theNASALangley Research Center in Hampton, Virginia, is primarily used for the research, development, and evaluation of high-temperature thermal protection systems for hypersonic vehicles and reentry systems. To improve testing capabilities and knowledge of the test article environment, a detailed three-dimensional model of the arcjet nozzle and the freejet portion of the flowfield is developed. The computational fluid dynamics model takes into account nonuniform inflow state profiles at the nozzle inlet as well as catalytic recombination efficiency effects at the probe surface. The results of the numerical simulations are compared to the calibrated pitot pressure and the stagnation-point heat flux for three test conditions at low, medium, and high enthalpies. Comparing the results and the test data indicates a partially catalytic copper surface on the heat flux probe of about 10% recombination efficiency and a 2-3 kPa pressure drop from the total pressure measured at the plenum section in front of the nozzle. With these assumptions, the predictions are within the uncertainty of the stagnation pressure and heat flux measurements. The predicted velocity conditions at the nozzle exit are also compared and show good agreement with the radial and axial velocimetry data.

@article{mackey2019a,
	title = {Assessment of hypersonic flow physics on aero-optics},
	volume = {57},
	issn = {00011452},
	url = {http://arc.aiaa.org},
	doi = {10.2514/1.J057869},
	abstract = {In a hypersonic environment, the high kinetic energy of the oncoming flow causes the molecules in the flow to be thermally excited, leadingto dissociation. In such a flow field, an aero-optical analysis that considers thermochemical nonequilibrium may be necessary to assist in sensor design. The present study assesses the optical properties of a nonequilibrium, real gas flow field around a hemisphere cylinder. The simulations are conducted at freestream Mach numbers of 11, 13, and 15. The optical distortions are quantified using optical path length and optical path difference. Optical distortion isalso predicted using a perfect gas assumption, and these distortions are provided for comparison. The primary contributions of nonequilibrium parameters on optical distortion are identified. For all Mach numbers, optical path lengths are higher when the effects of dissociation and vibrational relaxation are included. The computational results show that oxygen dissociation is the dominant nonequilibrium flow phenomena affecting the optical distortion. However, as the freestream Mach number increases, atomic nitrogen begins to have an additional influence on optical aberrations.},
	number = {9},
	urldate = {2021-05-31},
	journal = {AIAA Journal},
	author = {Mackey, Lauren E. and Boyd, Iain D.},
	month = jul,
	year = {2019},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Chemical Energy, Computational Fluid Dynamics Simulation, Energy Distribution, Freestream Mach Number, Gas Constant, Nonequilibrium Flows, Optical Properties, Optical Sensor, Stagnation Region, Stagnation Streamlines},
	pages = {3885--3897},
}

In a hypersonic environment, the high kinetic energy of the oncoming flow causes the molecules in the flow to be thermally excited, leadingto dissociation. In such a flow field, an aero-optical analysis that considers thermochemical nonequilibrium may be necessary to assist in sensor design. The present study assesses the optical properties of a nonequilibrium, real gas flow field around a hemisphere cylinder. The simulations are conducted at freestream Mach numbers of 11, 13, and 15. The optical distortions are quantified using optical path length and optical path difference. Optical distortion isalso predicted using a perfect gas assumption, and these distortions are provided for comparison. The primary contributions of nonequilibrium parameters on optical distortion are identified. For all Mach numbers, optical path lengths are higher when the effects of dissociation and vibrational relaxation are included. The computational results show that oxygen dissociation is the dominant nonequilibrium flow phenomena affecting the optical distortion. However, as the freestream Mach number increases, atomic nitrogen begins to have an additional influence on optical aberrations.

@article{mackey2019c,
	title = {Assessment of hypersonic flow physics on aero-optics},
	volume = {57},
	url = {http://arc.aiaa.org},
	doi = {10.2514/1.J057869},
	abstract = {In a hypersonic environment, the high kinetic energy of the oncoming flow causes the molecules in the flow to be thermally excited, leadingto dissociation. In such a flow field, an aero-optical analysis that considers thermochemical nonequilibrium may be necessary to assist in sensor design. The present study assesses the optical properties of a nonequilibrium, real gas flow field around a hemisphere cylinder. The simulations are conducted at freestream Mach numbers of 11, 13, and 15. The optical distortions are quantified using optical path length and optical path difference. Optical distortion isalso predicted using a perfect gas assumption, and these distortions are provided for comparison. The primary contributions of nonequilibrium parameters on optical distortion are identified. For all Mach numbers, optical path lengths are higher when the effects of dissociation and vibrational relaxation are included. The computational results show that oxygen dissociation is the dominant nonequilibrium flow phenomena affecting the optical distortion. However, as the freestream Mach number increases, atomic nitrogen begins to have an additional influence on optical aberrations.},
	number = {9},
	journal = {AIAA Journal},
	author = {Mackey, Lauren E. and Boyd, Iain D.},
	month = jul,
	year = {2019},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Chemical Energy, Computational Fluid Dynamics Simulation, Energy Distribution, Freestream Mach Number, Gas Constant, Nonequilibrium Flows, Optical Properties, Optical Sensor, Stagnation Region, Stagnation Streamlines},
	pages = {3885--3897},
}

In a hypersonic environment, the high kinetic energy of the oncoming flow causes the molecules in the flow to be thermally excited, leadingto dissociation. In such a flow field, an aero-optical analysis that considers thermochemical nonequilibrium may be necessary to assist in sensor design. The present study assesses the optical properties of a nonequilibrium, real gas flow field around a hemisphere cylinder. The simulations are conducted at freestream Mach numbers of 11, 13, and 15. The optical distortions are quantified using optical path length and optical path difference. Optical distortion isalso predicted using a perfect gas assumption, and these distortions are provided for comparison. The primary contributions of nonequilibrium parameters on optical distortion are identified. For all Mach numbers, optical path lengths are higher when the effects of dissociation and vibrational relaxation are included. The computational results show that oxygen dissociation is the dominant nonequilibrium flow phenomena affecting the optical distortion. However, as the freestream Mach number increases, atomic nitrogen begins to have an additional influence on optical aberrations.

@article{mackey2019b,
	title = {Assessment of {Hypersonic} {Flow} {Physics} on {Aero}-{Optics}},
	volume = {57},
	number = {9},
	journal = {AIAA Journal},
	author = {Mackey, Lauren E and Boyd, Iain D},
	month = sep,
	year = {2019},
	pages = {3885--3897},
}

@article{eyi2019b,
	title = {Aerothermodynamic {Design} {Optimization} of {Hypersonic} {Vehicles}},
	volume = {33},
	doi = {10.2514/1.T5523},
	abstract = {The objective of this study is to develop a reliable and efficient design optimization method for hypersonic vehicles focused on aerothermodynamic environments. Considering the nature of hypersonic flight, a high-fidelity aerothermodynamic analysis code is used for the simulation of weakly ionized hypersonic flows in thermochemical nonequilibrium. A gradient-based method is implemented for optimization. Bezier or nonuniform rational basis spline curves are used to parametrize the geometry or the geometry change. Linear elasticity theory is implemented for mesh deformation. Penalty functions are utilized to prevent undesired geometrical changes. The design objective is to minimize drag without increasing the total heat transfer rate and the maximum values of the surface heat flux, temperature, and pressure. Design optimizations are performed at different trajectory points of the IRV-2 vehicle. The effects of parametrizations, the number of design variables, and freestream conditions on design performance are studied.},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Eyi, Sinan and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2019},
	keywords = {own},
	pages = {392--406},
}

The objective of this study is to develop a reliable and efficient design optimization method for hypersonic vehicles focused on aerothermodynamic environments. Considering the nature of hypersonic flight, a high-fidelity aerothermodynamic analysis code is used for the simulation of weakly ionized hypersonic flows in thermochemical nonequilibrium. A gradient-based method is implemented for optimization. Bezier or nonuniform rational basis spline curves are used to parametrize the geometry or the geometry change. Linear elasticity theory is implemented for mesh deformation. Penalty functions are utilized to prevent undesired geometrical changes. The design objective is to minimize drag without increasing the total heat transfer rate and the maximum values of the surface heat flux, temperature, and pressure. Design optimizations are performed at different trajectory points of the IRV-2 vehicle. The effects of parametrizations, the number of design variables, and freestream conditions on design performance are studied.

@article{digiorgio2019,
	title = {An aerothermodynamic design optimization framework for hypersonic vehicles},
	volume = {84},
	doi = {10.1016/j.ast.2018.09.042},
	abstract = {In the aviation field great interest is growing in passengers transportation at hypersonic speed. This requires, however, careful study of the enabling technologies necessary for the optimal design of hypersonic vehicles. In this framework, the present work reports on a highly integrated design environment that has been developed in order to provide an optimization loop for vehicle aerothermodynamic design. It includes modules for geometrical parametrization, automated data transfer between tools, automated execution of computational analysis codes, and design optimization methods. This optimization environment is exploited for the aerodynamic design of an unmanned hypersonic cruiser flying at M∞=8 and 30 km altitude. The original contribution of this work is mainly found in the capability of the developed optimization environment of working simultaneously on shape and topology of the aircraft. The results reported and discussed highlight interesting design capabilities, and promise extension to more challenging and realistic integrated aerothermodynamic design problems.},
	journal = {Aerospace Science and Technology},
	author = {Di Giorgio, Simone and Quagliarella, Domenico and Pezzella, Giuseppe and Pirozzoli, Sergio},
	month = jan,
	year = {2019},
	note = {Publisher: Elsevier Masson SAS},
	keywords = {CST, Design optimization, Evolutionary strategies, Hypersonics},
	pages = {339--347},
}

In the aviation field great interest is growing in passengers transportation at hypersonic speed. This requires, however, careful study of the enabling technologies necessary for the optimal design of hypersonic vehicles. In this framework, the present work reports on a highly integrated design environment that has been developed in order to provide an optimization loop for vehicle aerothermodynamic design. It includes modules for geometrical parametrization, automated data transfer between tools, automated execution of computational analysis codes, and design optimization methods. This optimization environment is exploited for the aerodynamic design of an unmanned hypersonic cruiser flying at M∞=8 and 30 km altitude. The original contribution of this work is mainly found in the capability of the developed optimization environment of working simultaneously on shape and topology of the aircraft. The results reported and discussed highlight interesting design capabilities, and promise extension to more challenging and realistic integrated aerothermodynamic design problems.

@misc{hanquist2019,
	address = {Department of Aerospace \& Mechanical Engineering, University of Arizona},
	type = {Invited {Seminar}},
	title = {Aerothermodynamics of {Hypersonic} {Flight} and the {Importance} of {Modeling}},
	author = {Hanquist, Kyle M.},
	year = {2019},
	keywords = {invited, own},
}

@inproceedings{grover2019,
	title = {Ab {Initio} {Based} {Rate} {Coefficients} for {Two}-{Temperature} {Nonequilibrium} {Models} in {Hypersonic} {Blunt} {Body} {Flow}},
	publisher = {\{AIAA Paper\} 2019-0790},
	author = {Grover, Maninder S and Suchyta, Casimir J and Josyula, Eswar},
	year = {2019},
}

@article{mackey2019,
	title = {Aero-{Optical} {Assessments} of {Hypersonic} {Flowfields}},
	author = {Mackey, Lauren E},
	year = {2019},
}

@inproceedings{chen2019,
	title = {A chemical equilibrium analysis approach to oxidation and nitridation of silicon carbide},
	isbn = {978-1-62410-578-4},
	url = {https://arc.aiaa.org/doi/10.2514/6.2019-0243},
	doi = {10.2514/6.2019-0243},
	abstract = {Silicon carbide has unique oxidation properties that differ from those of ablative thermal protection materials, forming a stable oxide layer. A general thermodynamic equilibrium approach is presented for analysis of the oxidation and nitridation of silicon carbide, combining mass transport and multi-component equilibrium. Passive-to-active transitions are investigated in diluted oxygen, air, and nitrogen environments, and show good agreement with theory and experiments. Different passive-to-active transition mechanisms are examined for oxidation and nitridation, and oxidation exhibits a bifurcation between passive and active states. The thermodynamics leading to temperature jump are explained in the context of these results, and surface temperatures differ from experimental measurements in the literature to within 8\%.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Chen, Samuel Y. and Boyd, Iain D.},
	year = {2019},
}

Silicon carbide has unique oxidation properties that differ from those of ablative thermal protection materials, forming a stable oxide layer. A general thermodynamic equilibrium approach is presented for analysis of the oxidation and nitridation of silicon carbide, combining mass transport and multi-component equilibrium. Passive-to-active transitions are investigated in diluted oxygen, air, and nitrogen environments, and show good agreement with theory and experiments. Different passive-to-active transition mechanisms are examined for oxidation and nitridation, and oxidation exhibits a bifurcation between passive and active states. The thermodynamics leading to temperature jump are explained in the context of these results, and surface temperatures differ from experimental measurements in the literature to within 8%.

@article{birkan2019,
	title = {2019 {Electron} {Transpiration} {Cooling} of {Materials}},
	url = {https://community.apan.org/wg/afosr/w/researchareas/25542/2019-electron-transpiration-cooling-of-materials/},
	author = {Birkan, Mitat and Sayi, Ali and Leyva, Ivett and Uribarri, Luke},
	year = {2019},
	note = {Place: Washington, DC},
}

@inproceedings{andrienko2018,
	address = {Atlanta, GA},
	title = {Kinetics of {O}$_{\textrm{2}}$--{N}$_{\textrm{2}}$ collisions at hypersonic temperatures},
	publisher = {\{AIAA Paper\} 2018-3438},
	author = {Andrienko, Daniil A and Boyd, Iain D},
	month = jun,
	year = {2018},
}

@inproceedings{dalle2018,
	title = {Adjustments and {Uncertainty} {Quantification} for {SLS} {Aerodynamic} {Sectional} {Loads}},
	doi = {10.2514/6.2018-3640},
	booktitle = {{AIAA} {Aviation} {Forum}},
	author = {Dalle, Derek and Rogers, Stuart and Lee, Henry and Meeroff, Jamie},
	month = jun,
	year = {2018},
}

@inproceedings{tropina2018,
	address = {Atlanta, Georgia},
	title = {Aero-optical effects in non-equilibrium air},
	doi = {10.2514/6.2018-3904},
	publisher = {AIAA 2018-3904},
	author = {Tropina, Albina and Wu, Yue and Limbach, Christopher and Miles, Richard B},
	month = jun,
	year = {2018},
}

@article{huang2018,
	title = {Integrated {Aerothermoelastic} {Analysis} {Framework} with {Application} to {Skin} {Panels}},
	volume = {56},
	doi = {10.2514/1.J056677},
	abstract = {This study describes the development of an integrated aerothermoelastic computational framework. The framework consists of a Navier–Stokes aerodynamic solver based on an Automatic Differentiation flow solver code; a finite element structural solver for moderate deflection of a composite, doubly curved, shallow shell with thermal stress; and a finite element thermal solver for heat transfer in composite shallow shells with nonlinear material properties. The solvers are loosely coupled using a partitioned scheme. An analytical approach is developed to determine the time accuracy and the so-called energy accuracy of a loosely coupled scheme, which serves as a guide for designing schemes having a high convergence rate. The aeroelastic and aerothermoelastic behaviors of two-dimensional and three-dimensional panels are investigated using the computational framework. The effects of the aspect ratio and boundary-layer thickness are found to have significant influence on the critical flutter parameter and the onset time of aerothermoelastic instability.},
	number = {11},
	urldate = {2024-06-17},
	journal = {AIAA Journal},
	author = {Huang, Daning and Rokita, Tomer and Friedmann, Peretz P.},
	year = {2018},
	note = {Publisher: American Institute of Aeronautics and Astronautics
\_eprint: https://doi.org/10.2514/1.J056677},
	pages = {4562--4581},
}

This study describes the development of an integrated aerothermoelastic computational framework. The framework consists of a Navier–Stokes aerodynamic solver based on an Automatic Differentiation flow solver code; a finite element structural solver for moderate deflection of a composite, doubly curved, shallow shell with thermal stress; and a finite element thermal solver for heat transfer in composite shallow shells with nonlinear material properties. The solvers are loosely coupled using a partitioned scheme. An analytical approach is developed to determine the time accuracy and the so-called energy accuracy of a loosely coupled scheme, which serves as a guide for designing schemes having a high convergence rate. The aeroelastic and aerothermoelastic behaviors of two-dimensional and three-dimensional panels are investigated using the computational framework. The effects of the aspect ratio and boundary-layer thickness are found to have significant influence on the critical flutter parameter and the onset time of aerothermoelastic instability.

@article{alves2018,
	title = {Foundations of modelling of nonequilibrium low-temperature plasmas},
	volume = {27},
	issn = {0963-0252},
	url = {https://dx.doi.org/10.1088/1361-6595/aaa86d},
	doi = {10.1088/1361-6595/aaa86d},
	abstract = {This work explains the need for plasma models, introduces arguments for choosing the type of model that better fits the purpose of each study, and presents the basics of the most common nonequilibrium low-temperature plasma models and the information available from each one, along with an extensive list of references for complementary in-depth reading. The paper presents the following models, organised according to the level of multi-dimensional description of the plasma: kinetic models, based on either a statistical particle-in-cell/Monte-Carlo approach or the solution to the Boltzmann equation (in the latter case, special focus is given to the description of the electron kinetics); multi-fluid models, based on the solution to the hydrodynamic equations; global (spatially-average) models, based on the solution to the particle and energy rate-balance equations for the main plasma species, usually including a very complete reaction chemistry; mesoscopic models for plasma–surface interaction, adopting either a deterministic approach or a stochastic dynamical Monte-Carlo approach. For each plasma model, the paper puts forward the physics context, introduces the fundamental equations, presents advantages and limitations, also from a numerical perspective, and illustrates its application with some examples. Whenever pertinent, the interconnection between models is also discussed, in view of multi-scale hybrid approaches.},
	language = {en},
	number = {2},
	urldate = {2024-04-24},
	journal = {Plasma Sources Science and Technology},
	author = {Alves, L. L. and Bogaerts, A. and Guerra, V. and Turner, M. M.},
	month = feb,
	year = {2018},
	note = {Publisher: IOP Publishing},
	pages = {023002},
}

This work explains the need for plasma models, introduces arguments for choosing the type of model that better fits the purpose of each study, and presents the basics of the most common nonequilibrium low-temperature plasma models and the information available from each one, along with an extensive list of references for complementary in-depth reading. The paper presents the following models, organised according to the level of multi-dimensional description of the plasma: kinetic models, based on either a statistical particle-in-cell/Monte-Carlo approach or the solution to the Boltzmann equation (in the latter case, special focus is given to the description of the electron kinetics); multi-fluid models, based on the solution to the hydrodynamic equations; global (spatially-average) models, based on the solution to the particle and energy rate-balance equations for the main plasma species, usually including a very complete reaction chemistry; mesoscopic models for plasma–surface interaction, adopting either a deterministic approach or a stochastic dynamical Monte-Carlo approach. For each plasma model, the paper puts forward the physics context, introduces the fundamental equations, presents advantages and limitations, also from a numerical perspective, and illustrates its application with some examples. Whenever pertinent, the interconnection between models is also discussed, in view of multi-scale hybrid approaches.

@article{kraus2018,
	title = {Floating potential of emitting surfaces in plasmas with respect to the space potential},
	volume = {25},
	issn = {1070-664X, 1089-7674},
	doi = {10.1063/1.5018335},
	abstract = {The potential difference between a floating emitting surface and the plasma surrounding it has been described by several sheath models, including the space-charge-limited sheath, the electron sheath with high emission current, and the inverse sheath produced by charge-exchange ion trapping. Our measurements reveal that each of these models has its own regime of validity. We determine the potential of an emissive filament relative to the plasma potential, emphasizing variations in emitted current density and neutral particle density. The potential of a filament in a diffuse plasma is first shown to vanish, consistent with the electron sheath model and increasing electron emission. In a denser plasma with ample neutral pressure, the floating filament potential is positive, as predicted by a derived ion trapping condition. Lastly, the filament floated negatively in a third plasma, where flowing ions and electrons and nonnegligible electric fields may have disrupted ion trapping. Depending on the regime chosen, emitting surfaces can float positively or negatively with respect to the plasma potential.},
	language = {en},
	number = {3},
	urldate = {2024-01-24},
	journal = {Physics of Plasmas},
	author = {Kraus, B. F. and Raitses, Y.},
	month = mar,
	year = {2018},
}

The potential difference between a floating emitting surface and the plasma surrounding it has been described by several sheath models, including the space-charge-limited sheath, the electron sheath with high emission current, and the inverse sheath produced by charge-exchange ion trapping. Our measurements reveal that each of these models has its own regime of validity. We determine the potential of an emissive filament relative to the plasma potential, emphasizing variations in emitted current density and neutral particle density. The potential of a filament in a diffuse plasma is first shown to vanish, consistent with the electron sheath model and increasing electron emission. In a denser plasma with ample neutral pressure, the floating filament potential is positive, as predicted by a derived ion trapping condition. Lastly, the filament floated negatively in a third plasma, where flowing ions and electrons and nonnegligible electric fields may have disrupted ion trapping. Depending on the regime chosen, emitting surfaces can float positively or negatively with respect to the plasma potential.

@article{liu_laser_2018,
	title = {Laser additive manufacturing and homogeneous densification of complicated shape {SiC} ceramic parts},
	volume = {44},
	issn = {0272-8842},
	url = {https://www.sciencedirect.com/science/article/pii/S027288421832203X},
	doi = {10.1016/j.ceramint.2018.08.143},
	abstract = {To improve the density of SiC ceramic components with complicated shape built by laser sintering (LS), cold isostatic pressing (CIP) and reaction sintering (RS) were incorporated into the process. In the process of LS/CIP/RS, Phenol formaldehyde resin (PF)-SiC composite powder was prepared by mechanical mixing and cold coating methods, with an optimized content of PF at 18 wt\%. For the purpose of obtaining improved density of the sintered body after final reaction sintering, carbon black was added into the initial mixed powder. The material preparation, LS forming and densification steps were optimized throughout the whole fabrication process. The final sintered SiC bodies with the bending strength of 292 {\textasciitilde} 348 MPa and the density of 2.94–2.98 g cm− 3 were prepared using the PF coated SiC-C composite powder and the LS / CIP / RS process. The study further showed a positive and practical approach to fabricate SiC ceramic parts with complicated shape using additive manufacturing technology.},
	number = {17},
	urldate = {2023-10-28},
	journal = {Ceramics International},
	author = {Liu, Kai and Wu, Tian and Bourell, David L. and Tan, Yuanliang and Wang, Jiang and He, Mengqiang and Sun, Huajun and Shi, Yusheng and Chen, Jiaqi},
	month = dec,
	year = {2018},
	keywords = {A. Material preparation, B. Laser sintering, C. Cold isostatic pressing, D. Reaction sintering, E. Silicon carbide},
	pages = {21067--21075},
}

To improve the density of SiC ceramic components with complicated shape built by laser sintering (LS), cold isostatic pressing (CIP) and reaction sintering (RS) were incorporated into the process. In the process of LS/CIP/RS, Phenol formaldehyde resin (PF)-SiC composite powder was prepared by mechanical mixing and cold coating methods, with an optimized content of PF at 18 wt%. For the purpose of obtaining improved density of the sintered body after final reaction sintering, carbon black was added into the initial mixed powder. The material preparation, LS forming and densification steps were optimized throughout the whole fabrication process. The final sintered SiC bodies with the bending strength of 292 ~ 348 MPa and the density of 2.94–2.98 g cm− 3 were prepared using the PF coated SiC-C composite powder and the LS / CIP / RS process. The study further showed a positive and practical approach to fabricate SiC ceramic parts with complicated shape using additive manufacturing technology.

@article{carnevale2018,
	title = {Balancing {Work} and {Learning}},
	language = {en},
	author = {Carnevale, Anthony P and Smith, Nicole},
	year = {2018},
}

@article{patrick2018,
	title = {Predicting {Persistence} in {Engineering} through an {Engineering} {Identity} {Scale}},
	doi = {10.15781/T2ZC7SB9J},
	language = {en},
	urldate = {2023-09-08},
	author = {Patrick, A. and Borrego, M. and Prybutok, A.},
	year = {2018},
	note = {Publisher: International Journal of Engineering Education},
}

@article{sanchez2018,
	title = {Coupled adjoint-based sensitivities in large-displacement fluid-structure interaction using algorithmic differentiation: {Coupled} adjoint-based sensitivities in large-displacement fluid-structure interaction using algorithmic differentiation},
	volume = {113},
	issn = {00295981},
	shorttitle = {Coupled adjoint-based sensitivities in large-displacement fluid-structure interaction using algorithmic differentiation},
	doi = {10.1002/nme.5700},
	abstract = {A methodology for the calculation of gradients with respect to design parameters in general FluidStructure Interaction problems is presented. It is based on fixed-point iterations on the adjoint variables of the coupled system using Algorithmic Differentiation. This removes the need for the construction of the analytic Jacobian for the coupled physical problem, which is the usual limitation for the computation of adjoints in most realistic applications. The formulation is shown to be amenable to partitioned solution methods for the adjoint equations. It also poses no restrictions to the nonlinear physics in either the fluid or structural field, other than the existence of a converged solution to the primal problem from which to compute the adjoints. We demonstrate the applicability of this procedure and the accuracy of the computed gradients on coupled problems involving viscous flows with geometrical and material non-linearities in the structural domain.},
	language = {en},
	number = {7},
	urldate = {2023-08-07},
	journal = {International Journal for Numerical Methods in Engineering},
	author = {Sanchez, R. and Albring, T. and Palacios, R. and Gauger, N. R. and Economon, T. D. and Alonso, J. J.},
	month = feb,
	year = {2018},
	pages = {1081--1107},
}

A methodology for the calculation of gradients with respect to design parameters in general FluidStructure Interaction problems is presented. It is based on fixed-point iterations on the adjoint variables of the coupled system using Algorithmic Differentiation. This removes the need for the construction of the analytic Jacobian for the coupled physical problem, which is the usual limitation for the computation of adjoints in most realistic applications. The formulation is shown to be amenable to partitioned solution methods for the adjoint equations. It also poses no restrictions to the nonlinear physics in either the fluid or structural field, other than the existence of a converged solution to the primal problem from which to compute the adjoints. We demonstrate the applicability of this procedure and the accuracy of the computed gradients on coupled problems involving viscous flows with geometrical and material non-linearities in the structural domain.

@inproceedings{turbeville2018,
	address = {Atlanta, Georgia},
	title = {Boundary-{Layer} {Instability} on a {Slender} {Cone} with {Highly} {Swept} {Fins}},
	isbn = {978-1-62410-553-1},
	doi = {10.2514/6.2018-3070},
	language = {en},
	urldate = {2023-06-22},
	booktitle = {2018 {Fluid} {Dynamics} {Conference}},
	publisher = {American Institute of Aeronautics and Astronautics},
	author = {Turbeville, Franklin D. and Schneider, Steven P.},
	month = jun,
	year = {2018},
}

@article{bose2018,
	title = {Wall-{Modeled} {Large}-{Eddy} {Simulation} for {Complex} {Turbulent} {Flows}},
	volume = {50},
	issn = {0066-4189},
	doi = {10.1146/annurev-fluid-122316-045241},
	abstract = {Large-eddy simulation (LES) has proven to be a computationally tractable approach to simulate unsteady turbulent flows. However, prohibitive resolution requirements induced by near-wall eddies in high?Reynolds number boundary layers necessitate the use of wall models or approximate wall boundary conditions. We review recent investigations in wall-modeled LES, including the development of novel approximate boundary conditions and the application of wall models to complex flows (e.g., boundary-layer separation, shock/boundary-layer interactions, transition). We also assess the validity of underlying assumptions in wall-model derivations to elucidate the accuracy of these investigations, and offer suggestions for future studies.},
	number = {1},
	urldate = {2023-01-12},
	journal = {Annual Review of Fluid Mechanics},
	author = {Bose, Sanjeeb T. and Park, George Ilhwan},
	month = jan,
	year = {2018},
	note = {Publisher: Annual Reviews},
	pages = {535--561},
}

Large-eddy simulation (LES) has proven to be a computationally tractable approach to simulate unsteady turbulent flows. However, prohibitive resolution requirements induced by near-wall eddies in high?Reynolds number boundary layers necessitate the use of wall models or approximate wall boundary conditions. We review recent investigations in wall-modeled LES, including the development of novel approximate boundary conditions and the application of wall models to complex flows (e.g., boundary-layer separation, shock/boundary-layer interactions, transition). We also assess the validity of underlying assumptions in wall-model derivations to elucidate the accuracy of these investigations, and offer suggestions for future studies.

@inproceedings{mackey2018,
	title = {Turbulent hypersonic flow effects on optical sensor performance},
	isbn = {978-1-62410-553-1},
	url = {http://arc.aiaa.org},
	doi = {10.2514/6.2018-3712},
	abstract = {If an optical signal were to travel through a hypersonic flowfield, the type of high-speed flow analysis required to perform reliable assessments of sensor performance is unclear. In the present study, numerical simulations are utilized to perform implicit large eddy computations of a Mach 4 flow over an adiabatic flat plate. The simulations are run with and without thermochemistry models to determine the effects thermochemical nonequilibrium has on optical distortion. The higher fidelity simulation method of accounting for thermochemical nonequilibrium produces less variation in optical path difference (OPD) across the sensor aperture. The root mean square average of OPD is significantly smaller for the real gas simulation when compared to a perfect gas. These differences in OPD occur because nonequilibrium energy exchanges act to damp out turbulent fluctuations. It is, therefore, necessary to include these physical flow effects in optical assessments to obtain an accurate description of the aero-optic distortions.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Mackey, Lauren E. and Boyd, Iain D. and Jewell, Joseph S. and Leger, Timothy J.},
	year = {2018},
}

If an optical signal were to travel through a hypersonic flowfield, the type of high-speed flow analysis required to perform reliable assessments of sensor performance is unclear. In the present study, numerical simulations are utilized to perform implicit large eddy computations of a Mach 4 flow over an adiabatic flat plate. The simulations are run with and without thermochemistry models to determine the effects thermochemical nonequilibrium has on optical distortion. The higher fidelity simulation method of accounting for thermochemical nonequilibrium produces less variation in optical path difference (OPD) across the sensor aperture. The root mean square average of OPD is significantly smaller for the real gas simulation when compared to a perfect gas. These differences in OPD occur because nonequilibrium energy exchanges act to damp out turbulent fluctuations. It is, therefore, necessary to include these physical flow effects in optical assessments to obtain an accurate description of the aero-optic distortions.

@article{kim2018,
	title = {Thermochemical nonequilibrium parameter modification of oxygen for a two-temperature model},
	volume = {30},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.4996799},
	doi = {10.1063/1.4996799},
	abstract = {Thermochemical nonequilibrium parameters of oxygen, O2, for a two-temperature model are proposed in the present work. The rovibrational nonequilibrium and chemical reactions of three low-lying elec...},
	number = {1},
	journal = {Physics of Fluids},
	author = {Kim, Jae Gang and Park, Gisu},
	month = jan,
	year = {2018},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	keywords = {oxygen, pipe flow, rotational-vibrational states, shock tubes, shock waves, thermochemistry},
	pages = {016101--016101},
}

Thermochemical nonequilibrium parameters of oxygen, O2, for a two-temperature model are proposed in the present work. The rovibrational nonequilibrium and chemical reactions of three low-lying elec...

@article{hara2018,
	title = {Test cases for grid-based direct kinetic modeling of plasma flows},
	volume = {27},
	doi = {10.1088/1361-6595/aac6b9},
	abstract = {Grid-based kinetic models are promising in that the numerical noise inherent in particle-based methods is essentially eliminated. Here, we call such grid-based techniques a direct kinetic (DK) model. Velocity distribution functions are directly obtained by solving kinetic equations, such as the Vlasov equation, in discretized phase space, i.e., both physical and velocity space. In solving the kinetic equations that are hyperbolic partial differential equations, we employ a conservative, positivity-preserving numerical scheme, which is necessary for robust calculations of problems particularly including ionization. Test cases described in this paper include plasma sheaths with electron emission and injection and expansion of neutral atom flow in a two-dimensional configuration. A unifying kinetic theory of space charge limited sheaths for both floating and conducting surfaces is presented. The improved theory is verified using the collisionless DK simulation, particularly for small sheath potentials that particle-based kinetic simulations may struggle due to statistical noise. For benchmarking of the grid-based and particle-based kinetic simulations, hybrid simulations of Hall thruster discharge plasma are performed. While numerical diffusion occurs in the phase space in the DK simulation, ionization oscillations are well resolved since ionization events can be taken into account deterministically at every time step.},
	number = {6},
	journal = {Plasma Sources Science and Technology},
	author = {Hara, Kentaro and Hanquist, Kyle M.},
	year = {2018},
	keywords = {Hall thruster, Kinetic simulation, Vlasov simulation, etc, nonlinear plasma waves, own, plasma instability, plasma sheaths, space charge limited sheath},
}

Grid-based kinetic models are promising in that the numerical noise inherent in particle-based methods is essentially eliminated. Here, we call such grid-based techniques a direct kinetic (DK) model. Velocity distribution functions are directly obtained by solving kinetic equations, such as the Vlasov equation, in discretized phase space, i.e., both physical and velocity space. In solving the kinetic equations that are hyperbolic partial differential equations, we employ a conservative, positivity-preserving numerical scheme, which is necessary for robust calculations of problems particularly including ionization. Test cases described in this paper include plasma sheaths with electron emission and injection and expansion of neutral atom flow in a two-dimensional configuration. A unifying kinetic theory of space charge limited sheaths for both floating and conducting surfaces is presented. The improved theory is verified using the collisionless DK simulation, particularly for small sheath potentials that particle-based kinetic simulations may struggle due to statistical noise. For benchmarking of the grid-based and particle-based kinetic simulations, hybrid simulations of Hall thruster discharge plasma are performed. While numerical diffusion occurs in the phase space in the DK simulation, ionization oscillations are well resolved since ionization events can be taken into account deterministically at every time step.

@article{witze2018,
	title = {The {Quest} to {Conquer} the {Space} {Junk} {Problem}},
	volume = {561},
	journal = {Nature},
	author = {Witze, Alexandra},
	year = {2018},
}

@article{molchanova2018,
	title = {Surface recombination in the direct simulation {Monte} {Carlo} method},
	volume = {30},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.5048353},
	doi = {10.1063/1.5048353},
	abstract = {This work is aimed at the development of surface chemistry models for the Direct Simulation Monte Carlo (DSMC) method applicable to non-equilibrium high-temperature flows about reentry vehicles. Pr...},
	number = {10},
	journal = {Physics of Fluids},
	author = {Molchanova, Alexandra N. and Kashkovsky, Alexander V. and Bondar, Yevgeniy A.},
	month = oct,
	year = {2018},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	pages = {107105--107105},
}

This work is aimed at the development of surface chemistry models for the Direct Simulation Monte Carlo (DSMC) method applicable to non-equilibrium high-temperature flows about reentry vehicles. Pr...

@article{chaudhry2018a,
	title = {Quasiclassical trajectory analysis of nitrogen for high-temperature chemical kinetics},
	volume = {32},
	url = {https://arc.aiaa.org/doi/10.2514/1.T5484},
	doi = {10.2514/1.T5484/ASSET/IMAGES/LARGE/FIGURE12.JPEG},
	abstract = {Understanding gas–phase chemical kinetics is important for modeling hypersonic flows. This paper discusses quasiclassical trajectory analysis, in which gas–phase interactions are simulated using ab initio quantum chemistry data. N2 N2, N2 N, and N2 O2 collisions are studied for conditions at thermal equilibrium and nonequilibrium. The nitrogen dissociation rate with all collision partners is found to be similar for a given thermal environment: the largest deviation is 50\% at thermal nonequilibrium, and at equilibrium the N2 N2 and N2 N rates are within 15\% of each other. The vibrational energy decrease due to nitrogen dissociation, a necessary input to computational fluid dynamics, also behaves similarly for all collision partners and strongly depends on the degree of thermal nonequilibrium. Using data for nitrogen dissociation and oxygen dissociation with partner N2, the effect of each reactant state on dissociation is quantified. The effect of the collision partner’s internal energy on simple dissociation is found to be small and likely negligible. Finally, the effect of vibrational energy on simple dissociation is found to be stronger than the effect of rotational energy. These rigorous statistical analyses enable the development of physics-based models for computational fluid dynamics.},
	number = {4},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Chaudhry, Ross S. and Bender, Jason D. and Schwartzentruber, Thomas E. and Candler, Graham V.},
	month = sep,
	year = {2018},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Boltzmann Constant, Born Oppenheimer Approximation, CFD, Energy Distribution, High Temperature Chemical Kinetics, Hypersonic Flows, Internal Energy, Probability Density Functions, Shock Tube, Thermal Nonequilibrium},
	pages = {833--845},
}

Understanding gas–phase chemical kinetics is important for modeling hypersonic flows. This paper discusses quasiclassical trajectory analysis, in which gas–phase interactions are simulated using ab initio quantum chemistry data. N2 N2, N2 N, and N2 O2 collisions are studied for conditions at thermal equilibrium and nonequilibrium. The nitrogen dissociation rate with all collision partners is found to be similar for a given thermal environment: the largest deviation is 50% at thermal nonequilibrium, and at equilibrium the N2 N2 and N2 N rates are within 15% of each other. The vibrational energy decrease due to nitrogen dissociation, a necessary input to computational fluid dynamics, also behaves similarly for all collision partners and strongly depends on the degree of thermal nonequilibrium. Using data for nitrogen dissociation and oxygen dissociation with partner N2, the effect of each reactant state on dissociation is quantified. The effect of the collision partner’s internal energy on simple dissociation is found to be small and likely negligible. Finally, the effect of vibrational energy on simple dissociation is found to be stronger than the effect of rotational energy. These rigorous statistical analyses enable the development of physics-based models for computational fluid dynamics.

@article{tumuklu2018a,
	title = {On the unsteadiness of shock–laminar boundary layer interactions of hypersonic flows over a double cone},
	volume = {30},
	issn = {1070-6631, 1089-7666},
	doi = {10.1063/1.5047791},
	language = {en},
	number = {10},
	urldate = {2023-05-12},
	journal = {Physics of Fluids},
	author = {Tumuklu, Ozgur and Theofilis, Vassilis and Levin, Deborah A.},
	month = oct,
	year = {2018},
}

@inproceedings{hanquist2018g,
	title = {Modeling of {Excited} {Oxygen} in {Post} {Normal} {Shock} {Waves}},
	doi = {10.2514/6.2018-3769},
	abstract = {The successful development of hypersonic vehicles requires a detailed knowledge of the flow physics around the vehicle. Specifically, an understanding of the thermochemical nonequilibrium behavior is crucial for this flight regime. The hypersonic flight regime involves an extremely high level of energy, so a small error in the modeling of the energy processes can result in drastic changes in the vehicle design, which motivates modeling the physics involved at a high-fidelity. Recent progress is presented in an ongoing effort to model the excited states of oxygen in post-normal shock waves using computational fluid dynamics. One-dimensional post normal shock flow calculations are carried out using state-of-the-art thermochemical nonequilibrium models. Two-temperature and electronic master equation coupling models are adopted in the present work and discussed in detail. Different approaches of modeling the energy transfer from each mode are also presented. The approaches are assessed using a set of existing experiments where the vibrational temperature was measured. The concentrations of excited states of atomic oxygen determined by the electronic master equation coupling model are compared to Boltzmann distributions.},
	booktitle = {2018 {Joint} {Thermophysics} and {Heat} {Transfer} {Conference}},
	publisher = {AIAA Paper 2018-3769},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2018},
	keywords = {own},
}

The successful development of hypersonic vehicles requires a detailed knowledge of the flow physics around the vehicle. Specifically, an understanding of the thermochemical nonequilibrium behavior is crucial for this flight regime. The hypersonic flight regime involves an extremely high level of energy, so a small error in the modeling of the energy processes can result in drastic changes in the vehicle design, which motivates modeling the physics involved at a high-fidelity. Recent progress is presented in an ongoing effort to model the excited states of oxygen in post-normal shock waves using computational fluid dynamics. One-dimensional post normal shock flow calculations are carried out using state-of-the-art thermochemical nonequilibrium models. Two-temperature and electronic master equation coupling models are adopted in the present work and discussed in detail. Different approaches of modeling the energy transfer from each mode are also presented. The approaches are assessed using a set of existing experiments where the vibrational temperature was measured. The concentrations of excited states of atomic oxygen determined by the electronic master equation coupling model are compared to Boltzmann distributions.

@article{chaudhry2018,
	title = {Modeling and {Analysis} of {Chemical} {Kinetics} for {Hypersonic} {Flows} in {Air}},
	author = {Chaudhry, Ross S},
	year = {2018},
}

@inproceedings{parent2018,
	title = {Large {Eddy} {Simulation} of {Boundary} {Layer} {Transition} {Induced} by {DBD} {Plasma} {Actuators}},
	doi = {10.2514/6.2018-0444},
	abstract = {Nomenclature Roman symbols C k = particule charge of kth species, C E = electric field vector, r , V/m n s = number of species (including charged species) N k = species number density, m 3 P k = species partial pressure, Pa P = pressure of mixture, Pa s k = sign of the charge of species k (either C1 for the positive species or 1 for the negative species) T = temperature of mixture, K t = time, s U = flow speed, m/s V n = velocity of the neutrals, m/s x i = Cartesian coordinates, m x; y; z = Cartesian coordinates, m Greek symbols 0 = permittivity of free space, m 3 kg 1 s 4 A 2 r = relative permittivity = conductivity, S/m = electric field potential, V c = net charge density, C m 3 k = mobility of kth species, m 2 /(V s) Subscripts w = at the wall 1 = free stream},
	author = {Parent, Bernard and Shneider, Mikhail N and Macheret, Sergey O},
	year = {2018},
}

Nomenclature Roman symbols C k = particule charge of kth species, C E = electric field vector, r , V/m n s = number of species (including charged species) N k = species number density, m 3 P k = species partial pressure, Pa P = pressure of mixture, Pa s k = sign of the charge of species k (either C1 for the positive species or 1 for the negative species) T = temperature of mixture, K t = time, s U = flow speed, m/s V n = velocity of the neutrals, m/s x i = Cartesian coordinates, m x; y; z = Cartesian coordinates, m Greek symbols 0 = permittivity of free space, m 3 kg 1 s 4 A 2 r = relative permittivity = conductivity, S/m = electric field potential, V c = net charge density, C m 3 k = mobility of kth species, m 2 /(V s) Subscripts w = at the wall 1 = free stream

@article{tumuklu2018,
	title = {Investigation of unsteady, hypersonic, laminar separated flows over a double cone geometry using a kinetic approach},
	volume = {30},
	issn = {1070-6631, 1089-7666},
	doi = {10.1063/1.5022598},
	language = {en},
	number = {4},
	urldate = {2023-05-12},
	journal = {Physics of Fluids},
	author = {Tumuklu, Ozgur and Levin, Deborah A. and Theofilis, Vassilis},
	year = {2018},
}

@inproceedings{bhattrai2018,
	title = {Influence of hypersonic fluid-structure interaction on the control authority of a trailing-edge flap},
	url = {http://arc.aiaa.org},
	doi = {10.2514/6.2018-5265},
	abstract = {This paper describes the numerical and experimental investigation of rigid and compliant hypersonic control flaps undergoing fluid-structure interaction (FSI). The purpose of the study is to investigate experimental techniques that support the evaluation of flight control systems in hypersonic ground test-with the emphasis of providing control to a trailing-edge flap model undergoing FSI. The rigid flap and compliant flap (of 1 mm thickness) were tested at inclination angles of 0 • , 5 • , 10 • , 15 • , and 20 •. Numerical simulations of two-and three-dimensional flow fields were carried-out in US3D, while the experiments were conducted at the University of Southern Queensland hypersonic wind tunnel facility (TUSQ), under the test flow conditions of Mach 5.8, 75 K and 755 Pa. The forces and moments acting on the models-primarily the lift, drag and pitching moment-were measured with a six component load cell. Tests were carried-out both with and without the load cell to observe the models' responses independently. The schlieren method was used to visualize the flow fields. The schlieren images were also used to obtain the flap deformation profile, as well as, the flap trailing-edge oscillation response. Frequency analysis of the complaint flaps was performed with the load cell measurement responses of lift, drag and pitching moment, and schlieren-tracked response of the flap trailing-edge. From the analyses, the load cell was found to have a low-frequency response of its own. In absence of the load cell, the compliant flap trailing-edge oscillation induced a new structural vibration mode that lead to a destructive interference of the oscillation. While, in the presence of the load cell, it's low-rigidity had the effect of damping this induced vibration. The data and analysis presented in this study are also used in designing the future experiments that will implement a software-in-the-loop actuated control of the rigid and compliant flap models.},
	author = {Bhattrai, Sudip and Mcquellin, Liam P and Currao, Gaetano M D and Neely, Andrew J and Buttsworth, David R},
	year = {2018},
}

This paper describes the numerical and experimental investigation of rigid and compliant hypersonic control flaps undergoing fluid-structure interaction (FSI). The purpose of the study is to investigate experimental techniques that support the evaluation of flight control systems in hypersonic ground test-with the emphasis of providing control to a trailing-edge flap model undergoing FSI. The rigid flap and compliant flap (of 1 mm thickness) were tested at inclination angles of 0 • , 5 • , 10 • , 15 • , and 20 •. Numerical simulations of two-and three-dimensional flow fields were carried-out in US3D, while the experiments were conducted at the University of Southern Queensland hypersonic wind tunnel facility (TUSQ), under the test flow conditions of Mach 5.8, 75 K and 755 Pa. The forces and moments acting on the models-primarily the lift, drag and pitching moment-were measured with a six component load cell. Tests were carried-out both with and without the load cell to observe the models' responses independently. The schlieren method was used to visualize the flow fields. The schlieren images were also used to obtain the flap deformation profile, as well as, the flap trailing-edge oscillation response. Frequency analysis of the complaint flaps was performed with the load cell measurement responses of lift, drag and pitching moment, and schlieren-tracked response of the flap trailing-edge. From the analyses, the load cell was found to have a low-frequency response of its own. In absence of the load cell, the compliant flap trailing-edge oscillation induced a new structural vibration mode that lead to a destructive interference of the oscillation. While, in the presence of the load cell, it's low-rigidity had the effect of damping this induced vibration. The data and analysis presented in this study are also used in designing the future experiments that will implement a software-in-the-loop actuated control of the rigid and compliant flap models.

@inproceedings{hanquist2018e,
	title = {Effectiveness of {Thermionic} {Emission} for {Cooling} {Hypersonic} {Vehicle} {Surfaces}},
	doi = {10.2514/6.2018-1714},
	abstract = {Electron transpiration cooling (ETC) is a proposed thermal management approach for the leading edges of hypersonic vehicles that utilizes thermionic emission to emit electrons to carry heat away from the surface. This paper presents a modeling approach for implementing ETC in a computational fluid dynamics (CFD) framework and assesses the modeling approach using a set of previously completed experiments. The modeling approach includes coupling the fluid modeling to a material response code to model in-depth surface conduction and accounts for space-charge-limited emission. The effectiveness of ETC for multiple test cases are investigated including a case with a sharp leading edge, case with in-depth material conduction, and a blunt body (i.e. capsule). For each of these test cases, ETC affects the surface properties, most notably the surface temperature, suggesting that ETC occurs for bodies in thermally intense, ionized flows, no matter the shape of the leading edge. An equation is provided to estimate the heat transfer induced by ETC.},
	booktitle = {{AIAA} {SCITECH} 2018 {Forum}},
	publisher = {AIAA Paper 2018-1714},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2018},
	keywords = {etc, own},
}

Electron transpiration cooling (ETC) is a proposed thermal management approach for the leading edges of hypersonic vehicles that utilizes thermionic emission to emit electrons to carry heat away from the surface. This paper presents a modeling approach for implementing ETC in a computational fluid dynamics (CFD) framework and assesses the modeling approach using a set of previously completed experiments. The modeling approach includes coupling the fluid modeling to a material response code to model in-depth surface conduction and accounts for space-charge-limited emission. The effectiveness of ETC for multiple test cases are investigated including a case with a sharp leading edge, case with in-depth material conduction, and a blunt body (i.e. capsule). For each of these test cases, ETC affects the surface properties, most notably the surface temperature, suggesting that ETC occurs for bodies in thermally intense, ionized flows, no matter the shape of the leading edge. An equation is provided to estimate the heat transfer induced by ETC.

@article{manohar2018,
	title = {Data-{Driven} {Sparse} {Sensor} {Placement} for {Reconstruction}: {Demonstrating} the {Benefits} of {Exploiting} {Known} {Patterns}},
	volume = {38},
	doi = {10.1109/MCS.2018.2810460},
	abstract = {Optimal sensor and actuator placement is an important unsolved problem in control theory. Nearly every downstream control decision is affected by these sensor and actuator locations, but determining optimal locations amounts to an intractable brute-force search among the combinatorial possibilities. Indeed, there are (np) = n!/((n-p)!p!) possible choices of p point sensors out of an n-dimensional state x. Determining optimal sensor and actuator placement in general, even for linear feedback control, is an open challenge. Instead, sensor and actuator locations are routinely chosen according to heuristics and intuition. For moderate-sized search spaces, the sensor placement problem has well-known model-based solutions using optimal experiment design [1], [2], and information theoretic and Bayesian criteria [3]-[7]. As discussed in »Summary,» this article explores how to design optimal sensor locations for signal reconstruction in a framework that scales to arbitrarily large problems, leveraging modern techniques in machine learning and sparse sampling. Reducing the number of sensors through principled selection may be critically enabling when sensors are costly, and it may also enable faster state estimation for low-latency, high-bandwidth control.},
	number = {3},
	journal = {IEEE Control Systems},
	author = {Manohar, Krithika and Brunton, Bingni W. and Kutz, J. Nathan and Brunton, Steven L.},
	month = jun,
	year = {2018},
	note = {Publisher: Institute of Electrical and Electronics Engineers Inc.},
	pages = {63--86},
}

Optimal sensor and actuator placement is an important unsolved problem in control theory. Nearly every downstream control decision is affected by these sensor and actuator locations, but determining optimal locations amounts to an intractable brute-force search among the combinatorial possibilities. Indeed, there are (np) = n!/((n-p)!p!) possible choices of p point sensors out of an n-dimensional state x. Determining optimal sensor and actuator placement in general, even for linear feedback control, is an open challenge. Instead, sensor and actuator locations are routinely chosen according to heuristics and intuition. For moderate-sized search spaces, the sensor placement problem has well-known model-based solutions using optimal experiment design [1], [2], and information theoretic and Bayesian criteria [3]-[7]. As discussed in »Summary,» this article explores how to design optimal sensor locations for signal reconstruction in a framework that scales to arbitrarily large problems, leveraging modern techniques in machine learning and sparse sampling. Reducing the number of sensors through principled selection may be critically enabling when sensors are costly, and it may also enable faster state estimation for low-latency, high-bandwidth control.

@article{jaffe2018,
	title = {Comparison of potential energy surface and computed rate coefficients for {N2} dissociation},
	volume = {32},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.T5417},
	doi = {10.2514/1.T5417},
	abstract = {Comparisons are made between potential energy surfaces (PESs) for N2 N and N2 N2 collisions and between rate coefficients for N2 dissociation that were computed using the quasi-classical trajectory (QCT) method on these PESs. For N2 N, Laganà’s empirical London–Eyring–Polanyi–Sato surface is compared with one from NASA Ames Research Center based on ab initio quantum chemistry calculations. For N2 N2, two ab initio PESs (from NASA Ames and from the University of Minnesota) are compared. These use different methods for computing the ground state electronic energy for N4 but give similar results. Thermal N2 dissociation rate coefficients, for the 10,000–30,000 K temperature range, have been computed using each PES, and the results are in excellent agreement. Quasi-stationary state (QSS) rate coefficients using both PESs have been computed at these temperatures using the direct molecular simulation method (DMS) of Schwartzentruber and coworkers. The QSS rate coefficients are up to a factor of 5 lower than the thermal ones, and the thermal and QSS values bracket the results of shock-tube experiments. It is concluded that the combination of ab initio quantum chemistry PESs and QCT calculations provides an attractive approach for the determination of accurate high-temperature rate coefficients for use in aerothermodynamics modeling.},
	number = {4},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Jaffe, Richard L. and Grover, Maninder and Venturi, Simone and Schwenke, David W. and Valentini, Paolo and Schwartzentruber, Thomas E. and Panesi, Marco},
	month = sep,
	year = {2018},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Aerothermodynamics, CFD, Classical Mechanics, Computing, Direct Simulation Monte Carlo, Energy Distribution, NASA Ames Research Center, Schrodinger Equation, Shock Tube, Thermal Nonequilibrium},
	pages = {869--881},
}

Comparisons are made between potential energy surfaces (PESs) for N2 N and N2 N2 collisions and between rate coefficients for N2 dissociation that were computed using the quasi-classical trajectory (QCT) method on these PESs. For N2 N, Laganà’s empirical London–Eyring–Polanyi–Sato surface is compared with one from NASA Ames Research Center based on ab initio quantum chemistry calculations. For N2 N2, two ab initio PESs (from NASA Ames and from the University of Minnesota) are compared. These use different methods for computing the ground state electronic energy for N4 but give similar results. Thermal N2 dissociation rate coefficients, for the 10,000–30,000 K temperature range, have been computed using each PES, and the results are in excellent agreement. Quasi-stationary state (QSS) rate coefficients using both PESs have been computed at these temperatures using the direct molecular simulation method (DMS) of Schwartzentruber and coworkers. The QSS rate coefficients are up to a factor of 5 lower than the thermal ones, and the thermal and QSS values bracket the results of shock-tube experiments. It is concluded that the combination of ab initio quantum chemistry PESs and QCT calculations provides an attractive approach for the determination of accurate high-temperature rate coefficients for use in aerothermodynamics modeling.

@inproceedings{mbagwu2018,
	title = {An examination of vehicle design tradeoffs and trajectory optimization for trimmed scramjet-powered hypersonic vehicles on ascent},
	isbn = {978-1-62410-532-6},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2018-0417},
	doi = {10.2514/6.2018-0417},
	abstract = {Several design rules are discussed that can be helpful in optimizing the design and the ascent trajectory of a generic hypersonic vehicle that is powered by a dual-mode ramjet-scramjet engine. The focus is on “vehicle integration” design rules, which differ from the “propulsion-oriented” optimization that has been discussed in certain textbooks. Vehicle-integration rules account for realistic constraints, including the requirement that the vehicle must be trimmed at all points along an ascent trajectory and that additive drag and vehicle stability are considered. A hypersonic waverider does not follow rules for a conventional airplane, where the goal is a large ratio of wing area to frontal area in order to maximize Lift/Drag ratio. Nor does a waverider follow rules for a rocket (where the goal is to maximize the Thrust/Drag ratio, requiring a small ratio of wing area to frontal area). Instead a waverider requires an optimization of both T/D and L/D, which introduces certain challenges. Governing parameters that were varied were: aspect ratio (b/c), engine inlet width (W), root chord length (c), acceleration profiles (a), and flight Mach number (M). The output parameters selected for optimization were thrust-to-drag (T/D) and lift-to-drag (L/D). Trends for auxiliary parameters such as angle-of-attack (α), elevon deflection angle (δ), and equivalence ratio (φ) were examined. A surrogate-based optimization algorithm was applied. The advantages of selecting the largest possible dynamic pressure are discussed. Trajectory optimization was also performed to minimize fuel burn mf and maximize (T/D) along an ascent trajectory.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Mbagwu, Chukwuka C. and Driscoll, James F.},
	year = {2018},
	note = {Issue: 210049},
}

Several design rules are discussed that can be helpful in optimizing the design and the ascent trajectory of a generic hypersonic vehicle that is powered by a dual-mode ramjet-scramjet engine. The focus is on “vehicle integration” design rules, which differ from the “propulsion-oriented” optimization that has been discussed in certain textbooks. Vehicle-integration rules account for realistic constraints, including the requirement that the vehicle must be trimmed at all points along an ascent trajectory and that additive drag and vehicle stability are considered. A hypersonic waverider does not follow rules for a conventional airplane, where the goal is a large ratio of wing area to frontal area in order to maximize Lift/Drag ratio. Nor does a waverider follow rules for a rocket (where the goal is to maximize the Thrust/Drag ratio, requiring a small ratio of wing area to frontal area). Instead a waverider requires an optimization of both T/D and L/D, which introduces certain challenges. Governing parameters that were varied were: aspect ratio (b/c), engine inlet width (W), root chord length (c), acceleration profiles (a), and flight Mach number (M). The output parameters selected for optimization were thrust-to-drag (T/D) and lift-to-drag (L/D). Trends for auxiliary parameters such as angle-of-attack (α), elevon deflection angle (δ), and equivalence ratio (φ) were examined. A surrogate-based optimization algorithm was applied. The advantages of selecting the largest possible dynamic pressure are discussed. Trajectory optimization was also performed to minimize fuel burn mf and maximize (T/D) along an ascent trajectory.

@inproceedings{eyi2018b,
	title = {Aerothermodynamic {Design} {Optimization} of {Hypersonic} {Vehicles}},
	doi = {10.2514/6.2018-3108},
	abstract = {The objective of this study is to develop a reliable and efficient design optimization method for hypersonic vehicles focused on aerothermodynamics. Considering the nature of hypersonic flight, a high-fidelity aerothermodynamic analysis code is utilized for the simulation of weakly ionized hypersonic flows in thermo-chemical non-equilibrium. A gradient-based method is implemented for optimization. Bezier or NURBS curves are used to parametrize the geometry or the geometry change. Linear elasticity theory is implemented for mesh deformation. Penalty functions are utilized to prevent undesired geometrical changes. The design objective is to minimize drag without increasing the heat transfer rate and the maximum values of the surface heat flux, temperature and pressure. Design optimizations are performed at different trajectory points of the IRV-2 vehicle. The effects of parametrizations, the number of design variables and freestream conditions on design performance are studied.},
	booktitle = {2018 {Multidisciplinary} {Analysis} and {Optimization} {Conference}},
	publisher = {AIAA Paper 2018-3108},
	author = {Eyi, Sinan and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2018},
	keywords = {own},
}

The objective of this study is to develop a reliable and efficient design optimization method for hypersonic vehicles focused on aerothermodynamics. Considering the nature of hypersonic flight, a high-fidelity aerothermodynamic analysis code is utilized for the simulation of weakly ionized hypersonic flows in thermo-chemical non-equilibrium. A gradient-based method is implemented for optimization. Bezier or NURBS curves are used to parametrize the geometry or the geometry change. Linear elasticity theory is implemented for mesh deformation. Penalty functions are utilized to prevent undesired geometrical changes. The design objective is to minimize drag without increasing the heat transfer rate and the maximum values of the surface heat flux, temperature and pressure. Design optimizations are performed at different trajectory points of the IRV-2 vehicle. The effects of parametrizations, the number of design variables and freestream conditions on design performance are studied.

@article{campanell2018,
	title = {Alternative model of space-charge-limited thermionic current flow through a plasma},
	volume = {97},
	doi = {10.1103/PhysRevE.97.043207},
	abstract = {It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge-limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate a fundamentally different current-limited mode. In the "inverse" mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting the circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. The inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.},
	journal = {Physical Review E},
	author = {Campanell, M D},
	year = {2018},
	keywords = {doi:10.1103/PhysRevE.97.043207 url:https://doi.org},
	pages = {1--16},
}

It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge-limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate a fundamentally different current-limited mode. In the "inverse" mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting the circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. The inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.

@article{andrienko2017,
	title = {State-specific dissociation in {O}$_{\textrm{2}}$-{O}$_{\textrm{2}}$ collisions by quasiclassical trajectory method},
	volume = {491},
	doi = {10.1016/j.chemphys.2017.05.005},
	journal = {Chemical Physics},
	author = {Andrienko, D A and Boyd, I D},
	year = {2017},
	pages = {74--81},
}

@article{herrera-montojo2017,
	title = {Shock-conforming mesh generation for aerodynamic analyses at supersonic regimes},
	volume = {157},
	doi = {https://doi.org/10.1016},
	journal = {Computers \& Fluids},
	author = {Herrera-Montojo, J. and Fossati, M. and Minisci, E.},
	month = nov,
	year = {2017},
	pages = {276--293},
}

@inproceedings{molina2017,
	address = {Denver, Colorado},
	title = {Hybrid {RANS}/{LES} {Calculations} in {SU2}},
	isbn = {978-1-62410-506-7},
	doi = {10.2514/6.2017-4284},
	language = {en},
	urldate = {2023-01-12},
	booktitle = {23rd {AIAA} {Computational} {Fluid} {Dynamics} {Conference}},
	publisher = {AIAA Paper 2017-4284},
	author = {Molina, Eduardo and Spode, Cleber and Annes da Silva, Roberto G. and Manosalvas-Kjono, David E. and Nimmagadda, Sravya and Economon, Thomas D. and Alonso, Juan J. and Righi, Marcello},
	year = {2017},
}

@inproceedings{tulp2017,
	title = {Rocket {Lab}: {Liberating} the {Small} {Satellite} {Market}},
	publisher = {AIAA},
	author = {Tulp, Jessica and Beck, Peter},
	year = {2017},
}

@book{griffiths2017,
	title = {Introduction to {Electrodynamics}},
	isbn = {978-1-108-33351-1},
	publisher = {Cambridge University Press},
	author = {Griffiths, David J.},
	year = {2017},
}

@article{mortari2017a,
	title = {Least-{Squares} {Solution} of {Linear} {Differential} {Equations}},
	volume = {5},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	issn = {2227-7390},
	url = {https://www.mdpi.com/2227-7390/5/4/48},
	doi = {10.3390/math5040048},
	abstract = {This study shows how to obtain least-squares solutions to initial value problems (IVPs), boundary value problems (BVPs), and multi-value problems (MVPs) for nonhomogeneous linear differential equations (DEs) with nonconstant coefficients of any order. However, without loss of generality, the approach has been applied to second-order DEs. The proposed method has two steps. The first step consists of writing a constrained expression, that has the DE constraints embedded. These kind of expressions are given in terms of a new unknown function,     g ( t )    , and they satisfy the constraints, no matter what     g ( t )     is. The second step consists of expressing     g ( t )     as a linear combination of m independent known basis functions. Specifically, orthogonal polynomials are adopted for the basis functions. This choice requires rewriting the DE and the constraints in terms of a new independent variable,     x ∈ [ − 1 , + 1 ]    . The procedure leads to a set of linear equations in terms of the unknown coefficients of the basis functions that are then computed by least-squares. Numerical examples are provided to quantify the solutions’ accuracy for IVPs, BVPs and MVPs. In all the examples provided, the least-squares solution is obtained with machine error accuracy.},
	language = {en},
	number = {4},
	urldate = {2024-04-24},
	journal = {Mathematics},
	author = {Mortari, Daniele},
	month = dec,
	year = {2017},
	keywords = {embedded linear constraints, interpolation, linear least-squares},
	pages = {48},
}

This study shows how to obtain least-squares solutions to initial value problems (IVPs), boundary value problems (BVPs), and multi-value problems (MVPs) for nonhomogeneous linear differential equations (DEs) with nonconstant coefficients of any order. However, without loss of generality, the approach has been applied to second-order DEs. The proposed method has two steps. The first step consists of writing a constrained expression, that has the DE constraints embedded. These kind of expressions are given in terms of a new unknown function, g ( t ) , and they satisfy the constraints, no matter what g ( t ) is. The second step consists of expressing g ( t ) as a linear combination of m independent known basis functions. Specifically, orthogonal polynomials are adopted for the basis functions. This choice requires rewriting the DE and the constraints in terms of a new independent variable, x ∈ [ − 1 , + 1 ] . The procedure leads to a set of linear equations in terms of the unknown coefficients of the basis functions that are then computed by least-squares. Numerical examples are provided to quantify the solutions’ accuracy for IVPs, BVPs and MVPs. In all the examples provided, the least-squares solution is obtained with machine error accuracy.

@article{mortari2017,
	title = {The theory of connections: {Connecting} points},
	volume = {5},
	issn = {2227-7390},
	doi = {10.3390/math5040057},
	abstract = {This study introduces a procedure to obtain all interpolating functions, y = f ( x ) , subject to linear constraints on the function and its derivatives defined at specified values. The paper first shows how to express these interpolating functions passing through a single point in three distinct ways: linear, additive, and rational. Then, using the additive formalism, interpolating functions with linear constraints on one, two, and n points are introduced as well as those satisfying relative constraints. In particular, for expressions passing through n points, a generalization of the Waring’s interpolation form is introduced. An alternative approach to derive additive constraint interpolating expressions is introduced requiring the inversion of a matrix with dimensions equally the number of constraints. Finally, continuous and discontinuous interpolating periodic functions passing through a set of points with specified periods are provided. This theory has already been applied to obtain least-squares solutions of initial and boundary value problems applied to nonhomogeneous linear differential equations with nonconstant coefficients.},
	number = {4},
	journal = {Mathematics},
	author = {Mortari, Daniele},
	year = {2017},
	note = {Number: 57},
}

This study introduces a procedure to obtain all interpolating functions, y = f ( x ) , subject to linear constraints on the function and its derivatives defined at specified values. The paper first shows how to express these interpolating functions passing through a single point in three distinct ways: linear, additive, and rational. Then, using the additive formalism, interpolating functions with linear constraints on one, two, and n points are introduced as well as those satisfying relative constraints. In particular, for expressions passing through n points, a generalization of the Waring’s interpolation form is introduced. An alternative approach to derive additive constraint interpolating expressions is introduced requiring the inversion of a matrix with dimensions equally the number of constraints. Finally, continuous and discontinuous interpolating periodic functions passing through a set of points with specified periods are provided. This theory has already been applied to obtain least-squares solutions of initial and boundary value problems applied to nonhomogeneous linear differential equations with nonconstant coefficients.

@article{li2017,
	title = {Thermal–stress analysis on the crack formation of tungsten during fusion relevant transient heat loads},
	volume = {13},
	issn = {2352-1791},
	doi = {10.1016/j.nme.2017.06.008},
	abstract = {In the future fusion devices, ELMs-induced transient heat flux may lead to the surface cracking of tungsten (W) based plasma-facing materials (PFMs). In theory, the cracking is related to the material fracture toughness and the thermal stress-strain caused by transient heat flux. In this paper, a finite element model was successfully built to realize a theoretical semi infinite space. The temperature and stress-strain distribution as well as evolution of W during a single heating-cooling cycle of transient heat flux were simulated and analyzed. It showed that the generation of plastic deformation during the brittle temperature range between room temperature and DBTT (ductile to brittle transition temperature, ∼400 °C) caused the cracking of W during the cooling phase. The cracking threshold for W under transient heat flux was successfully obtained by finite element analysis, to some extent, in consistent with the similar experimental results. Both the heat flux factors (FHF = P·t0.5) and the maximum surface temperatures at cracking thresholds were almost invariant for the transient heat fluxes with different pulse widths and temporal distributions. This method not only identified the theoretical conclusion but also obtained the detail values for W with actual temperature-dependent properties.},
	urldate = {2024-04-24},
	journal = {Nuclear Materials and Energy},
	author = {Li, Changjun and Zhu, Dahuan and Li, Xiangbin and Wang, Baoguo and Chen, Junling},
	month = dec,
	year = {2017},
	keywords = {Cracking threshold, Finite element analysis, Plasma-facing materials, Tungsten},
	pages = {68--73},
}

In the future fusion devices, ELMs-induced transient heat flux may lead to the surface cracking of tungsten (W) based plasma-facing materials (PFMs). In theory, the cracking is related to the material fracture toughness and the thermal stress-strain caused by transient heat flux. In this paper, a finite element model was successfully built to realize a theoretical semi infinite space. The temperature and stress-strain distribution as well as evolution of W during a single heating-cooling cycle of transient heat flux were simulated and analyzed. It showed that the generation of plastic deformation during the brittle temperature range between room temperature and DBTT (ductile to brittle transition temperature, ∼400 °C) caused the cracking of W during the cooling phase. The cracking threshold for W under transient heat flux was successfully obtained by finite element analysis, to some extent, in consistent with the similar experimental results. Both the heat flux factors (FHF = P·t0.5) and the maximum surface temperatures at cracking thresholds were almost invariant for the transient heat fluxes with different pulse widths and temporal distributions. This method not only identified the theoretical conclusion but also obtained the detail values for W with actual temperature-dependent properties.

@phdthesis{hanquist2017a,
	address = {Ann Arbor},
	title = {Modeling of {Electron} {Transpiration} {Cooling} for {Leading} {Edges} of {Hypersonic} {Vehicles}},
	url = {http://hdl.handle.net/2027.42/138537},
	school = {University of Michigan},
	author = {Hanquist, Kyle M},
	year = {2017},
	note = {Place: Ann Arbor},
	keywords = {etc},
}

@phdthesis{scoggins2017,
	title = {Development of numerical methods and study of coupled flow, radiation, and ablation phenomena for atmospheric entry},
	url = {https://theses.hal.science/tel-01639797},
	language = {en},
	school = {Université Paris Saclay (COmUE)},
	author = {Scoggins, James},
	year = {2017},
}

@article{parussini2017,
	title = {Multi-fidelity {Gaussian} process regression for prediction of random fields},
	volume = {336},
	doi = {10.1016/j.jcp.2017.01.047},
	journal = {Journal of Computational Physics},
	author = {Parussini, L. and Venturi, D. and Perdikaris, P. and Karniadakis, G. E.},
	year = {2017},
	keywords = {Gaussian random fields, Multi-fidelity modeling, Recursive co-kriging, Uncertainty quantification},
	pages = {36--50},
}

@inproceedings{kimmel2017,
	address = {Grapevine, Texas},
	title = {{AFRL} {Ludwieg} {Tube} {Initial} {Performance}},
	doi = {10.2514/6.2017-0102},
	language = {en},
	urldate = {2023-08-08},
	booktitle = {55th {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2017-0102},
	author = {Kimmel, Roger L. and Borg, Matthew P. and Jewell, Joseph S. and Lam, KIng-Yiu and Bowersox, Rodney D. and Srinivasan, Ravi and Fuchs, Steven and Mooney, Thomas},
	month = jan,
	year = {2017},
}

@inproceedings{edwards2017,
	address = {Grapevine, Texas},
	title = {Real gas effects on receptivity to kinetic fluctuations},
	doi = {10.2514/6.2017-0070},
	language = {en},
	urldate = {2023-08-08},
	booktitle = {55th {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2017-0070},
	author = {Edwards, Luke and Tumin, Anatoli},
	month = jan,
	year = {2017},
}

@article{zhang2017,
	title = {Turbine blade tip aero-thermal management: {Some} recent advances and research outlook},
	url = {https://doi.org/10.22261/JGPPS.K7ADQC},
	doi = {10.22261/JGPPS.K7ADQC},
	journal = {Journal of the Global Power and Propulsion Society},
	author = {Zhang, Qiang and He, Li},
	year = {2017},
	keywords = {aerodynamics, gas turbine, heat transfer},
}

@article{go2017,
	title = {Thermionic {Energy} {Conversion} in the {Twenty}-first {Century}: {Advances} and {Opportunities} for {Space} and {Terrestrial} {Applications}},
	doi = {10.3389/FMECH.2017.00013},
	abstract = {Thermionic energy conversion is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous ejection of hot electrons from a surface. Although the physical mechanism has been known for over a century, it has yet to be consistently realized in a manner practical for large-scale deployment. This perspective article provides an assessment of the potential of thermionic energy conversion systems for space and terrestrial applications in the 21st century, overviewing recent advances in the field and identifying key research challenges. Recent developments as well as persisting research needs in materials, device design, fundamental understanding, and testing and validation are discussed.},
	journal = {Frontiers in Mechanical Engineering},
	author = {Go, David B. and Haase, John R. and George, Jeffrey and Mannhart, Jochen and Wanke, Robin and Nojeh, Alireza and Nemanich, Robert},
	month = nov,
	year = {2017},
	note = {Publisher: Frontiers},
	keywords = {Photo-Enhanced Thermionic Emission, Thermal energy conversion, Thermionic energy conversion, thermionic emission, thermoelectronic energy conversion},
}

Thermionic energy conversion is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous ejection of hot electrons from a surface. Although the physical mechanism has been known for over a century, it has yet to be consistently realized in a manner practical for large-scale deployment. This perspective article provides an assessment of the potential of thermionic energy conversion systems for space and terrestrial applications in the 21st century, overviewing recent advances in the field and identifying key research challenges. Recent developments as well as persisting research needs in materials, device design, fundamental understanding, and testing and validation are discussed.

@article{kazemba2017,
	title = {Survey of blunt-body supersonic dynamic stability},
	volume = {54},
	url = {https://arc.aiaa.org/doi/10.2514/1.A33552},
	doi = {10.2514/1.A33552},
	number = {1},
	journal = {Journal of Spacecraft and Rockets},
	author = {Kazemba, Cole D. and Braun, Robert D. and Clark, Ian G. and Schoenenberger, Mark},
	month = oct,
	year = {2017},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Aerodynamic Characteristics, Aerodynamic Performance, Aerospace Engineering, Flow Separation, Hypersonic Inflatable Aerodynamic Decelerator, NASA Langley Research Center, Planetary Exploration, Pressure Coefficient, Supersonic Wind Tunnels, Thermal Protection System},
	pages = {109--127},
}

@techreport{chazot2017,
	title = {Plasma {Wind} {Tunnel} {Testing} of {Electron} {Transpiration} {Cooling} {Concept}},
	author = {Chazot, Olivier and Helber, Bernd},
	year = {2017},
	note = {Issue: AD1028658},
	keywords = {etc},
}

@article{jumper2017,
	title = {Physics and {Measurement} of {Aero}-{Optical} {Efects}: {Past} and {Present}},
	volume = {49},
	number = {1},
	journal = {Annual Review of Fluid Mechanics},
	author = {Jumper, Eric J and Gordeyev, Stanislav},
	year = {2017},
	pages = {419--441},
}

@book{boyd2017,
	title = {Nonequilibrium {Gas} {Dynamics} and {Molecular} {Simulation}},
	publisher = {Cambridge University Press},
	author = {Boyd, Iain D and Schwartzentruber, Thomas E},
	year = {2017},
}

@inproceedings{buffenoir2017,
	title = {{IXV} {Thermal} {Protection} {System} {Post}-{Flight} {Preliminary} analysis},
	doi = {10.13009/EUCASS2017-330},
	author = {Buffenoir, F. and Pichon, T. and Barreteau, R.},
	year = {2017},
}

@article{estrada2017,
	title = {Improving {Underrepresented} {Minority} {Student} {Persistence} in {STEM}},
	volume = {15},
	url = {https://www.lifescied.org/doi/abs/10.1187/cbe.16-01-0038},
	doi = {10.1187/CBE.16-01-0038},
	abstract = {Members of the Joint Working Group on Improving Underrepresented Minorities (URMs) Persistence in Science, Technology, Engineering and Mathematics (STEM), utilizing Kurt Lewin’s planned approach to...},
	number = {3},
	journal = {CBE - Life Sciences Education},
	author = {Estrada, Mica and Burnett, Myra and Campbell, Andrew G. and Campbell, Patricia B. and Denetclaw, Wilfred F. and Gutiérrez, Carlos G. and Hurtado, Sylvia and John, Gilbert H. and Matsui, John and McGee, Richard and Okpodu, Camellia Moses and Robinson, T. Joan and Summers, Michael F. and Werner-Washburne, Maggie and Zavala, MariaElena},
	month = oct,
	year = {2017},
	note = {Publisher: American Society for Cell Biology},
}

Members of the Joint Working Group on Improving Underrepresented Minorities (URMs) Persistence in Science, Technology, Engineering and Mathematics (STEM), utilizing Kurt Lewin’s planned approach to...

@inproceedings{currao2017,
	title = {Hypersonic {Fluid}-{Structure} {Interaction} on a {Cantilevered} {Plate}},
	url = {https://www.researchgate.net/publication/320087702},
	doi = {10.13009/EUCASS2017-299},
	abstract = {This work is a numerical and experimental study of fluid-structure interaction at Mach 5.8. Numerical results from low-and high-fidelity models are shown and compared. Procedures and details of the generation of the numerical mesh are given. The mesh topology shape, irrespective of flow direction, shock position, and sonic line location can lead to non-physical results if not optimised. Orthogonality of the cells to the wall is fundamentally important to reach numerical convergence and reliable results. Under an inviscid point of view, piston theory is confirmed to be an appropriate tool in the evaluation of the inviscid pressure over the plate, as it showed good agreement with the empirical data. Concerning the viscous aspects, the shear stress and heat transfer histories shared the same frequency with the structural, and their spatial distribution present a degree for hysteresis. Finally, the boundary layer height changes not only according to local slope and speed of the wall, but it is a function of the actual structural mode of vibration. Nomenclature Flow Variables: q = Heat flux rate on the plate p = Pressure τ = Shear stress on the plate a = Sound speed St = Stanton number Cf = Skin friction coefficient M = Mach number Structural Variables l = Beam element's length L = Plate length T = Period of oscillation th = Plate's thickness w = Structural displacement θ = Local slope ω = Frequency (= 2πf) E = Young's modulus I = Inertia of the beam cross-section M = Mass matrix K = Stiffness matrix D ̅ = Damping matrix ζ = Damping ratio α,β = Rayleigh coefficients Other Variables x = Coordinate tangent to the wall y = Coordinate normal to the wall t = Time η = Ratio between pressure with 3D effects and 2D pressure Subscripts: w = At the wall S = Structure 1 = 1 st mode 2 = Post-shock conditions or 2 nd mode 3 = 3 rd mode ∞ = Freestream conditions Abbreviations: BL = Boundary layer LE = Leading edge PT1= Pressure transducer near the hinge line PT2= Pressure transducer near the trailing edge PT3= Pressure transducer beneath the plate TE = Trailing edge TUSQ = Wind tunnel at University of Southern Queensland},
	author = {Currao, Gaetano and Neely, Andrew and Robert Buttsworth, David and Gai, S.},
	year = {2017},
}

This work is a numerical and experimental study of fluid-structure interaction at Mach 5.8. Numerical results from low-and high-fidelity models are shown and compared. Procedures and details of the generation of the numerical mesh are given. The mesh topology shape, irrespective of flow direction, shock position, and sonic line location can lead to non-physical results if not optimised. Orthogonality of the cells to the wall is fundamentally important to reach numerical convergence and reliable results. Under an inviscid point of view, piston theory is confirmed to be an appropriate tool in the evaluation of the inviscid pressure over the plate, as it showed good agreement with the empirical data. Concerning the viscous aspects, the shear stress and heat transfer histories shared the same frequency with the structural, and their spatial distribution present a degree for hysteresis. Finally, the boundary layer height changes not only according to local slope and speed of the wall, but it is a function of the actual structural mode of vibration. Nomenclature Flow Variables: q = Heat flux rate on the plate p = Pressure τ = Shear stress on the plate a = Sound speed St = Stanton number Cf = Skin friction coefficient M = Mach number Structural Variables l = Beam element's length L = Plate length T = Period of oscillation th = Plate's thickness w = Structural displacement θ = Local slope ω = Frequency (= 2πf) E = Young's modulus I = Inertia of the beam cross-section M = Mass matrix K = Stiffness matrix D ̅ = Damping matrix ζ = Damping ratio α,β = Rayleigh coefficients Other Variables x = Coordinate tangent to the wall y = Coordinate normal to the wall t = Time η = Ratio between pressure with 3D effects and 2D pressure Subscripts: w = At the wall S = Structure 1 = 1 st mode 2 = Post-shock conditions or 2 nd mode 3 = 3 rd mode ∞ = Freestream conditions Abbreviations: BL = Boundary layer LE = Leading edge PT1= Pressure transducer near the hinge line PT2= Pressure transducer near the trailing edge PT3= Pressure transducer beneath the plate TE = Trailing edge TUSQ = Wind tunnel at University of Southern Queensland

@article{hanquist2017c,
	title = {Evaluation of {Computational} {Modeling} of {Electron} {Transpiration} {Cooling} at {High} {Enthalpies}},
	volume = {31},
	doi = {10.2514/1.T4932},
	abstract = {Amodeling approach for electron transpiration cooling of high-enthalpy flight is evaluated through comparison to a set of experiments performed in a plasma arc tunnel for air and argon. The comparisons include air and argon flow at high enthalpies (27.9 and 11.6 MJ/kg, respectively), with a Mach number of 2.5 to 3. The conversion of the reported enthalpies and Mach numbers to freestream temperatures and velocities is discussed. The numerical approach is described, including implementation of a thermionic emission boundary condition and an electric field model. Also described is the implementation of a finite-rate chemistry model for argon ionization. Materials with different electron emission properties are also investigated, including graphite and tungsten. The comparisons include two different geometries with different leading-edge radii. The numerical results produce a wide range of emitted current due to the uncertainties in freestream conditions and emissive material properties, but they still agree well with the experimental measurements.},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Hanquist, Kyle M. and Alkandry, Hicham and Boyd, Iain D.},
	year = {2017},
	keywords = {etc, own},
	pages = {283--293},
}

Amodeling approach for electron transpiration cooling of high-enthalpy flight is evaluated through comparison to a set of experiments performed in a plasma arc tunnel for air and argon. The comparisons include air and argon flow at high enthalpies (27.9 and 11.6 MJ/kg, respectively), with a Mach number of 2.5 to 3. The conversion of the reported enthalpies and Mach numbers to freestream temperatures and velocities is discussed. The numerical approach is described, including implementation of a thermionic emission boundary condition and an electric field model. Also described is the implementation of a finite-rate chemistry model for argon ionization. Materials with different electron emission properties are also investigated, including graphite and tungsten. The comparisons include two different geometries with different leading-edge radii. The numerical results produce a wide range of emitted current due to the uncertainties in freestream conditions and emissive material properties, but they still agree well with the experimental measurements.

@article{schwartzentruber2017,
	title = {Direct {Molecular} {Simulation} of {Nonequilibrium} {Dilute} {Gases}},
	volume = {32},
	doi = {10.2514/1.T5188},
	number = {4},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Schwartzentruber, Thomas E and Grover, M S and Valentini, Paolo},
	year = {2017},
}

@article{hanquist2017b,
	title = {Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles},
	volume = {121},
	doi = {10.1063/1.4974961},
	number = {5},
	journal = {Journal of Applied Physics},
	author = {Hanquist, Kyle M. and Hara, Kentaro and Boyd, Iain D.},
	year = {2017},
	keywords = {own},
	pages = {1--13},
}

@article{viladegut2017,
	title = {Diffusion effects on the determination of surface catalysis in {Inductively} {Coupled} {Plasma} facility},
	volume = {485-486},
	doi = {10.1016/J.CHEMPHYS.2017.02.002},
	abstract = {Atomic recombination is an important process to consider when computing the heat flux transferred to the wall of a re-entry vehicle. Two chemical processes are influencing the species diffusion in the boundary layer surrounding a re-usable Thermal Protection System: gas phase reactions and catalytic recombination at the surface. The coupling between them is not normally taken into account when determining the catalytic recombination coefficient (γ) in plasma facilities. This work aims to provide evidence of such coupling based on both a theoretical analysis and an experimental campaign in the VKI-Plasmatron facility. Recombination coefficient measurements at off-stagnation point configuration on a linear copper calorimeter are provided. An evolution from a high-catalytic to a low-catalytic condition due to the boundary layer growth along the probe is observed. This result is consistent with a parametric analysis carried out using the in-house non-equilibrium boundary layer solver, which shows how the experimentally determined catalysis could be influenced by the amount of gas-phase recombination inside the boundary layer.},
	journal = {Chemical Physics},
	author = {Viladegut, Alan and Düzel, Ümran and Chazot, Olivier},
	month = mar,
	year = {2017},
	note = {Publisher: North-Holland},
	keywords = {Boundary layer, Chemical reactions, Flat plate, Plasmatron, Wall catalysis},
	pages = {88--97},
}

Atomic recombination is an important process to consider when computing the heat flux transferred to the wall of a re-entry vehicle. Two chemical processes are influencing the species diffusion in the boundary layer surrounding a re-usable Thermal Protection System: gas phase reactions and catalytic recombination at the surface. The coupling between them is not normally taken into account when determining the catalytic recombination coefficient (γ) in plasma facilities. This work aims to provide evidence of such coupling based on both a theoretical analysis and an experimental campaign in the VKI-Plasmatron facility. Recombination coefficient measurements at off-stagnation point configuration on a linear copper calorimeter are provided. An evolution from a high-catalytic to a low-catalytic condition due to the boundary layer growth along the probe is observed. This result is consistent with a parametric analysis carried out using the in-house non-equilibrium boundary layer solver, which shows how the experimentally determined catalysis could be influenced by the amount of gas-phase recombination inside the boundary layer.

@inproceedings{hanquist2017,
	title = {Computational analysis of electron transpiration cooling for hypersonic vehicles},
	doi = {10.2514/6.2017-0900},
	abstract = {Simulations of a leading edge of a hypersonic vehicle using computational fluid dynamics (CFD) and a material response code are presented in order to investigate the effect in-depth surface conduction has on electron transpiration cooling (ETC). ETC is a recently proposed thermal management approach. Previous numerical studies have shown that ETC can significantly lower the stagnation point surface temperature of sharp leading edges of hypersonic vehicles. However, these studies have neglected the effect of heat also being conducted into the material as opposed to only into the flow via radiative cooling and ETC. A modeling approach is presented for ETC, which includes the boundary conditions for electron emission from the surface, accounting for the electric field and space-charge limit effects within the near-wall plasma sheath. A material response code is used to determine typical values of in-depth surface conduction for the test cases studied. Since ETC materials are still being developed, a parametric study is conducted for a range of material properties pertinent to ETC. The results of this study are used to generate in-depth surface conduction profiles, which are implemented into the CFD framework. The CFD simulations show that including in-depth surface conduction results in lower surface temperatures than predicted with radiative and ETC cooling alone. This is because in-depth surface conduction complements radiative cooling and ETC by moving heat away from the surface, in the case of surface conduction by moving the energy into the material, allowing for a lower surface temperature. The results also show that ETC remains a major mode of heat transfer away from the surface, even with in-depth surface conduction. This suggests that ETC is still a promising mode of thermal management, especially since it transfers energy to the flow instead of into the material.},
	booktitle = {{AIAA} {SciTech} {Forum} - 55th {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2017-0900},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2017},
	keywords = {etc, own, ★},
	pages = {1--12},
}

Simulations of a leading edge of a hypersonic vehicle using computational fluid dynamics (CFD) and a material response code are presented in order to investigate the effect in-depth surface conduction has on electron transpiration cooling (ETC). ETC is a recently proposed thermal management approach. Previous numerical studies have shown that ETC can significantly lower the stagnation point surface temperature of sharp leading edges of hypersonic vehicles. However, these studies have neglected the effect of heat also being conducted into the material as opposed to only into the flow via radiative cooling and ETC. A modeling approach is presented for ETC, which includes the boundary conditions for electron emission from the surface, accounting for the electric field and space-charge limit effects within the near-wall plasma sheath. A material response code is used to determine typical values of in-depth surface conduction for the test cases studied. Since ETC materials are still being developed, a parametric study is conducted for a range of material properties pertinent to ETC. The results of this study are used to generate in-depth surface conduction profiles, which are implemented into the CFD framework. The CFD simulations show that including in-depth surface conduction results in lower surface temperatures than predicted with radiative and ETC cooling alone. This is because in-depth surface conduction complements radiative cooling and ETC by moving heat away from the surface, in the case of surface conduction by moving the energy into the material, allowing for a lower surface temperature. The results also show that ETC remains a major mode of heat transfer away from the surface, even with in-depth surface conduction. This suggests that ETC is still a promising mode of thermal management, especially since it transfers energy to the flow instead of into the material.

@inproceedings{sagerman2017,
	address = {Grapevine, TX},
	title = {Comparisons of {Measured} and {Modeled} {Aero}-thermal {Distributions} for {Complex} {Hypersonic} {Configurations}},
	url = {http://arc.aiaa.org},
	doi = {10.2514/6.2017-0264},
	abstract = {The ability to quickly and accurately predict the thermal signature of a complex geometry is important in the early design stages for any aircraft. Due to the lack of hypersonic facilities with this capability, a recent effort has been made to quantify the ability of the Mach 6 tunnel at Wright-Patterson Air Force Base (WPAFB) for this task. The Mach 6 High Reynolds Number Facility at WPAFB in Dayton, Ohio, has been non-operational for the past twenty years, but a recent resurgence in the need for hypersonic test facilities has led to the reactivation of the tunnel. With its restoration, the facility is to include new capabilities to assess hypersonic aero-thermodynamic effects on bodies in Mach 6 flow. Using temperature sensitive paint (TSP) and three complex geometries commonly used in the hypersonic community, experimental tests were conducted inside the Mach 6 tunnel to capture the temperature contours and some pressure data for these geometries at various angles of attack. These results were then compared to numerical analyses conducted using the panel code CBAero, the Euler code Cart3D, the coupled Euler/Boundary layer solver UNLATCH, and Navier-Stokes solutions from FUN3D. Due to the experiments in the tunnel never reaching steady state since paint adherence was affected after about 10 seconds in the high-speed flow, the comparison to steady numerical analysis proved difficult. As a result, the capabilities of the Mach 6 tunnel, in terms of having a quantifiable measure between the experimental and numerical temperature distributions, could not be assessed and instead general qualitative comparisons were made. Nomenclature a Speed of sound α or AOA Angle of attack C D Drag coefficient C L Lift coefficient C M Pitching moment coefficient C p Pressure coefficient M Mach number T Temperature [Kelvin] ρ Density},
	author = {Sagerman, Denton G and Dasque, Nastassja and Rumpfkeil, Markus P and Hellman, Barry},
	year = {2017},
}

The ability to quickly and accurately predict the thermal signature of a complex geometry is important in the early design stages for any aircraft. Due to the lack of hypersonic facilities with this capability, a recent effort has been made to quantify the ability of the Mach 6 tunnel at Wright-Patterson Air Force Base (WPAFB) for this task. The Mach 6 High Reynolds Number Facility at WPAFB in Dayton, Ohio, has been non-operational for the past twenty years, but a recent resurgence in the need for hypersonic test facilities has led to the reactivation of the tunnel. With its restoration, the facility is to include new capabilities to assess hypersonic aero-thermodynamic effects on bodies in Mach 6 flow. Using temperature sensitive paint (TSP) and three complex geometries commonly used in the hypersonic community, experimental tests were conducted inside the Mach 6 tunnel to capture the temperature contours and some pressure data for these geometries at various angles of attack. These results were then compared to numerical analyses conducted using the panel code CBAero, the Euler code Cart3D, the coupled Euler/Boundary layer solver UNLATCH, and Navier-Stokes solutions from FUN3D. Due to the experiments in the tunnel never reaching steady state since paint adherence was affected after about 10 seconds in the high-speed flow, the comparison to steady numerical analysis proved difficult. As a result, the capabilities of the Mach 6 tunnel, in terms of having a quantifiable measure between the experimental and numerical temperature distributions, could not be assessed and instead general qualitative comparisons were made. Nomenclature a Speed of sound α or AOA Angle of attack C D Drag coefficient C L Lift coefficient C M Pitching moment coefficient C p Pressure coefficient M Mach number T Temperature [Kelvin] ρ Density

@inproceedings{brock2017,
	title = {{CFD} simulations of the supersonic inflatable aerodynamic decelerator ({SIAD}) ballistic range tests},
	isbn = {978-1-62410-447-3},
	url = {https://arc.aiaa.org/doi/10.2514/6.2017-1437},
	doi = {10.2514/6.2017-1437},
	abstract = {A series of ballistic range tests were performed on a scaled model of the Supersonic Flight Demonstration Test (SFDT) intended to test the Supersonic Inflatable Aerodynamic Decelerator (SIAD) geometry. The purpose of these experiments were to provide aerodynamic coefficients of the vehicle to aid in mission and vehicle design. The experimental data spans the moderate Mach number range, 3:8-2:0, with a total angle of attack (αT) range, 10°-20°. These conditions are intended to span the Mach-α space for the majority of the SFDT experiment. In an effort to validate the predictive capabilities of Computational Fluid Dynamics (CFD) for free-flight aerodynamic behavior, numerical simulations of the ballistic range experiment are performed using the unstructured finite volume Navier-Stokes solver, US3. D. Comparisons to raw vehicle attitude, and post-processed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data gives further insights into dynamic/flow coupling leading to a potential mechanism for dynamic instability.},
	publisher = {AIAA Paper 2017-1437},
	author = {Brock, Joseph M. and Stern, Eric C. and Wilder, Michael C.},
	year = {2017},
}

A series of ballistic range tests were performed on a scaled model of the Supersonic Flight Demonstration Test (SFDT) intended to test the Supersonic Inflatable Aerodynamic Decelerator (SIAD) geometry. The purpose of these experiments were to provide aerodynamic coefficients of the vehicle to aid in mission and vehicle design. The experimental data spans the moderate Mach number range, 3:8-2:0, with a total angle of attack (αT) range, 10°-20°. These conditions are intended to span the Mach-α space for the majority of the SFDT experiment. In an effort to validate the predictive capabilities of Computational Fluid Dynamics (CFD) for free-flight aerodynamic behavior, numerical simulations of the ballistic range experiment are performed using the unstructured finite volume Navier-Stokes solver, US3. D. Comparisons to raw vehicle attitude, and post-processed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data gives further insights into dynamic/flow coupling leading to a potential mechanism for dynamic instability.

@inproceedings{neitzel2017b,
	title = {Aerodynamic optimization of a golf driver using computational fluid dynamics},
	doi = {10.2514/6.2017-0724},
	abstract = {Driving distance and accuracy are the two key characteristics to an ideal golf drive. Besides having correct swing mechanics, there are numerous approaches that have been advanced to improve driver distance and accuracy, including driver shape, size, and material throughout the history of golf. Currently, with strict equipment conformity regulations from the United States Golf Association (USGA), the shape of the golf driver is greatly bounded, resulting in designs with marked improvements in design performance becoming less common. The required blunt body shape of the golf driver leads itself to be highly affected by aerodynamic forces, specifically pressure and viscous drag. Although the general shape of the golf driver head is greatly defined, small changes in shape can affect the aerodynamics significantly. This paper focusing on using Navier-Stokes computational fluid dynamic (CFD) simulations to reduce the aerodynamic drag while also increasing the yaw stability of the golf driver. Results include a characterization of the flow field experienced during a golf swing as well as the drag analysis of a generic driver. The adjoint method is used to identify surfaces on the driver that are most sensitive to drag. Finally, an optimization approach is discussed to create a low-drag, stable driver with design constraints such as USGA conformity and other parameters important to driver design such as a low center-of-mass and high moment-of-inertia.},
	booktitle = {{AIAA} {SciTech} {Forum} - 55th {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2017-0724},
	author = {Neitzel, Kevin J. and Hanquist, Kyle M.},
	year = {2017},
	keywords = {own, ★},
	pages = {1--8},
}

Driving distance and accuracy are the two key characteristics to an ideal golf drive. Besides having correct swing mechanics, there are numerous approaches that have been advanced to improve driver distance and accuracy, including driver shape, size, and material throughout the history of golf. Currently, with strict equipment conformity regulations from the United States Golf Association (USGA), the shape of the golf driver is greatly bounded, resulting in designs with marked improvements in design performance becoming less common. The required blunt body shape of the golf driver leads itself to be highly affected by aerodynamic forces, specifically pressure and viscous drag. Although the general shape of the golf driver head is greatly defined, small changes in shape can affect the aerodynamics significantly. This paper focusing on using Navier-Stokes computational fluid dynamic (CFD) simulations to reduce the aerodynamic drag while also increasing the yaw stability of the golf driver. Results include a characterization of the flow field experienced during a golf swing as well as the drag analysis of a generic driver. The adjoint method is used to identify surfaces on the driver that are most sensitive to drag. Finally, an optimization approach is discussed to create a low-drag, stable driver with design constraints such as USGA conformity and other parameters important to driver design such as a low center-of-mass and high moment-of-inertia.

@article{neitzel2017c,
	title = {Aerothermochemical {Nonequilibrium} {Modeling} for {Oxygen} {Flows}},
	volume = {31},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Neitzel, K J and Andrienko, D A and Boyd, I D},
	year = {2017},
	pages = {634--645},
}

@article{sahai2017,
	title = {Adaptive coarse graining method for energy transfer and dissociation kinetics of polyatomic species},
	volume = {147},
	doi = {10.1063/1.4996654},
	abstract = {A novel reduced-order method is presented for modeling reacting flows characterized by strong non-equilibrium of the internal energy level distribution of chemical species in the gas. The approach ...},
	number = {5},
	journal = {The Journal of Chemical Physics},
	author = {Sahai, A. and Lopez, B. and Johnston, C. O. and Panesi, M.},
	month = aug,
	year = {2017},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	keywords = {chemically reactive flow, dissociation, master equation, maximum entropy methods, nitrogen, reduced order systems},
	pages = {054107--054107},
}

A novel reduced-order method is presented for modeling reacting flows characterized by strong non-equilibrium of the internal energy level distribution of chemical species in the gas. The approach ...

@article{choi2017,
	title = {A {Study} on {Re}-entry {Predictions} of {Uncontrolled} {Space} {Objects} for {Space} {Situational} {Awareness}},
	volume = {34},
	doi = {10.5140/JASS.2017.34.4.289},
	abstract = {The key risk analysis technologies for the re-entry of space objects into Earth's atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on re-entry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d'Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth's atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.},
	number = {4},
	journal = {J. Astron. Space Sci},
	author = {Choi, Eun-Jung and Cho, Sungki and Lee, Deok-Jin and Kim, Siwoo and Hyun Jo, Jung},
	year = {2017},
	keywords = {re-entry prediction, space situational awareness, uncontrolled space objects},
	pages = {289--302},
}

The key risk analysis technologies for the re-entry of space objects into Earth's atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on re-entry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d'Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth's atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.

@article{haack2017,
	title = {A {Conservative}, {Entropic} {Multispecies} {BGK} {Model}},
	volume = {168},
	doi = {10.1007/S10955-017-1824-9/FIGURES/5},
	abstract = {We derive a conservative multispecies BGK model that follows the spirit of the original, single species BGK model by making the specific choice to conserve species masses, total momentum, and total kinetic energy and to satisfy Boltzmann’s H-Theorem. The derivation emphasizes the connection to the Boltzmann operator which allows for direct inclusion of information from higher-fidelity collision physics models. We also develop a complete hydrodynamic closure via the Chapman-Enskog expansion, including a general procedure to generate symmetric diffusion coefficients based on this model. We numerically investigate velocity and temperature relaxation in dense plasmas and compare the model with previous multispecies BGK models and discuss the trade-offs that are made in defining and using them. In particular, we demonstrate that the BGK model in the NRL plasma formulary does not conserve momentum or energy in general.},
	number = {4},
	journal = {Journal of Statistical Physics},
	author = {Haack, Jeffrey R. and Hauck, Cory D. and Murillo, Michael S.},
	month = aug,
	year = {2017},
	note = {Publisher: Springer New York LLC},
	keywords = {BGK, Boltzmann equation, H theorem, Kinetic theory, Multispecies flow, Plasma physics, Transport coefficients},
	pages = {826--856},
}

We derive a conservative multispecies BGK model that follows the spirit of the original, single species BGK model by making the specific choice to conserve species masses, total momentum, and total kinetic energy and to satisfy Boltzmann’s H-Theorem. The derivation emphasizes the connection to the Boltzmann operator which allows for direct inclusion of information from higher-fidelity collision physics models. We also develop a complete hydrodynamic closure via the Chapman-Enskog expansion, including a general procedure to generate symmetric diffusion coefficients based on this model. We numerically investigate velocity and temperature relaxation in dense plasmas and compare the model with previous multispecies BGK models and discuss the trade-offs that are made in defining and using them. In particular, we demonstrate that the BGK model in the NRL plasma formulary does not conserve momentum or energy in general.

@article{economon2016,
	title = {{SU2}: {An} open-source suite for multiphysics simulation and design},
	volume = {54},
	doi = {10.2514/1.J053813},
	abstract = {This paper presents the main objectives and a description of the SU2 suite, including the novel software architecture and open-source software engineering strategy. SU2 is a computational analysis and design package that has been developed to solve multiphysics analysis and optimization tasks using unstructured mesh topologies. Its unique architecture iswell suited for extensibility to treat partial-differential-equation-based problems not initially envisioned. The common framework adopted enables the rapid implementation of newphysics packages that can be tightly coupled to form a powerful ensemble of analysis tools to address complex problems facing many engineering communities. The framework is demonstrated on a number, solving both the flow and adjoint systems of equations to provide a highfidelity predictive capability and sensitivity information that can be used for optimal shape design using a gradientbased framework, goal-oriented adaptive mesh refinement, or uncertainty quantification.},
	number = {3},
	journal = {AIAA Journal},
	author = {Economon, Thomas D. and Palacios, Francisco and Copeland, Sean R. and Lukaczyk, Trent W. and Alonso, Juan J.},
	year = {2016},
	pages = {828--846},
}

This paper presents the main objectives and a description of the SU2 suite, including the novel software architecture and open-source software engineering strategy. SU2 is a computational analysis and design package that has been developed to solve multiphysics analysis and optimization tasks using unstructured mesh topologies. Its unique architecture iswell suited for extensibility to treat partial-differential-equation-based problems not initially envisioned. The common framework adopted enables the rapid implementation of newphysics packages that can be tightly coupled to form a powerful ensemble of analysis tools to address complex problems facing many engineering communities. The framework is demonstrated on a number, solving both the flow and adjoint systems of equations to provide a highfidelity predictive capability and sensitivity information that can be used for optimal shape design using a gradientbased framework, goal-oriented adaptive mesh refinement, or uncertainty quantification.

@misc{dufrene2016,
	title = {Space {Launch} {System} {Base} {Heating} {Test}: {Experimental} {Operations} and {Results}},
	url = {https://web.archive.org/web/20190429090136id_/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160001817.pdf},
	author = {Dufrene, Aaron and MacLean, Matthew and Holden, Michael and Mehta, Manish and Seaford, Mark},
	month = jan,
	year = {2016},
}

@article{wilkinson2016,
	title = {The {FAIR} {Guiding} {Principles} for scientific data management and stewardship},
	volume = {3},
	copyright = {2016 The Author(s)},
	issn = {2052-4463},
	doi = {10.1038/sdata.2016.18},
	abstract = {There is an urgent need to improve the infrastructure supporting the reuse of scholarly data. A diverse set of stakeholders—representing academia, industry, funding agencies, and scholarly publishers—have come together to design and jointly endorse a concise and measureable set of principles that we refer to as the FAIR Data Principles. The intent is that these may act as a guideline for those wishing to enhance the reusability of their data holdings. Distinct from peer initiatives that focus on the human scholar, the FAIR Principles put specific emphasis on enhancing the ability of machines to automatically find and use the data, in addition to supporting its reuse by individuals. This Comment is the first formal publication of the FAIR Principles, and includes the rationale behind them, and some exemplar implementations in the community.},
	language = {en},
	number = {1},
	urldate = {2024-04-25},
	journal = {Scientific Data},
	author = {Wilkinson, Mark D. and Dumontier, Michel and Aalbersberg, IJsbrand Jan and Appleton, Gabrielle and Axton, Myles and Baak, Arie and Blomberg, Niklas and Boiten, Jan-Willem and da Silva Santos, Luiz Bonino and Bourne, Philip E. and Bouwman, Jildau and Brookes, Anthony J. and Clark, Tim and Crosas, Mercè and Dillo, Ingrid and Dumon, Olivier and Edmunds, Scott and Evelo, Chris T. and Finkers, Richard and Gonzalez-Beltran, Alejandra and Gray, Alasdair J. G. and Groth, Paul and Goble, Carole and Grethe, Jeffrey S. and Heringa, Jaap and ’t Hoen, Peter A. C. and Hooft, Rob and Kuhn, Tobias and Kok, Ruben and Kok, Joost and Lusher, Scott J. and Martone, Maryann E. and Mons, Albert and Packer, Abel L. and Persson, Bengt and Rocca-Serra, Philippe and Roos, Marco and van Schaik, Rene and Sansone, Susanna-Assunta and Schultes, Erik and Sengstag, Thierry and Slater, Ted and Strawn, George and Swertz, Morris A. and Thompson, Mark and van der Lei, Johan and van Mulligen, Erik and Velterop, Jan and Waagmeester, Andra and Wittenburg, Peter and Wolstencroft, Katherine and Zhao, Jun and Mons, Barend},
	month = mar,
	year = {2016},
	keywords = {Publication characteristics, Research data},
	pages = {160018},
}

There is an urgent need to improve the infrastructure supporting the reuse of scholarly data. A diverse set of stakeholders—representing academia, industry, funding agencies, and scholarly publishers—have come together to design and jointly endorse a concise and measureable set of principles that we refer to as the FAIR Data Principles. The intent is that these may act as a guideline for those wishing to enhance the reusability of their data holdings. Distinct from peer initiatives that focus on the human scholar, the FAIR Principles put specific emphasis on enhancing the ability of machines to automatically find and use the data, in addition to supporting its reuse by individuals. This Comment is the first formal publication of the FAIR Principles, and includes the rationale behind them, and some exemplar implementations in the community.

@inproceedings{hanquist2016e,
	title = {Modeling of electron transpiration cooling for hypersonic vehicles},
	doi = {10.2514/6.2016-4433},
	abstract = {Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes devloping the boundary conditions for electron emission from the surface, accounting for the electric field and space-charge limit effects within the near-wall plasma sheath. Two different analytical models for space-charge limited emission are discussed. The first model assumes that the electrons are emitted cold from the surface while in the second approach the emitted electrons have a finite temperature. The theory shows that emitted electrons with a finite temperature, referred to as warm emission in the present paper, can reach higher levels of emission. This is important because the benefit of ETC, mainly reduction in the surface temperature, is directly correlated to the level of electron emission from the surface. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature. Both models are implemented into a CFD code, LeMANS, and run for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show finite temperature theory results in a larger reduction in wall temperature because more electron emission is allowed for than the cold emission theory. However, even with the electrons being emitted with a finite temperature, the emission still reaches space-charge limits for the test case considered, which can limit the benefits of ETC.},
	booktitle = {46th {AIAA} {Thermophysics} {Conference}},
	publisher = {AIAA Paper 2016-4433},
	author = {Hanquist, Kyle M. and Hara, Kentaro and Boyd, Iain D.},
	year = {2016},
	keywords = {etc, own, ★},
	pages = {1--12},
}

Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes devloping the boundary conditions for electron emission from the surface, accounting for the electric field and space-charge limit effects within the near-wall plasma sheath. Two different analytical models for space-charge limited emission are discussed. The first model assumes that the electrons are emitted cold from the surface while in the second approach the emitted electrons have a finite temperature. The theory shows that emitted electrons with a finite temperature, referred to as warm emission in the present paper, can reach higher levels of emission. This is important because the benefit of ETC, mainly reduction in the surface temperature, is directly correlated to the level of electron emission from the surface. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature. Both models are implemented into a CFD code, LeMANS, and run for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show finite temperature theory results in a larger reduction in wall temperature because more electron emission is allowed for than the cold emission theory. However, even with the electrons being emitted with a finite temperature, the emission still reaches space-charge limits for the test case considered, which can limit the benefits of ETC.

@article{klothakis2016,
	title = {Validation simulations of the {DSMC} code {SPARTA}},
	volume = {1786},
	issn = {9780735414488},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.4967566},
	doi = {10.1063/1.4967566},
	abstract = {The Direct Simulation Monte Carlo (DSMC) method has been used for over 50 years to simulate rarified gas flows for a wide range of applications where continuum assumptions fail. Extensive efforts t...},
	number = {1},
	journal = {AIP Conference Proceedings},
	author = {Klothakis, A. G. and Nikolos, I. K. and Koehler, T. P. and Gallis, M. A. and Plimpton, S. J.},
	month = nov,
	year = {2016},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
}

The Direct Simulation Monte Carlo (DSMC) method has been used for over 50 years to simulate rarified gas flows for a wide range of applications where continuum assumptions fail. Extensive efforts t...

@article{neitzel2016,
	title = {Thermochemical {Modeling} of {Nonequilibrium} {Oxygen} {Flows}},
	author = {Neitzel, K J},
	year = {2016},
	note = {Place: Ann Arbor},
}

@article{economon2016a,
	title = {{SU2}: {An} open-source suite for multiphysics simulation and design},
	volume = {54},
	doi = {10.2514/1.J053813},
	abstract = {This paper presents the main objectives and a description of the SU2 suite, including the novel software architecture and open-source software engineering strategy. SU2 is a computational analysis and design package that has been developed to solve multiphysics analysis and optimization tasks using unstructured mesh topologies. Its unique architecture iswell suited for extensibility to treat partial-differential-equation-based problems not initially envisioned. The common framework adopted enables the rapid implementation of newphysics packages that can be tightly coupled to form a powerful ensemble of analysis tools to address complex problems facing many engineering communities. The framework is demonstrated on a number, solving both the flow and adjoint systems of equations to provide a highfidelity predictive capability and sensitivity information that can be used for optimal shape design using a gradientbased framework, goal-oriented adaptive mesh refinement, or uncertainty quantification.},
	number = {3},
	journal = {AIAA Journal},
	author = {Economon, Thomas D. and Palacios, Francisco and Copeland, Sean R. and Lukaczyk, Trent W. and Alonso, Juan J.},
	year = {2016},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	pages = {828--846},
}

This paper presents the main objectives and a description of the SU2 suite, including the novel software architecture and open-source software engineering strategy. SU2 is a computational analysis and design package that has been developed to solve multiphysics analysis and optimization tasks using unstructured mesh topologies. Its unique architecture iswell suited for extensibility to treat partial-differential-equation-based problems not initially envisioned. The common framework adopted enables the rapid implementation of newphysics packages that can be tightly coupled to form a powerful ensemble of analysis tools to address complex problems facing many engineering communities. The framework is demonstrated on a number, solving both the flow and adjoint systems of equations to provide a highfidelity predictive capability and sensitivity information that can be used for optimal shape design using a gradientbased framework, goal-oriented adaptive mesh refinement, or uncertainty quantification.

@inproceedings{munafo2016,
	title = {State-to-state and reduced-order models for dissociation and energy transfer in aerothermal environments},
	volume = {0},
	isbn = {978-1-62410-393-3},
	doi = {10.2514/6.2016-0505},
	abstract = {This work focuses on the development of State-to-State and reduced-order models for dissociation and energy transfer in aerothermodynamics. The reduction is realized by grouping the population of elementary states into energy bins based on Maxwell-Boltzmann distributions. Different grouping strategies are investigated. Kinetic and thermodynamic data are taken from the rovibrational ab-initio database for the N(4Su)-N2(1Σ+g) system developed at NASA Ames research center. Applications consider the steady expanding flow within the nozzle of the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. Numerical solutions are obtained by using a decoupled implicit method. Results show that the population of high-lying vibrational and rotational states depart from the local equilibrium (i.e. Boltzmann distribution). The comparison between the State-to-State and reduced-order model solutions shows that the macroscopic re-combination can be predicted by using only three energy groups.},
	publisher = {AIAA Paper 2016-0505},
	author = {Munafò, Alessandro and Venturi, Simone and Macdonald, Obyn and Panesi, Marco},
	year = {2016},
}

This work focuses on the development of State-to-State and reduced-order models for dissociation and energy transfer in aerothermodynamics. The reduction is realized by grouping the population of elementary states into energy bins based on Maxwell-Boltzmann distributions. Different grouping strategies are investigated. Kinetic and thermodynamic data are taken from the rovibrational ab-initio database for the N(4Su)-N2(1Σ+g) system developed at NASA Ames research center. Applications consider the steady expanding flow within the nozzle of the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. Numerical solutions are obtained by using a decoupled implicit method. Results show that the population of high-lying vibrational and rotational states depart from the local equilibrium (i.e. Boltzmann distribution). The comparison between the State-to-State and reduced-order model solutions shows that the macroscopic re-combination can be predicted by using only three energy groups.

@article{andrienko2016,
	title = {Rovibrational energy transfer and dissociation in \{{O}\}{\textbackslash}textsubscript\{2\}-\{{O}\} collisions},
	volume = {144},
	number = {10},
	journal = {The Journal of Chemical Physics},
	author = {Andrienko, D A and Boyd, I D},
	year = {2016},
	pages = {1--19},
}

@inproceedings{vogiatzis2016,
	address = {Washington, D.C.},
	title = {Role of {High} {Fidelity} {Nonequilibrium} {Modeling} in {Laminar} and {Turbulent} {Flows} for {High} {Speed} {ISR} {Missions}},
	publisher = {AIAA 2016-4317},
	author = {Vogiatzis, Konstantinos and Josyula, Eswar and Vedula, Prakash},
	month = jun,
	year = {2016},
}

@article{kammara2016,
	title = {Molecular {Dynamics} {Study} of {Gas}–{Surface} {Interactions} in a {Force}-{Driven} {Flow} of {Argon} through a {Rectangular} {Nanochannel}},
	volume = {20},
	url = {https://www.tandfonline.com/doi/abs/10.1080/15567265.2016.1215364},
	doi = {10.1080/15567265.2016.1215364},
	abstract = {In recent times, flows through micro- and nanochannels have gained prominence due to their applicability to the fast growing fields of micro- and nanotechnology among others. Understanding gas–surf...},
	number = {2},
	journal = {Nanoscale and Microscale Thermophysical Engineering},
	author = {Kammara, Kishore K. and Malaikannan, G. and Kumar, Rakesh},
	month = apr,
	year = {2016},
	note = {Publisher: Taylor \& Francis},
	keywords = {Gas-surface interactions, Nano-Poiseuille flow, molecular dynamics method},
	pages = {121--136},
}

In recent times, flows through micro- and nanochannels have gained prominence due to their applicability to the fast growing fields of micro- and nanotechnology among others. Understanding gas–surf...

@inproceedings{santiagopadron2016,
	title = {Multi-fidelity methods in aerodynamic robust optimization},
	isbn = {978-1-62410-397-1},
	url = {https://arc.aiaa.org/doi/abs/10.2514/6.2016-0680},
	doi = {10.2514/6.2016-0680},
	abstract = {In order to design robust and reliable aerospace systems it is necessary to properly quantify the effect of uncertainties on the systems’ behavior. Performing a robust optimization with the highest fidelity method is desired albeit not feasible because of the prohibited computational cost associated with the many simulations needed in the optimization iterations to compute statistics of the system's performance. Here we describe a multi-fidelity method to enable high-fidelity robust optimization. Our multi-fidelity method uses a polynomial chaos expansion constructed from the combination of a low-fidelity model and a model correction to approximate the high-fidelity statistics and the gradients of the statistics used in each optimization iteration. The model correction accounts for the difference between the high-fidelity (Computational Fluid Dynamics RANS) model and the low-fidelity (CFD Euler) model. A key feature of the multi-fidelity method is its incorporation of analytic gradients (adjoints) from the CFD to obtain the gradients of the statistics. The application of the multi-fidelity method to the robust optimization of an RAE2822 airfoil subject to uncertain flow conditions shows that 60\% to 90\% computational savings can be achieved when compared to the high-fidelity optimization.},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	author = {Santiago Padrón, A. and Alonso, Juan J. and Eldred, Michael S.},
	year = {2016},
}

In order to design robust and reliable aerospace systems it is necessary to properly quantify the effect of uncertainties on the systems’ behavior. Performing a robust optimization with the highest fidelity method is desired albeit not feasible because of the prohibited computational cost associated with the many simulations needed in the optimization iterations to compute statistics of the system's performance. Here we describe a multi-fidelity method to enable high-fidelity robust optimization. Our multi-fidelity method uses a polynomial chaos expansion constructed from the combination of a low-fidelity model and a model correction to approximate the high-fidelity statistics and the gradients of the statistics used in each optimization iteration. The model correction accounts for the difference between the high-fidelity (Computational Fluid Dynamics RANS) model and the low-fidelity (CFD Euler) model. A key feature of the multi-fidelity method is its incorporation of analytic gradients (adjoints) from the CFD to obtain the gradients of the statistics. The application of the multi-fidelity method to the robust optimization of an RAE2822 airfoil subject to uncertain flow conditions shows that 60% to 90% computational savings can be achieved when compared to the high-fidelity optimization.

@article{tumuklu2016,
	title = {Modeling of near-continuum laminar boundary layer shocks using {DSMC}},
	volume = {1786},
	issn = {9780735414488},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.4967554},
	doi = {10.1063/1.4967554},
	abstract = {The hypersonic flow of nitrogen gas over a double wedge was simulated by the DSMC method using two-dimensional and three-dimensional geometries. The numerical results were compared with experiments...},
	number = {1},
	journal = {AIP Conference Proceedings},
	author = {Tumuklu, Ozgur and Levin, Deborah A. and Gimelshein, Sergey F. and Austin, Joanna M.},
	month = nov,
	year = {2016},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	keywords = {DSMC, Hypersonic separated flows, Shock-wave boundary layer interactions},
	pages = {050004--050004},
}

The hypersonic flow of nitrogen gas over a double wedge was simulated by the DSMC method using two-dimensional and three-dimensional geometries. The numerical results were compared with experiments...

@inproceedings{alonso2016a,
	title = {Mesh {Adaptation} for {SU2} with the {INRIA} {AMG} {Library}},
	booktitle = {1st {Annual} {SU2} {Developers} {Meeting}},
	author = {Alonso, J. and Economon, T. and Menier, V.},
	year = {2016},
}

@inproceedings{alonso2016,
	title = {Mesh {Adaptation} for {SU2} with the {INRIA} {AMG} {Library}},
	author = {Alonso, J. and Economon, T. and Menier, V.},
	year = {2016},
}

@article{owen2016,
	title = {Measurements of {Oxygen} {Dissociation} {Using} {Laser} {Absorption}},
	volume = {30},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Owen, K G and Davidson, D F and Hanson, R K},
	year = {2016},
}

@inproceedings{hanquist2016d,
	title = {Limits for thermionic emission from leading edges of hypersonic vehicles},
	doi = {10.2514/6.2016-0507},
	abstract = {Simulations of electron transpiration cooling (ETC) on the leading edge of a hypersonic vehicle using computational fluid dynamics (CFD) are presented. The thermionic emission boundary condition and electric field model including forced diffusion are discussed. Different analytical models are used to describe the plasma sheath physics in order to avoid resolving the sheath in the computational domain. The first analytical model does not account for emission in the sheath model, so the emission is only limited by the surface temperature. The second approach models the emissive surface as electronically floated, which greatly limits the emission. The last analytical approach biases the emissive surface, which makes it possible to overcome space-charge limits. Each approach is compared and a parametric study is performed to understand the effects that the material work function, freestream velocity, and leading edge geometry has on the ETC effect. The numerical results reveal that modeling the sheath as a floated surface results in the emission, and thus ETC benefits, being greatly limited. However, if the surface is negatively biased, the results show that the emission can overcome space-charge limits and achieve the ideal ETC benefits predicted by temperature limited emission. The study also shows that, along with negatively biasing the surface, emission is enhanced by increasing the number of electrons in the external flowfield by increasing the freestream velocity.},
	booktitle = {54th {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2016-0507},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2016},
	keywords = {etc, own, ★},
	pages = {1--15},
}

Simulations of electron transpiration cooling (ETC) on the leading edge of a hypersonic vehicle using computational fluid dynamics (CFD) are presented. The thermionic emission boundary condition and electric field model including forced diffusion are discussed. Different analytical models are used to describe the plasma sheath physics in order to avoid resolving the sheath in the computational domain. The first analytical model does not account for emission in the sheath model, so the emission is only limited by the surface temperature. The second approach models the emissive surface as electronically floated, which greatly limits the emission. The last analytical approach biases the emissive surface, which makes it possible to overcome space-charge limits. Each approach is compared and a parametric study is performed to understand the effects that the material work function, freestream velocity, and leading edge geometry has on the ETC effect. The numerical results reveal that modeling the sheath as a floated surface results in the emission, and thus ETC benefits, being greatly limited. However, if the surface is negatively biased, the results show that the emission can overcome space-charge limits and achieve the ideal ETC benefits predicted by temperature limited emission. The study also shows that, along with negatively biasing the surface, emission is enhanced by increasing the number of electrons in the external flowfield by increasing the freestream velocity.

@article{sellier2016,
	title = {Inverse problems in free surface flows: a review},
	volume = {227},
	doi = {10.1007/s00707-015-1477-1},
	abstract = {Free surface flows occur frequently in our daily lives and many natural or industrial settings. Our understanding of such flows has grown tremendously with progress in mathematical modelling and numerical simulations. As a consequence, the response of a free surface to an external perturbation can often be computed and quantified. The free surface response is characteristic of the imposed perturbation and can be thought of as the signature of this perturbation. In this review paper, we survey the literature which deals with the inverse problem of identifying unknown flow conditions or fluid properties from an observed response of the free surface.},
	journal = {Acta Mech},
	author = {Sellier, Mathieu},
	year = {2016},
	pages = {913--935},
}

Free surface flows occur frequently in our daily lives and many natural or industrial settings. Our understanding of such flows has grown tremendously with progress in mathematical modelling and numerical simulations. As a consequence, the response of a free surface to an external perturbation can often be computed and quantified. The free surface response is characteristic of the imposed perturbation and can be thought of as the signature of this perturbation. In this review paper, we survey the literature which deals with the inverse problem of identifying unknown flow conditions or fluid properties from an observed response of the free surface.

@inproceedings{ward2016,
	title = {Inverse {Method} for {Determination} of the {In} {Situ} {Hydrodynamic} {Load} {Distribution} in {Multi}-{Phase} {Flow}},
	url = {https://www.researchgate.net/publication/308627046},
	author = {Ward, Jacob and Harwood, Casey M and Young, Yin Lu},
	year = {2016},
}

@article{zhang2016,
	title = {Hard-sphere/pseudo-particle modelling ({HS}-{PPM}) for efficient and scalable molecular simulation of dilute gaseous flow and transport},
	volume = {42},
	url = {https://www.tandfonline.com/doi/abs/10.1080/08927022.2016.1154551},
	doi = {10.1080/08927022.2016.1154551},
	abstract = {Continuum methods are not accurate enough for flows at high Knudsen numbers, whereas rigorous molecular dynamics (MD) methods are too costly for simulations at practical dimensions. Hard-sphere (HS...},
	number = {14},
	journal = {Molecular Simulation},
	author = {Zhang, Chenglong and Shen, Guofei and Li, Chengxiang and Ge, Wei and Li, Jinghai},
	month = sep,
	year = {2016},
	note = {Publisher: Taylor \& Francis},
	keywords = {Dilute gas, hard-sphere, high Knudsen number, micro chemical engineering, micro-flow, molecular dynamics simulation, pseudo-particle modelling},
	pages = {1171--1182},
}

Continuum methods are not accurate enough for flows at high Knudsen numbers, whereas rigorous molecular dynamics (MD) methods are too costly for simulations at practical dimensions. Hard-sphere (HS...

@inproceedings{albring2016,
	title = {Efficient {Aerodynamic} {Design} using the {Discrete} {Adjoint} {Method} in {SU2}},
	doi = {10.2514/6.2016-3518},
	publisher = {AIAA 2016-3518},
	author = {Albring, Tim and Sagebaum, Max and Gauger, Nicolas R},
	year = {2016},
}

@inproceedings{brouwer2016,
	address = {San Diego, CA},
	title = {Efficient {Treatment} of {Structural} {Deformation} for {Aerothermoelastic} {Loads} {Prediction} in {High}-{Speed} {Flows}},
	doi = {10.2514/6.2016-1089},
	abstract = {Accurate and efficient prediction of aerodynamic loads for lightweight aerospace systems is critical to the development of modern reusable high-speed platforms. This is particularly challenging to achieve for structures that exhibit higher order local deformations which, when coupled with invsicid-viscous interactions and non-isentropic flow, can lead to significant local variations in the aerodynamic loads. This study is focused on comparing two strategies for computing aerodynamic pressure loads in order to identify an accurate and efficient approach that requires minimal a priori assumptions regarding the structural response. The first strategy relies on parameterization of the structure in terms of a set of characteristic shapes. The characteristic shapes are identified by exciting the structure of interest using a representative load and then extracting the dominant features of the response. The set of characteristic shapes are then used to generate fluid loads from a Reynold's Averaged Navier-Stokes solution. The second strategy relies on approximate fluid models to compute the aerodynamic pressure. The approximate models considered as part of this study include classical piston theory, a local piston theory method where relevant freestream parameters are replaced by spatially local quantities , and an inviscid-viscous interaction model that attempts to account for the presence of the viscous boundary layer over a deformed surface. The various approaches are compared against Reynold's Averaged Navier-Stokes solutions in the context of a two-dimensional compliant panel subject to shock impingement. The results of this study indicate the following: 1) Accurate and efficient parameteriza-tion of the structure using characteristic shapes is possible, assuming that representative loads are used to excite the structure, 2) The pressure is relatively insensitive to reconstruction errors of structural displacements fit to a truncated set of modes, and 3) Approximate fluid models are capable of reasonably accurate and efficient prediction of pressure loads for a compliant panel subject to shock impingement. Nomenclature A Amplitude a Speed of sound C Covariance matrix C f Coefficient of skin friction c Constant D Flexural stiffness E Young's Modulus f Frequency H Boundary layer shape factor h Panel thickness L Panel length M Mach number m Total number of nodes in each snapshot N Total number of snapshots P Fluid pressure P N oise White noise pressure load},
	author = {Brouwer, Kirk R and Gogulapati, Abhijit and Mcnamara, Jack J},
	year = {2016},
}

Accurate and efficient prediction of aerodynamic loads for lightweight aerospace systems is critical to the development of modern reusable high-speed platforms. This is particularly challenging to achieve for structures that exhibit higher order local deformations which, when coupled with invsicid-viscous interactions and non-isentropic flow, can lead to significant local variations in the aerodynamic loads. This study is focused on comparing two strategies for computing aerodynamic pressure loads in order to identify an accurate and efficient approach that requires minimal a priori assumptions regarding the structural response. The first strategy relies on parameterization of the structure in terms of a set of characteristic shapes. The characteristic shapes are identified by exciting the structure of interest using a representative load and then extracting the dominant features of the response. The set of characteristic shapes are then used to generate fluid loads from a Reynold's Averaged Navier-Stokes solution. The second strategy relies on approximate fluid models to compute the aerodynamic pressure. The approximate models considered as part of this study include classical piston theory, a local piston theory method where relevant freestream parameters are replaced by spatially local quantities , and an inviscid-viscous interaction model that attempts to account for the presence of the viscous boundary layer over a deformed surface. The various approaches are compared against Reynold's Averaged Navier-Stokes solutions in the context of a two-dimensional compliant panel subject to shock impingement. The results of this study indicate the following: 1) Accurate and efficient parameteriza-tion of the structure using characteristic shapes is possible, assuming that representative loads are used to excite the structure, 2) The pressure is relatively insensitive to reconstruction errors of structural displacements fit to a truncated set of modes, and 3) Approximate fluid models are capable of reasonably accurate and efficient prediction of pressure loads for a compliant panel subject to shock impingement. Nomenclature A Amplitude a Speed of sound C Covariance matrix C f Coefficient of skin friction c Constant D Flexural stiffness E Young's Modulus f Frequency H Boundary layer shape factor h Panel thickness L Panel length M Mach number m Total number of nodes in each snapshot N Total number of snapshots P Fluid pressure P N oise White noise pressure load

@inproceedings{sanchez2016,
	title = {Assessment of the fluid-structure interaction capabilities for aeronautical applications of the open-source solver {SU2}},
	author = {Sanchez, R. and Kline, H. and Thomas, D. and Variyar, A. and Righi, M. and Economon, T. and Alonso, J. and Palacios, R. and Dimitridiadis, G. and Terrapon, V.},
	year = {2016},
}

@article{lemal2016,
	title = {Air {Collisional}-{Radiative} {Modeling} with {Heavy}-{Particle} {Impact} {Excitation} {Processes}},
	volume = {30},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.T4549},
	doi = {10.2514/1.T4549},
	abstract = {This paper reviews the electron- and heavy-particle impact processes governing the population/depletion of the states of N, O, N2, and N2+, which can be significantly affected by nonequilibrium con...},
	number = {1},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Lemal, A. and Jacobs, C. M. and Perrin, M.-Y. and Laux, C. O. and Tran, P. and Raynaud, E.},
	month = feb,
	year = {2016},
	note = {Publisher: American Institute of Aeronautics and Astronautics},
	keywords = {Air Flowing, Boltzmann Constant, Earth, Earth Atmosphere, Einstein Coefficients, Electron Temperature, Franck Condon Principle, Radiative Heating, Shock Layers, Shock Tube},
	pages = {226--239},
}

This paper reviews the electron- and heavy-particle impact processes governing the population/depletion of the states of N, O, N2, and N2+, which can be significantly affected by nonequilibrium con...

@techreport{airforcestudiesboard2016,
	title = {A {Threat} to {America}'s {Global} {Vigilance}, {Reach}, and {Power}: {High}-{Speed} {Maneuvering} {Weapons}},
	author = {{Air Force Studies Board}},
	year = {2016},
}

@article{parish2016,
	title = {A paradigm for data-driven predictive modeling using field inversion and machine learning},
	volume = {305},
	doi = {10.1016/j.jcp.2015.11.012},
	abstract = {We propose a modeling paradigm, termed field inversion and machine learning (FIML), that seeks to comprehensively harness data from sources such as high-fidelity simulations and experiments to aid the creation of improved closure models for computational physics applications. In contrast to inferring model parameters, this work uses inverse modeling to obtain corrective, spatially distributed functional terms, offering a route to directly address model-form errors. Once the inference has been performed over a number of problems that are representative of the deficient physics in the closure model, machine learning techniques are used to reconstruct the model corrections in terms of variables that appear in the closure model. These reconstructed functional forms are then used to augment the closure model in a predictive computational setting. As a first demonstrative example, a scalar ordinary differential equation is considered, wherein the model equation has missing and deficient terms. Following this, the methodology is extended to the prediction of turbulent channel flow. In both of these applications, the approach is demonstrated to be able to successfully reconstruct functional corrections and yield accurate predictive solutions while providing a measure of model form uncertainties.},
	journal = {Journal of Computational Physics},
	author = {Parish, Eric J. and Duraisamy, Karthik},
	year = {2016},
	keywords = {Closure modeling, Data-driven modeling, Machine learning},
	pages = {758--774},
}

We propose a modeling paradigm, termed field inversion and machine learning (FIML), that seeks to comprehensively harness data from sources such as high-fidelity simulations and experiments to aid the creation of improved closure models for computational physics applications. In contrast to inferring model parameters, this work uses inverse modeling to obtain corrective, spatially distributed functional terms, offering a route to directly address model-form errors. Once the inference has been performed over a number of problems that are representative of the deficient physics in the closure model, machine learning techniques are used to reconstruct the model corrections in terms of variables that appear in the closure model. These reconstructed functional forms are then used to augment the closure model in a predictive computational setting. As a first demonstrative example, a scalar ordinary differential equation is considered, wherein the model equation has missing and deficient terms. Following this, the methodology is extended to the prediction of turbulent channel flow. In both of these applications, the approach is demonstrated to be able to successfully reconstruct functional corrections and yield accurate predictive solutions while providing a measure of model form uncertainties.

@article{alauzet2016,
	title = {A decade of progress on anisotropic mesh adaptation for computational fluid dynamics},
	volume = {72},
	issn = {0010-4485},
	doi = {10.1016/j.cad.2015.09.005},
	abstract = {In the context of scientific computing, the mesh is used as a discrete support for the considered numerical methods. As a consequence, the mesh greatly impacts the efficiency, the stability and the accuracy of numerical methods. The goal of anisotropic mesh adaptation is to generate a mesh which fits the application and the numerical scheme in order to achieve the best possible solution. It is thus an active field of research which is progressing continuously. This review article proposes a synthesis of the research activity of the INRIA Gamma3 team in the field of anisotropic mesh adaptation applied to inviscid flows in computational fluid dynamics since 2000. It shows the evolution of the theoretical and numerical results during this period. Finally, challenges for the next decade are discussed.},
	journal = {23rd International Meshing Roundtable Special Issue: Advances in Mesh Generation},
	author = {Alauzet, Frédéric and Loseille, Adrien},
	month = mar,
	year = {2016},
	keywords = {Anisotropic mesh adaptation, Computational fluid dynamic, Continuous mesh framework, Inviscid flows, Metric},
	pages = {13--39},
}

In the context of scientific computing, the mesh is used as a discrete support for the considered numerical methods. As a consequence, the mesh greatly impacts the efficiency, the stability and the accuracy of numerical methods. The goal of anisotropic mesh adaptation is to generate a mesh which fits the application and the numerical scheme in order to achieve the best possible solution. It is thus an active field of research which is progressing continuously. This review article proposes a synthesis of the research activity of the INRIA Gamma3 team in the field of anisotropic mesh adaptation applied to inviscid flows in computational fluid dynamics since 2000. It shows the evolution of the theoretical and numerical results during this period. Finally, challenges for the next decade are discussed.

@article{plane2015,
	title = {The {Mesosphere} and {Metals}: {Chemistry} and {Changes}},
	volume = {115},
	issn = {0009-2665},
	shorttitle = {The {Mesosphere} and {Metals}},
	doi = {10.1021/cr500501m},
	number = {10},
	journal = {Chemical Reviews},
	author = {Plane, John M. C. and Feng, Wuhu and Dawkins, Erin C. M.},
	month = may,
	year = {2015},
	pages = {4497--4541},
}

@inproceedings{bradford2015,
	address = {Oxford, UK},
	title = {Firefly - {New} {Generation} of {Low} {Cost}, {Small} {Launch} {Vehicles} {Designed} to {Serve} the {Rapidly} {Growing} {Small} {Satellite} {Market}},
	doi = {https://doi.org/10.1007/978-3-319-32817-1_5},
	publisher = {Springer},
	author = {Bradford, Andy and Markusic, Tom and Sabripour, Shey},
	month = nov,
	year = {2015},
}

@book{hatton2015,
	title = {Proceedings of the 13th {Reinventing} {Space} {Conference}},
	isbn = {978-3-319-32816-4},
	publisher = {Springer},
	author = {Hatton, Scott},
	month = nov,
	year = {2015},
}

@article{scheiner2015,
	title = {Theory of the electron sheath and presheath},
	volume = {22},
	issn = {1070-664X},
	doi = {10.1063/1.4939024},
	abstract = {Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell (PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions (Te≫Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.},
	number = {12},
	urldate = {2024-04-24},
	journal = {Physics of Plasmas},
	author = {Scheiner, Brett and Baalrud, Scott D. and Yee, Benjamin T. and Hopkins, Matthew M. and Barnat, Edward V.},
	month = dec,
	year = {2015},
	pages = {123520},
}

Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell (PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions (Te≫Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.

@article{ali2015,
	series = {Clean, {Efficient} and {Affordable} {Energy} for a {Sustainable} {Future}: {The} 7th {International} {Conference} on {Applied} {Energy} ({ICAE2015})},
	title = {Numerical {Simulation} of {Turbine} {Blade} {Cooling} via {Jet} {Impingement}},
	volume = {75},
	issn = {1876-6102},
	url = {https://www.sciencedirect.com/science/article/pii/S1876610215014514},
	doi = {10.1016/j.egypro.2015.07.683},
	abstract = {Various industrial applications use jet impingement against surface to provide an effective mode of heat transfer. Its application includes, but not limited to, heat treatment, thermal management of optical surfaces for defogging, cooling of critical machinery structures, and rocket launcher cooling. In this study, numerical analysis of various heat transfer configurations of jet impingement on a semi-circular surface is carried out. These configurations were compared on the basis of effective heat transfer by achieving higher Nusselt number and lower surface temperature as convection heat is becoming the dominant phenomenon. The numerical model was developed for considering the application of a uniform heat flux on a curved surface subjected to jet flow that simulating an internal channel under cooling. The results found to be in agreement with the literature experimental data. To gain more insight on the underlining physics of the flow, a sensitivity analysis on the jet impingement configuration and flow conditions were conducted and was demonstrated to the inner cooling of the 1st stage gas turbine blade.},
	urldate = {2024-04-24},
	journal = {Energy Procedia},
	author = {Ali, Abdulla R. Al and Janajreh, Isam},
	month = aug,
	year = {2015},
	keywords = {Nusselt number, jetcooling, serpantine, turbine blade cooling},
	pages = {3220--3229},
}

Various industrial applications use jet impingement against surface to provide an effective mode of heat transfer. Its application includes, but not limited to, heat treatment, thermal management of optical surfaces for defogging, cooling of critical machinery structures, and rocket launcher cooling. In this study, numerical analysis of various heat transfer configurations of jet impingement on a semi-circular surface is carried out. These configurations were compared on the basis of effective heat transfer by achieving higher Nusselt number and lower surface temperature as convection heat is becoming the dominant phenomenon. The numerical model was developed for considering the application of a uniform heat flux on a curved surface subjected to jet flow that simulating an internal channel under cooling. The results found to be in agreement with the literature experimental data. To gain more insight on the underlining physics of the flow, a sensitivity analysis on the jet impingement configuration and flow conditions were conducted and was demonstrated to the inner cooling of the 1st stage gas turbine blade.

@incollection{zhu_additive_2015,
	title = {Additive {Manufacturing} of {Silicon} {Carbide}-{Based} {Ceramics} {By} 3-{D} {Printing} {Technologies}},
	copyright = {Copyright © 2016 by The American Ceramic Society. All rights reserved.},
	isbn = {978-1-119-21166-2},
	abstract = {Silicon carbide (SiC)-based materials are needed for a number of high temperature applications due to their excellent strength, thermal stability, and oxidation resistance. Fabrication of functional SiC ceramics by additive manufacturing technologies greatly reduces production time and cost, particularly for small production quantities necessary for prototype development. Two approaches which utilize 3-D printing technologies to obtain a SiC ceramic were investigated in this study. Various shapes with engineered porosity were printed using a commercially available wood filament which served as a carbonaceous preform. The printed samples were infiltrated with a pre-ceramic polymer containing dip-coat solution then pyrolyzed. The effect of solution composition on structure retention and conversion to SiC were investigated. In the second approach, pre-ceramic pastes comprised of SiC, silicon (Si), and carbon (C) particulates were evaluated as a potential extruder feedstock. Characteristic decomposition patterns in nitrogen and air were observed using thermogravimetric analysis (TGA), and X-Ray Diffraction (XRD) was used for phase identification. The effect of Si addition, SiC particle size, and pyrolysis conditions on the conversion to SiC has been studied.},
	language = {en},
	urldate = {2023-10-28},
	booktitle = {Advanced {Processing} and {Manufacturing} {Technologies} for {Nanostructured} and {Multifunctional} {Materials} {II}},
	publisher = {John Wiley \& Sons, Ltd},
	author = {Zhu, Shirley X. and Michael, Halbig C. and Mrityunjay, Singh},
	year = {2015},
	keywords = {3-d printing technology, carbide-based ceramic, extruder feedstock, phase identification},
	pages = {133--144},
}

Silicon carbide (SiC)-based materials are needed for a number of high temperature applications due to their excellent strength, thermal stability, and oxidation resistance. Fabrication of functional SiC ceramics by additive manufacturing technologies greatly reduces production time and cost, particularly for small production quantities necessary for prototype development. Two approaches which utilize 3-D printing technologies to obtain a SiC ceramic were investigated in this study. Various shapes with engineered porosity were printed using a commercially available wood filament which served as a carbonaceous preform. The printed samples were infiltrated with a pre-ceramic polymer containing dip-coat solution then pyrolyzed. The effect of solution composition on structure retention and conversion to SiC were investigated. In the second approach, pre-ceramic pastes comprised of SiC, silicon (Si), and carbon (C) particulates were evaluated as a potential extruder feedstock. Characteristic decomposition patterns in nitrogen and air were observed using thermogravimetric analysis (TGA), and X-Ray Diffraction (XRD) was used for phase identification. The effect of Si addition, SiC particle size, and pyrolysis conditions on the conversion to SiC has been studied.

@article{bitter2015,
	title = {Stability of highly cooled hypervelocity boundary layers},
	volume = {778},
	issn = {0022-1120, 1469-7645},
	doi = {10.1017/jfm.2015.358},
	abstract = {The influence of high levels of wall cooling on the stability of hypervelocity boundary layers is investigated. Such conditions are relevant to experiments in high-enthalpy impulse facilities, where the wall temperature is much smaller than the free-stream temperature, as well as to some real flight scenarios. Some effects of wall cooling are well known, for instance, the stabilization of the first mode and destabilization of the second mode. In this paper, several new instability phenomena are investigated that arise only for high Mach numbers and high levels of wall cooling. In particular, certain unstable modes can travel supersonically with respect to the free stream, which changes the nature of the dispersion curve and leads to instability over a much wider band of frequencies. The cause of this phenomenon, the range of parameters for which it occurs and its implications for boundary layer stability are examined. Additionally, growth rates are systematically reported for a wide range of conditions relevant to high-enthalpy impulse facilities, and the stability trends in terms of Mach number and wall temperature are mapped out. Thermal non-equilibrium is included in the analysis and its influence on the stability characteristics of flows in impulse facilities is assessed.},
	language = {en},
	urldate = {2023-08-08},
	journal = {Journal of Fluid Mechanics},
	author = {Bitter, N. P. and Shepherd, J. E.},
	month = sep,
	year = {2015},
	note = {Publisher: Cambridge University Press},
	keywords = {boundary layer stability, compressible flows, transition to turbulence},
	pages = {586--620},
}

The influence of high levels of wall cooling on the stability of hypervelocity boundary layers is investigated. Such conditions are relevant to experiments in high-enthalpy impulse facilities, where the wall temperature is much smaller than the free-stream temperature, as well as to some real flight scenarios. Some effects of wall cooling are well known, for instance, the stabilization of the first mode and destabilization of the second mode. In this paper, several new instability phenomena are investigated that arise only for high Mach numbers and high levels of wall cooling. In particular, certain unstable modes can travel supersonically with respect to the free stream, which changes the nature of the dispersion curve and leads to instability over a much wider band of frequencies. The cause of this phenomenon, the range of parameters for which it occurs and its implications for boundary layer stability are examined. Additionally, growth rates are systematically reported for a wide range of conditions relevant to high-enthalpy impulse facilities, and the stability trends in terms of Mach number and wall temperature are mapped out. Thermal non-equilibrium is included in the analysis and its influence on the stability characteristics of flows in impulse facilities is assessed.

@inproceedings{sanchez2015,
	title = {Towards a fluid-structure interaction solver for problems with large deformations within the open-source {SU2} suite},
	isbn = {978-1-62410-392-6},
	doi = {10.2514/6.2016-0205},
	abstract = {This paper describes a new framework for Fluid-Structure Interaction (FSI) modelling within the open-source code SU2. SU2 has been developed to solve complex, multi-physics problems described by Partial Differential Equations (PDEs), with an emphasis on problems involving aerodynamic shape optimization. Due to its modularity, the code provides an appropriate infrastructure for the solution of physical problems in several disciplines. This work provides SU2 with new tools that expand its capabilities in the fields of structural analysis and FSI. The focus will be on geometrically-nonlinear deformable solids in low-speed external ows. A Finite Element (FE) structural solver, able to deal with geometrical and material non-linearities in a static and a dynamic setting, has been built within the framework of SU2 alongside the existing solvers. Following the original object-oriented architecture in C++, a new structure compliant with the CFD solver has been developed. These new features will serve as a basis for future developments of FE-based strategies for the solution of PDEs. The structural solver has been coupled with the original uid solver in SU2 using a partitioned approach. The structure of the code was fully recast to allow analysis across multiple zones and physical problems, currently limited to problems involving uid and structural analysis. Both loosely-and strongly-coupled strategies are available for the solution of the coupled FSI problem. Finally, the validity of the implementations is assessed by studying the behavior of a rigid square with a exible cantilever at low Reynolds number. The results obtained demonstrate the capabilities of these new developments and further address the physics behind this benchmark problem.},
	publisher = {AIAA Paper 2016-0205},
	author = {Sanchez, Ruben and Palacios, Rafael and Economon, Thomas D. and Kline, Heather L. and Alonso, Juan J. and Palacios, Francisco},
	year = {2015},
}

This paper describes a new framework for Fluid-Structure Interaction (FSI) modelling within the open-source code SU2. SU2 has been developed to solve complex, multi-physics problems described by Partial Differential Equations (PDEs), with an emphasis on problems involving aerodynamic shape optimization. Due to its modularity, the code provides an appropriate infrastructure for the solution of physical problems in several disciplines. This work provides SU2 with new tools that expand its capabilities in the fields of structural analysis and FSI. The focus will be on geometrically-nonlinear deformable solids in low-speed external ows. A Finite Element (FE) structural solver, able to deal with geometrical and material non-linearities in a static and a dynamic setting, has been built within the framework of SU2 alongside the existing solvers. Following the original object-oriented architecture in C++, a new structure compliant with the CFD solver has been developed. These new features will serve as a basis for future developments of FE-based strategies for the solution of PDEs. The structural solver has been coupled with the original uid solver in SU2 using a partitioned approach. The structure of the code was fully recast to allow analysis across multiple zones and physical problems, currently limited to problems involving uid and structural analysis. Both loosely-and strongly-coupled strategies are available for the solution of the coupled FSI problem. Finally, the validity of the implementations is assessed by studying the behavior of a rigid square with a exible cantilever at low Reynolds number. The results obtained demonstrate the capabilities of these new developments and further address the physics behind this benchmark problem.

@inproceedings{berger2015,
	address = {Kissimmee, Florida},
	title = {{NASA} {Langley} {Aerothermodynamics} {Laboratory}: {Hypersonic} {Testing} {Capabilities}},
	isbn = {978-1-62410-343-8},
	shorttitle = {{NASA} {Langley} {Aerothermodynamics} {Laboratory}},
	doi = {10.2514/6.2015-1337},
	language = {en},
	urldate = {2023-08-03},
	booktitle = {53rd {AIAA} {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2015-1337},
	author = {Berger, Karen T. and Hollingsworth, Kevin E. and Wright, Shelia A. and Rufer, Shann J.},
	month = jan,
	year = {2015},
}

@article{chen2015,
	title = {Two-dimensional electron gas at the {Ti}-diffused {BiFeO3}/{SrTiO3} interface},
	volume = {107},
	doi = {10.1063/1.4926732},
	abstract = {Oxide heterostructures with the broken translational symmetry often trigger a two-dimensional quantum confinement and associated unique electronic properties that cannot be observed in bulk constit...},
	number = {3},
	journal = {Applied Physics Letters},
	author = {Chen, Chunlin and Lv, Shuhui and Li, Junjie and Wang, Zhongchang and Liang, Xiaobin and Li, Yanxi and Viehland, Dwight and Nakajima, Ken and Ikuhara, Yuichi},
	month = jul,
	year = {2015},
	note = {Publisher: AIP Publishing LLCAIP Publishing},
	keywords = {ab initio calculations, atomic force microscopy, bismuth compounds, chemical interdiffusion, strontium compounds, transmission electron microscopy, two-dimensional electron gas, valence bands},
	pages = {031601--031601},
}

Oxide heterostructures with the broken translational symmetry often trigger a two-dimensional quantum confinement and associated unique electronic properties that cannot be observed in bulk constit...

@article{burnaev2015,
	title = {Surrogate modeling of multifidelity data for large samples},
	volume = {60},
	url = {https://link.springer.com/article/10.1134/S1064226915120037},
	doi = {10.1134/S1064226915120037},
	abstract = {The problem of construction of a surrogate model based on available lowand high-fidelity data is considered. The low-fidelity data can be obtained, e.g., by performing the computer simulation and the high-fidelity data can be obtained by performing experiments in a wind tunnel. A regression model based on Gaussian processes proves to be convenient for modeling variable-fidelity data. Using this model, one can efficiently reconstruct nonlinear dependences and estimate the prediction accuracy at a specified point. However, if the sample size exceeds several thousand points, direct use of the Gaussian process regression becomes impossible due to a high computational complexity of the algorithm. We develop new algorithms for processing multifidelity data based on Gaussian process model, which are efficient even for large samples. We illustrate application of the developed algorithms by constructing surrogate models of a complex engineering system.},
	number = {12},
	journal = {Journal of Communications Technology and Electronics 2015 60:12},
	author = {Burnaev, E. V. and Zaytsev, A. A.},
	month = dec,
	year = {2015},
	note = {Publisher: Springer},
	keywords = {Communications Engineering, Networks},
	pages = {1348--1355},
}

The problem of construction of a surrogate model based on available lowand high-fidelity data is considered. The low-fidelity data can be obtained, e.g., by performing the computer simulation and the high-fidelity data can be obtained by performing experiments in a wind tunnel. A regression model based on Gaussian processes proves to be convenient for modeling variable-fidelity data. Using this model, one can efficiently reconstruct nonlinear dependences and estimate the prediction accuracy at a specified point. However, if the sample size exceeds several thousand points, direct use of the Gaussian process regression becomes impossible due to a high computational complexity of the algorithm. We develop new algorithms for processing multifidelity data based on Gaussian process model, which are efficient even for large samples. We illustrate application of the developed algorithms by constructing surrogate models of a complex engineering system.

@article{martin2015,
	title = {Strongly {Coupled} {Computation} of {Material} {Response} and {Nonequilibrium} {Flow} for {Hypersonic} {Ablation}},
	volume = {52},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.A32847},
	doi = {10.2514/1.A32847},
	abstract = {The steps necessary to achieve the strong coupling between a flowfield solver and a material response solver are presented. This type of coupling is required to accurately capture the complex aerot...},
	number = {1},
	journal = {Journal of Spacecraft and Rockets},
	author = {Martin, Alexandre and Boyd, Iain D.},
	month = feb,
	year = {2015},
	note = {Publisher: American Institute of Aeronautics and Astronautics},
	keywords = {Arbitrary Lagrangian Eulerian, Boundary Layer, Courant Friedrichs Lewy, Freestream Mach Number, Heat Flux, Hypersonic Ablation, Hypersonic Aerothermodynamics, Nonequilibrium Flows, Pyrolysis, Stagnation Point},
	pages = {89--104},
}

The steps necessary to achieve the strong coupling between a flowfield solver and a material response solver are presented. This type of coupling is required to accurately capture the complex aerot...

@inproceedings{luquet2015,
	title = {Sonic {Boom} {Assessment} of a {Hypersonic} {Transport} {Vehicle} with {Advanced} {Numerical} {Methods}},
	doi = {10.2514/6.2015-2685},
	publisher = {\{AIAA Paper\} 2015-2685},
	author = {Luquet, David and Marchiano, Régis and Coulouvrat, François and Salah El Din, Itham and Loseille, Adrien},
	year = {2015},
	pages = {1--13},
}

@article{gaitonde2015,
	title = {Progress in shock wave/boundary layer interactions},
	volume = {72},
	issn = {0376-0421},
	url = {https://www.sciencedirect.com/science/article/pii/S0376042114000815},
	doi = {10.1016/j.paerosci.2014.09.002},
	abstract = {Recent advances in shock wave boundary layer interaction research are reviewed in four areas: (i) understanding low frequency unsteadiness, (ii) heat transfer prediction capability, (iii) phenomena in complex (multi-shock boundary layer) interactions and (iv) flow control techniques. Substantial success has been achieved in describing the phenomenology of low frequency unsteadiness, including correlations and coherent structures in the separation bubble, through complementary experimental and numerical studies on nominally 2-D interactions. These observations have been parlayed to propose underlying mechanisms based on oscillation, amplification and upstream boundary layer effects. For heat transfer prediction capability, systematic studies conducted under the auspices of AFOSR and RTO-AVT activities have shown that for axisymmetric laminar situations, heat transfer rates can be measured, and in many cases predicted, reasonably accurately even in the presence of high-temperature effects. Efforts have quantified uncertainty of Reynolds averaged turbulence models, and hybrid methods have been developed to at least partially address deficiencies. Progress in complex interactions encompass two of the major phenomena affected by SBLI in scramjet flowpaths: unstart and mode transition from ramjet (dual mode) to scramjet. Control studies have attempted to leverage the better understanding of the fundamental phenomena with passive and active techniques, the latter exploiting the superior properties of newer actuators. Objectives include reduction in size of the separation region, surface loads and modulation of spectral content. Finally, SBLI studies have benefited handsomely from successful ground and flight test campaigns associated with the HIFiRE-1 and HIFiRE-2 campaigns, results from which are woven into the discussion, as are limitations in current capability and understanding.},
	journal = {Celebrating 60 Years of the Air Force Office of Scientific Research (AFOSR): A Review of Hypersonic Aerothermodynamics},
	author = {Gaitonde, Datta V.},
	month = jan,
	year = {2015},
	keywords = {Separated flows, Shock boundary layer interactions, Viscous–inviscid interactions},
	pages = {80--99},
}

Recent advances in shock wave boundary layer interaction research are reviewed in four areas: (i) understanding low frequency unsteadiness, (ii) heat transfer prediction capability, (iii) phenomena in complex (multi-shock boundary layer) interactions and (iv) flow control techniques. Substantial success has been achieved in describing the phenomenology of low frequency unsteadiness, including correlations and coherent structures in the separation bubble, through complementary experimental and numerical studies on nominally 2-D interactions. These observations have been parlayed to propose underlying mechanisms based on oscillation, amplification and upstream boundary layer effects. For heat transfer prediction capability, systematic studies conducted under the auspices of AFOSR and RTO-AVT activities have shown that for axisymmetric laminar situations, heat transfer rates can be measured, and in many cases predicted, reasonably accurately even in the presence of high-temperature effects. Efforts have quantified uncertainty of Reynolds averaged turbulence models, and hybrid methods have been developed to at least partially address deficiencies. Progress in complex interactions encompass two of the major phenomena affected by SBLI in scramjet flowpaths: unstart and mode transition from ramjet (dual mode) to scramjet. Control studies have attempted to leverage the better understanding of the fundamental phenomena with passive and active techniques, the latter exploiting the superior properties of newer actuators. Objectives include reduction in size of the separation region, surface loads and modulation of spectral content. Finally, SBLI studies have benefited handsomely from successful ground and flight test campaigns associated with the HIFiRE-1 and HIFiRE-2 campaigns, results from which are woven into the discussion, as are limitations in current capability and understanding.

@article{liechty2015,
	title = {Object-oriented/data-oriented design of a direct simulation {Monte} {Carlo} algorithm},
	volume = {52},
	url = {https://arc.aiaa.org/doi/10.2514/1.A33177},
	doi = {10.2514/1.A33177/ASSET/IMAGES/LARGE/FIGURE8.JPEG},
	abstract = {National Aeronautics and Space Administration has been investing in the development of a new code, the Multiphysics Algorithm with Particles, to incorporate recent developments in direct simulation Monte Carlo algorithms and improve physical realism, time to solution, and expand the range of usefulness of National Aeronautics and Space Administration direct simulation Monte Carlo codes (in both velocity space and altitude). The Multiphysics Algorithm with Particles is an object-oriented/data-oriented code written in C++. Object-oriented codes are likely the most flexible and efficient approach for the development of new algorithms and physics modules due to their inherent modularity. However, computational efficiency is an equally critical component of software design that must be considered, which is why data-oriented design becomes important. The focus of the development of the Multiphysics Algorithm with Particles thus far has been on the creation of efficient particle data structures, the inclusion of gas models, and the ability to dynamically adapt a simulation. Future work will focus on more efficient grid structures and parallel computing strategies. The new software is evaluated in the current study with regard to 1) software design and extensibility, 2) accuracy of solution, and 3) efficiency of solution. For each category, comparisons will be made against legacy software to identify the relative merits of each software package. For software design and extensibility, the details of the Software Engineering Plan for the Multiphysics Algorithm with Particles will be presented. For accuracy of solution, comparisons will be made to test cases from the literature. Speed comparisons are made between the Multiphysics Algorithm with Particles and the current production direct simulation Monte Carlo code at National Aeronautics and Space Administration, the direct simulation Monte Carlo Analysis Code, for both serial and parallel implementations. More importantly, though, are the automated grid, time step, and surface temperature adaptation algorithms included in the Multiphysics Algorithm with Particles. The user can now specify the simulation initial conditions and begin the solution one time, and the Multiphysics Algorithm with Particles automatically adapts the solution and determines when the final solution has been reached.},
	number = {6},
	journal = {Journal of Spacecraft and Rockets},
	author = {Liechty, Derek S.},
	month = oct,
	year = {2015},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {C++ Programming Language, Data Structures, Direct Simulation Monte Carlo, Freestream, Knudsen Numbers, NASA Langley Research Center, National Aeronautics and Space Administration, Number of Particles, Parallel Computing Strategies, Software Design‎},
	pages = {1521--1529},
}

National Aeronautics and Space Administration has been investing in the development of a new code, the Multiphysics Algorithm with Particles, to incorporate recent developments in direct simulation Monte Carlo algorithms and improve physical realism, time to solution, and expand the range of usefulness of National Aeronautics and Space Administration direct simulation Monte Carlo codes (in both velocity space and altitude). The Multiphysics Algorithm with Particles is an object-oriented/data-oriented code written in C++. Object-oriented codes are likely the most flexible and efficient approach for the development of new algorithms and physics modules due to their inherent modularity. However, computational efficiency is an equally critical component of software design that must be considered, which is why data-oriented design becomes important. The focus of the development of the Multiphysics Algorithm with Particles thus far has been on the creation of efficient particle data structures, the inclusion of gas models, and the ability to dynamically adapt a simulation. Future work will focus on more efficient grid structures and parallel computing strategies. The new software is evaluated in the current study with regard to 1) software design and extensibility, 2) accuracy of solution, and 3) efficiency of solution. For each category, comparisons will be made against legacy software to identify the relative merits of each software package. For software design and extensibility, the details of the Software Engineering Plan for the Multiphysics Algorithm with Particles will be presented. For accuracy of solution, comparisons will be made to test cases from the literature. Speed comparisons are made between the Multiphysics Algorithm with Particles and the current production direct simulation Monte Carlo code at National Aeronautics and Space Administration, the direct simulation Monte Carlo Analysis Code, for both serial and parallel implementations. More importantly, though, are the automated grid, time step, and surface temperature adaptation algorithms included in the Multiphysics Algorithm with Particles. The user can now specify the simulation initial conditions and begin the solution one time, and the Multiphysics Algorithm with Particles automatically adapts the solution and determines when the final solution has been reached.

@article{henneton2015,
	title = {Numerical {Simulation} of {Sonic} {Boom} from {Hypersonic} {Meteoroids}},
	volume = {53},
	url = {http://arc.aiaa.org/doi/10.2514/1.J053421},
	doi = {10.2514/1.J053421},
	abstract = {Meteoroids entering the Earth atmosphere at high hypersonic velocities are sources of sonic booms that are recorded as infrasound signals at the ground level. The boom pressure field is simulated by solving Euler equations for a spherical meteoroid. The numerical challenge is to capture the acoustical regime of weak shock waves in the very far field at several hundreds or thousands times the meteoroid diameter. Computational fluid dynamics simulations are then matched to nonlinear geometrical acoustics for long-range atmospheric propagation down to the ground. The numerical process is validated through comparison with an analytical model, considering for perfect gases the meteoroid as a line source of strong shock in the near field, matched to a weak shock N-wave in the far field. Compared with a perfect gas, real gas effects at thermochemical equilibrium induce a reduced amplitude at the source, along with a shorter signal duration at the ground level. Simulations are illustrated for the well-documented Carancas meteorite that impacted on Peru in 2007.},
	number = {9},
	journal = {AIAA Journal},
	author = {Henneton, Martin and Gainville, Olaf and Coulouvrat, François},
	month = sep,
	year = {2015},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	pages = {2560--2570},
}

Meteoroids entering the Earth atmosphere at high hypersonic velocities are sources of sonic booms that are recorded as infrasound signals at the ground level. The boom pressure field is simulated by solving Euler equations for a spherical meteoroid. The numerical challenge is to capture the acoustical regime of weak shock waves in the very far field at several hundreds or thousands times the meteoroid diameter. Computational fluid dynamics simulations are then matched to nonlinear geometrical acoustics for long-range atmospheric propagation down to the ground. The numerical process is validated through comparison with an analytical model, considering for perfect gases the meteoroid as a line source of strong shock in the near field, matched to a weak shock N-wave in the far field. Compared with a perfect gas, real gas effects at thermochemical equilibrium induce a reduced amplitude at the source, along with a shorter signal duration at the ground level. Simulations are illustrated for the well-documented Carancas meteorite that impacted on Peru in 2007.

@inproceedings{neitzel2015,
	address = {Atlanta, GA},
	title = {Nonequilibrium {Modeling} of {Oxygen} in {Reflected} {Shock} {Tube} {Flows}},
	publisher = {\{AIAA Paper\} 2014-2961},
	author = {Neitzel, Kevin J and Kim, Jae Gang and Boyd, Iain D},
	month = jun,
	year = {2015},
}

@article{kundrapu2015,
	title = {Modeling {Radio} {Communication} {Blackout} and {Blackout} {Mitigation} in {Hypersonic} {Vehicles}},
	volume = {52},
	number = {3},
	journal = {Journal of Spacecraft and Rockets},
	author = {Kundrapu, Madhusudhan and Loverich, John and Beckwith, Kristian and Stoltz, Peter and Shashurin, Alexey and Keidar, Michael},
	month = may,
	year = {2015},
	pages = {853--862},
}

@article{kim2015,
	title = {Master {Equation} {Analysis} of {Post} {Normal} {Shock} {Waves} of {Nitrogen}},
	volume = {29},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.T4249},
	doi = {10.2514/1.T4249},
	abstract = {One-dimensional post normal shock flow calculations are carried out using state-of-the-art thermochemical nonequilibrium models. Two-temperature, four-temperature, and electronic master equation co...},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Kim, Jae Gang and Boyd, Iain D.},
	month = feb,
	year = {2015},
	note = {Publisher: American Institute of Aeronautics and Astronautics},
	keywords = {Electron Temperature, Energy Conservation Equation, Freestream Conditions, Hypersonic Speed, NASA Ames Research Center, Normal Shock Wave, Rankine Hugoniot Relation, Spectrum Radiation, Spontaneous Emission, Vibrational Energy},
	pages = {241--252},
}

One-dimensional post normal shock flow calculations are carried out using state-of-the-art thermochemical nonequilibrium models. Two-temperature, four-temperature, and electronic master equation co...

@book{josyula2015a,
	title = {Hypersonic {Nonequilibrium} {Flows}: {Fundamentals} and {Recent} {Advances}},
	publisher = {AIAA},
	editor = {Josyula, Eswar},
	year = {2015},
}

@book{josyula2015,
	title = {Hypersonic {Nonequilibrium} {Flows}: {Fundamentals} and {Recent} {Advances}},
	publisher = {Progress in Astronautics and Aeronautics},
	editor = {Josyula, Eswar},
	year = {2015},
}

@book{josyula2015b,
	title = {Hypersonic {Nonequilibrium} {Flows}: {Fundamentals} and {Recent} {Advances}},
	publisher = {AIAA},
	editor = {Josyula, Eswar},
	year = {2015},
}

@article{andrienko2015,
	title = {High {Fidelity} {Modeling} of {Thermal} {Relaxation} and {Dissociation} of {Oxygen}},
	volume = {27},
	number = {11601},
	journal = {Physics of Fluids},
	author = {Andrienko, D A and Boyd, I D},
	year = {2015},
	pages = {1--25},
}

@article{juliano2015,
	title = {{HIFIRE}-5 {Flight} {Test} {Results}},
	volume = {52},
	doi = {10.2514/1.A33142},
	number = {3},
	journal = {Journal of Spacecraft and Rockets},
	author = {Juliano, Thomas J and Adamczak, David and Kimmel, Roger L},
	year = {2015},
	pages = {650--663},
}

@article{ling2015,
	title = {Evaluation of machine learning algorithms for prediction of regions of high {Reynolds} averaged {Navier} {Stokes} uncertainty},
	volume = {27},
	url = {http://aip.scitation.org/doi/10.1063/1.4927765},
	doi = {10.1063/1.4927765},
	abstract = {Reynolds Averaged Navier Stokes (RANS) models are widely used in industry to predict fluid flows, despite their acknowledged deficiencies. Not only do RANS models often produce inaccurate flow predictions, but there are very limited diagnostics available to assess RANS accuracy for a given flow configuration. If experimental or higher fidelity simulation results are not available for RANS validation, there is no reliable method to evaluate RANS accuracy. This paper explores the potential of utilizing machine learning algorithms to identify regions of high RANS uncertainty. Three different machine learning algorithms were evaluated: support vector machines, Adaboost decision trees, and random forests. The algorithms were trained on a database of canonical flow configurations for which validated direct numerical simulation or large eddy simulation results were available, and were used to classify RANS results on a point-by-point basis as having either high or low uncertainty, based on the breakdown of specific RANS modeling assumptions. Classifiers were developed for three different basic RANS eddy viscosity model assumptions: the isotropy of the eddy viscosity, the linearity of the Boussinesq hypothesis, and the non-negativity of the eddy viscosity. It is shown that these classifiers are able to generalize to flows substantially different from those on which they were trained. Feature selection techniques, model evaluation, and extrapolation detection are discussed in the context of turbulence modeling applications.},
	number = {8},
	journal = {Physics of Fluids},
	author = {Ling, J. and Templeton, J.},
	year = {2015},
	note = {Publisher: American Institute of Physics Inc.},
	keywords = {Navier-Stokes equations, decision trees, extrapolation, feature selection, flow simulation, learning (artificial intelligence), support vector machines, turbulence, viscosity},
}

Reynolds Averaged Navier Stokes (RANS) models are widely used in industry to predict fluid flows, despite their acknowledged deficiencies. Not only do RANS models often produce inaccurate flow predictions, but there are very limited diagnostics available to assess RANS accuracy for a given flow configuration. If experimental or higher fidelity simulation results are not available for RANS validation, there is no reliable method to evaluate RANS accuracy. This paper explores the potential of utilizing machine learning algorithms to identify regions of high RANS uncertainty. Three different machine learning algorithms were evaluated: support vector machines, Adaboost decision trees, and random forests. The algorithms were trained on a database of canonical flow configurations for which validated direct numerical simulation or large eddy simulation results were available, and were used to classify RANS results on a point-by-point basis as having either high or low uncertainty, based on the breakdown of specific RANS modeling assumptions. Classifiers were developed for three different basic RANS eddy viscosity model assumptions: the isotropy of the eddy viscosity, the linearity of the Boussinesq hypothesis, and the non-negativity of the eddy viscosity. It is shown that these classifiers are able to generalize to flows substantially different from those on which they were trained. Feature selection techniques, model evaluation, and extrapolation detection are discussed in the context of turbulence modeling applications.

@inproceedings{uribarri2015,
	address = {Glasgow, Scotland},
	title = {Electron {Transpiration} {Cooling} for {Hot} {Aerospace} {Surfaces}},
	publisher = {\{AIAA Paper\} 2015-3674},
	author = {Uribarri, Luke A and Allen, Edward H},
	month = jul,
	year = {2015},
	keywords = {etc},
}

@inproceedings{hanquist2015b,
	title = {Comparisons of computations with experiments for electron transpiration cooling at high enthalpies},
	doi = {10.2514/6.2015-2351},
	abstract = {A modeling approach for electron transpiration cooling of high enthalpy ight is compared to a set of experiments performed in a plasma arc tunnel for nitrogen and argon. The comparisons include nitrogen and argon ow at high enthalpies, 12,000 btu/lb and 5,000 btu/lb respectively, with a Mach number of 2.5 to 3. Converting the provided enthalpies and Mach numbers to freestream temperatures and velocities is discussed. The numerical approach is described including implementation of a thermionic emission boundary condition. Also described is the implementation of a finite-rate chemistry model for argon ionization. Different emissive materials are also investigated including graphite and tungsten. The comparisons include two different geometries with different leading edge radii. The numerical results produce a wide range of emitted current due to the uncertainties in freestream conditions and emissive material properties, but still agree well with the experiments. Future work recommendations are provided that may improve the physical accuracy of the modeling capabilities used in the comparisons.},
	booktitle = {45th {AIAA} {Thermophysics} {Conference}},
	publisher = {AIAA Paper 2015-2351},
	author = {Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2015},
	keywords = {etc, own, ★},
	pages = {1--13},
}

A modeling approach for electron transpiration cooling of high enthalpy ight is compared to a set of experiments performed in a plasma arc tunnel for nitrogen and argon. The comparisons include nitrogen and argon ow at high enthalpies, 12,000 btu/lb and 5,000 btu/lb respectively, with a Mach number of 2.5 to 3. Converting the provided enthalpies and Mach numbers to freestream temperatures and velocities is discussed. The numerical approach is described including implementation of a thermionic emission boundary condition. Also described is the implementation of a finite-rate chemistry model for argon ionization. Different emissive materials are also investigated including graphite and tungsten. The comparisons include two different geometries with different leading edge radii. The numerical results produce a wide range of emitted current due to the uncertainties in freestream conditions and emissive material properties, but still agree well with the experiments. Future work recommendations are provided that may improve the physical accuracy of the modeling capabilities used in the comparisons.

@techreport{omidy2015,
	title = {Code-to-{Code} {Comparison}, and {Material} {Response} {Modeling} of {Stardust} and {MSL} using {PATO} and {FIAT}},
	author = {Omidy, Ali D and Panerai, Francesco and Martin, Alexandre and Lachaud, Jean R and Cozmuta, Ioana and Mansour, Nagi N},
	year = {2015},
}

@article{bender2015,
	title = {An improved potential energy surface and multi-temperature quasiclassical trajectory calculations of \{{N}{\textbackslash}textsubscript\{2\} + {N}{\textbackslash}textsubscript\{2\}\} dissociation reactions},
	volume = {143},
	doi = {10.1063/1.4927571},
	number = {5},
	journal = {The Journal of Chemical Physics},
	author = {Bender, Jason D and Valentini, Paolo and Nompelis, Ioannis and Paukku, Yuliya and Varga, Zoltan and Truhlar, Donald G and Schwartzentruber, Thomas E and Candler, Graham V},
	year = {2015},
}

@article{ferlauto2015,
	title = {A {Pseudo}-{Compressibility} {Method} for {Solving} {Inverse} {Problems} based on the {3D} {Incompressible} {Euler} {Equations}},
	journal = {Inverse Problems in Science and Engineering},
	author = {Ferlauto, M.},
	year = {2015},
}

@article{rand2015,
	title = {A {Calcium} {Aluminate} {Electride} {Hollow} {Cathode}},
	volume = {43},
	number = {1},
	journal = {IEEE Transactions on Plasma Science},
	author = {Rand, L P and Williams, J D},
	year = {2015},
	pages = {190--194},
}

@article{kim2014,
	title = {Thermochemical nonequilibrium analysis of {O}$_{\textrm{2}}$-{Ar} based on state-resolved kinetics},
	volume = {446},
	journal = {Chemical Physics},
	author = {Kim, J G and Boyd, I D},
	year = {2014},
	pages = {76--85},
}

@inproceedings{groves2014a,
	address = {National Harbor, Maryland},
	title = {Computational {Fluid} {Dynamics} {Uncertainty} {Analysis} for {Payload} {Fairing} {Spacecraft} {Environmental} {Control} {Systems}},
	doi = {10.2514/6.2014-0440},
	language = {en},
	urldate = {2024-04-01},
	booktitle = {52nd {Aerospace} {Sciences} {Meeting}},
	publisher = {AIAA Paper 2014-0440},
	author = {Groves, Curtis E. and Ilie, Marcel and Schallhorn, Paul},
	month = jan,
	year = {2014},
}

@phdthesis{groves2014,
	address = {Orlando},
	title = {Computational {Fluid} {Dynamics} {Uncertainty} {Analysis} for {Payload} {Fairing} {Spacecraft} {Environmental} {Control} {Systems}},
	language = {en},
	urldate = {2024-03-27},
	school = {University of Central Florida},
	author = {Groves, Curtis E.},
	year = {2014},
}

@book{bansal2014ceramic,
	title = {Ceramic matrix composites: materials, modeling and technology},
	publisher = {John Wiley \& Sons},
	author = {Bansal, Narottam P and Lamon, Jacques},
	year = {2014},
}

@phdthesis{wiebenga2014,
	address = {Ann Arbor},
	title = {High-{Fidelity} {Material} {Response} {Modeling} as {Part} of an {Aerothermoelastic} {Framework} for {Hypersonic} {Flows}},
	school = {University of Michigan},
	author = {Wiebenga, Jonathan},
	year = {2014},
}

@article{lamorte2014,
	title = {Uncertainty {Propagation} in {Hypersonic} {Aerothermoelastic} {Analysis}},
	volume = {51},
	issn = {0021-8669},
	doi = {10.2514/1.C032233},
	abstract = {A framework for uncertainty propagation in hypersonic aeroelastic and aerothermoelastic analyses is presented. First, the aeroelastic stability of a typical section representative of a control surface on a hypersonic vehicle is examined. Variability in the uncoupled natural frequencies of the system is modeled using beta probability distributions. Uncertainty in the flutter Mach number is computed using stochastic collocation. Next, the stability of an aerodynamically heated panel representing a component of the skin of a hypersonic vehicle is considered. In this case, uncertainty is due to the location of transition from laminar to turbulent flow and the heat flux prediction. The effect of propagating these uncertainties on vehicle behavior is determined. For both cases, uncertainty is treated using stochastic collocation, which is a new and effective approach for incorporating uncertainty in this class of problems.},
	number = {1},
	urldate = {2023-08-03},
	journal = {Journal of Aircraft},
	author = {Lamorte, Nicolas and Friedmann, Peretz P. and Glaz, Bryan and Culler, Adam J. and Crowell, Andrew R. and McNamara, Jack J.},
	year = {2014},
	pages = {192--203},
}

A framework for uncertainty propagation in hypersonic aeroelastic and aerothermoelastic analyses is presented. First, the aeroelastic stability of a typical section representative of a control surface on a hypersonic vehicle is examined. Variability in the uncoupled natural frequencies of the system is modeled using beta probability distributions. Uncertainty in the flutter Mach number is computed using stochastic collocation. Next, the stability of an aerodynamically heated panel representing a component of the skin of a hypersonic vehicle is considered. In this case, uncertainty is due to the location of transition from laminar to turbulent flow and the heat flux prediction. The effect of propagating these uncertainties on vehicle behavior is determined. For both cases, uncertainty is treated using stochastic collocation, which is a new and effective approach for incorporating uncertainty in this class of problems.

@techreport{nemec2014,
	title = {Toward {Automatic} {Verification} of {Goal}-{Oriented} {Flow} {Simulations}},
	url = {https://ntrs.nasa.gov/citations/20150000864},
	author = {Nemec, Marian and Aftosmis, Michael J},
	year = {2014},
}

@techreport{nemec2014a,
	title = {Toward {Automatic} {Verification} of {Goal}-{Oriented} {Flow} {Simulations}},
	url = {https://ntrs.nasa.gov/citations/20150000864},
	author = {Nemec, Marian and Aftosmis, Michael J},
	year = {2014},
}

@techreport{maglieri2014,
	title = {Sonic {Boom}: {Six} {Decades} of {Research}},
	url = {https://ntrs.nasa.gov/citations/20150006843},
	author = {Maglieri, Domenic J and Bobbitt, Percy J and Plotkin, Kenneth J and Shepherd, Kevin P and Coen, Peter G and Richwine, David M},
	year = {2014},
}

@inproceedings{lachaud2014,
	title = {Porous-material analysis toolbox based on openfoam and applications},
	volume = {28},
	url = {http://arc.aiaa.org},
	doi = {10.2514/1.T4262},
	abstract = {The Porous-material Analysis Toolbox based on OpenFOAM is a fully portable OpenFOAM library. It isimplemented to test innovative multiscale physics-based models for reacting porous materials that undergo recession.Current developments are focused on ablative materials. The ablative material response module implemented in the Porous-material Analysis Toolbox relies on an original high-fidelity ablation model. The governing equations are volume-averaged forms of the conservation equations for gas mass, gas species, solid mass, gas momentum, and total energy. It may also simply be used as a state-of-the-art ablation model when the right model options are chosen. As applications, three physical analyses are presented: 1) volume-averaged study of the oxidation of a carbon-fiber preform under dry air, 2) three-dimensional analysis of the pyrolysis gas flow in a porous ablative material sample facing an arcjet, and 3) comparison of a state-of-the-art and a high-fidelity model for the thermal and chemical response of a carbon/phenolic ablative material. © 2013 by the American Institute of Aeronautics and Astronautics, Inc.},
	publisher = {American Institute of Aeronautics and Astronautics Inc.},
	author = {Lachaud, Jean and Mansour, Nagi N.},
	month = apr,
	year = {2014},
	note = {Issue: 2},
	keywords = {Ablative Materials, Chemical Equilibrium, Conservation Equations, Conservation of Mass, Convective Boundary Condition, Diffusion Coefficient, Energy Transfer, Forced Convection, Porous Materials, Pyrolysis Gas Flow},
	pages = {191--202},
}

The Porous-material Analysis Toolbox based on OpenFOAM is a fully portable OpenFOAM library. It isimplemented to test innovative multiscale physics-based models for reacting porous materials that undergo recession.Current developments are focused on ablative materials. The ablative material response module implemented in the Porous-material Analysis Toolbox relies on an original high-fidelity ablation model. The governing equations are volume-averaged forms of the conservation equations for gas mass, gas species, solid mass, gas momentum, and total energy. It may also simply be used as a state-of-the-art ablation model when the right model options are chosen. As applications, three physical analyses are presented: 1) volume-averaged study of the oxidation of a carbon-fiber preform under dry air, 2) three-dimensional analysis of the pyrolysis gas flow in a porous ablative material sample facing an arcjet, and 3) comparison of a state-of-the-art and a high-fidelity model for the thermal and chemical response of a carbon/phenolic ablative material. © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

@article{martin2014,
	title = {Modeling of {Heat} {Transfer} {Attenuation} by {Ablative} {Gases} {During} the {Stardust} {Reentry}},
	volume = {29},
	url = {http://arc.aiaa.org},
	doi = {10.2514/1.T4202},
	abstract = {Modern space vehicles designed for planetary exploration use ablative materials to protect the payload against the high heating environment experienced during reentry. To properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. The present study aims to examine the effects of the blowing of ablation gas in the outer flow field. Using six points on the Stardust entry trajectory at the beginning of the continuum regime, from 81 to 69 km, the various components of the heat flux are compared to air-only solutions. Although an additional component of the heat flux is introduced by mass diffusion, this additional term is mainly balanced by the fact that the translational-rotational component of the heat flux, the main contributor, is greatly reduced. Although a displacement of the shock is observed, it is believed that the most prominent effects are caused by a modification of the chemical composition of the boundary layer, which reduces the gas-phase thermal conductivity. Nomenclature B 0 = nondimensional ablation rate C = vector of source terms D = mass diffusion coefficient, m 2 ∕s E = energy, J∕m 3 e = energy, J∕kg F = inviscid flux matrix F d = diffusive flux matrix h = species enthalpy vector, J∕kg I = identity matrix J = directional species diffusion, kg∕m 2 · s† Kn = Knudsen number k = thermal conductivity, W∕m · K† \_ m 0 0 = mass flow rate, kg∕m 2 · s† p = pressure, Pa Q = vector of conserved variables q = heat flux, W∕m 2 T = temperature, K U, v = velocity, m∕s \_ w = mass source term, kg∕m 3 · s† \_ w v = vibrational energy relaxation source term, J∕m 3 · s† Y = mass fraction, kg∕kg η = distance normal to the wall, m ρ = mass density, kg∕m 3 τ = viscous tensor, Pa Subscripts c = char g = gas blown nc = next to the wall s = species t = time tr = translational-rotational ve = vibrational-electron-electronic w = wall ∞ = freestream},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Martin, Alexandre and Boyd, Iain D},
	year = {2014},
}

Modern space vehicles designed for planetary exploration use ablative materials to protect the payload against the high heating environment experienced during reentry. To properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. The present study aims to examine the effects of the blowing of ablation gas in the outer flow field. Using six points on the Stardust entry trajectory at the beginning of the continuum regime, from 81 to 69 km, the various components of the heat flux are compared to air-only solutions. Although an additional component of the heat flux is introduced by mass diffusion, this additional term is mainly balanced by the fact that the translational-rotational component of the heat flux, the main contributor, is greatly reduced. Although a displacement of the shock is observed, it is believed that the most prominent effects are caused by a modification of the chemical composition of the boundary layer, which reduces the gas-phase thermal conductivity. Nomenclature B 0 = nondimensional ablation rate C = vector of source terms D = mass diffusion coefficient, m 2 ∕s E = energy, J∕m 3 e = energy, J∕kg F = inviscid flux matrix F d = diffusive flux matrix h = species enthalpy vector, J∕kg I = identity matrix J = directional species diffusion, kg∕m 2 · s† Kn = Knudsen number k = thermal conductivity, W∕m · K† _ m 0 0 = mass flow rate, kg∕m 2 · s† p = pressure, Pa Q = vector of conserved variables q = heat flux, W∕m 2 T = temperature, K U, v = velocity, m∕s _ w = mass source term, kg∕m 3 · s† _ w v = vibrational energy relaxation source term, J∕m 3 · s† Y = mass fraction, kg∕kg η = distance normal to the wall, m ρ = mass density, kg∕m 3 τ = viscous tensor, Pa Subscripts c = char g = gas blown nc = next to the wall s = species t = time tr = translational-rotational ve = vibrational-electron-electronic w = wall ∞ = freestream

@techreport{rosema2014,
	address = {AFRL-RQ-WP-TR-2014-0281},
	title = {{MISSILE} {DATA} {COMPENDIUM} ({DATCOM}) {User} {Manual}-2014 {Revision}},
	url = {http://www.dtic.mil},
	author = {Rosema, Christopher and Doyle, Joshua and Blake, William B},
	year = {2014},
}

@article{owen2014,
	title = {Measurements of {Vibrational} {Relaxation} and {Dissociation} of {Oxygen} with {Laser} {Absorption} {Spectroscopy} with {Applications} for {Energy} {Transfer} in {Nonequilibrium} {Air}},
	author = {Owen, K},
	year = {2014},
	note = {Place: Stanford},
}

@inproceedings{marineau2014,
	address = {Atlanta, GA},
	title = {Mach 10 {Boundary}-{Layer} {Transition} {Experiments} on {Sharp} and {Blunted} {Cones}},
	publisher = {\{AIAA Paper\} 2014-3108},
	author = {Marineau, Eric C and Moraru, C George and Lewis, Daniel R and Norris, Joseph D and Lafferty, John F},
	year = {2014},
}

@article{clemens2014,
	title = {Low-{Frequency} {Unsteadiness} of {Shock} {Wave}/{Turbulent} {Boundary} {Layer} {Interactions}},
	volume = {46},
	issn = {0066-4189},
	doi = {10.1146/annurev-fluid-010313-141346},
	abstract = {Shock wave/boundary layer interactions occur in a wide range of supersonic internal and external flows, and often these interactions are associated with turbulent boundary layer separation. The resulting separated flow is associated with large-scale, low-frequency unsteadiness whose cause has been the subject of much attention and debate. In particular, some researchers have concluded that the source of low-frequency motions is in the upstream boundary layer, whereas others have argued for a downstream instability as the driving mechanism. Owing to substantial recent activity, we are close to developing a comprehensive understanding, albeit only in simplified flow configurations. A plausible model is that the interaction responds as a dynamical system that is forced by external disturbances. The low-frequency dynamics seem to be adequately described by a recently proposed shear layer entrainment-recharge mechanism. Upstream boundary layer fluctuations seem to be an important source of disturbances, but the evidence suggests that their impact is reduced with increasing size of the separated flow.},
	number = {1},
	urldate = {2023-01-12},
	journal = {Annual Review of Fluid Mechanics},
	author = {Clemens, Noel T. and Narayanaswamy, Venkateswaran},
	month = jan,
	year = {2014},
	note = {Publisher: Annual Reviews},
	pages = {469--492},
}

Shock wave/boundary layer interactions occur in a wide range of supersonic internal and external flows, and often these interactions are associated with turbulent boundary layer separation. The resulting separated flow is associated with large-scale, low-frequency unsteadiness whose cause has been the subject of much attention and debate. In particular, some researchers have concluded that the source of low-frequency motions is in the upstream boundary layer, whereas others have argued for a downstream instability as the driving mechanism. Owing to substantial recent activity, we are close to developing a comprehensive understanding, albeit only in simplified flow configurations. A plausible model is that the interaction responds as a dynamical system that is forced by external disturbances. The low-frequency dynamics seem to be adequately described by a recently proposed shear layer entrainment-recharge mechanism. Upstream boundary layer fluctuations seem to be an important source of disturbances, but the evidence suggests that their impact is reduced with increasing size of the separated flow.

@article{wang2014,
	title = {High-order computational fluid dynamics tools for aircraft design},
	volume = {372},
	doi = {10.1098/rsta.2013.0318},
	number = {2022},
	urldate = {2023-01-12},
	journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
	author = {Wang, Z. J.},
	month = aug,
	year = {2014},
	note = {Publisher: Royal Society},
	pages = {20130318},
}

@article{deck2014,
	title = {High-fidelity simulations of unsteady civil aircraft aerodynamics: stakes and perspectives. {Application} of zonal detached eddy simulation},
	volume = {372},
	doi = {10.1098/rsta.2013.0325},
	number = {2022},
	urldate = {2023-01-11},
	journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
	author = {Deck, Sébastien and Gand, Fabien and Brunet, Vincent and Ben Khelil, Saloua},
	month = aug,
	year = {2014},
	note = {Publisher: Royal Society},
	pages = {20130325},
}

@book{gudmundsson2014,
	title = {General {Aviation} {Aircraft} {Design}},
	url = {https://doi.org/10.1016/C2011-0-06824-2},
	publisher = {Butterworth-Heinemann},
	author = {Gudmundsson, Snorri},
	year = {2014},
}

@inproceedings{alkandry2014b,
	title = {Conceptual analysis of electron transpiration cooling for the leading edges of hypersonic vehicles},
	doi = {10.2514/6.2014-2674},
	abstract = {Recent progress is presented in an ongoing effort to perform a conceptual analysis of possible electron transpiration cooling using thermo-electric materials at the leading edges of hypersonic vehicles. The implementation of a new boundary condition in the CFD code LeMANS to model the thermionic emission of electrons from the leading edges of hypersonic vehicles is described. A parametric study is performed to understand the effects of the material work function, the freestream velocity, and the leading edge geometry on this cooling effect. The numerical results reveal that lower material work functions, higher freestream velocities, and smaller leading edges can increase the cooling effect due to larger emission current densities. The numerical results also show that the electric field produced by the electron emission may not have a significant effect on the predicted properties. Future work recommendations are provided that may improve the physical accuracy of the modeling capabilities used in this study.},
	booktitle = {11th {AIAA}/{ASME} {Joint} {Thermophysics} and {Heat} {Transfer} {Conference}},
	publisher = {AIAA Paper 2014-2674},
	author = {Alkandry, Hicham and Hanquist, Kyle M. and Boyd, Iain D.},
	year = {2014},
	keywords = {etc, own, ★},
}

Recent progress is presented in an ongoing effort to perform a conceptual analysis of possible electron transpiration cooling using thermo-electric materials at the leading edges of hypersonic vehicles. The implementation of a new boundary condition in the CFD code LeMANS to model the thermionic emission of electrons from the leading edges of hypersonic vehicles is described. A parametric study is performed to understand the effects of the material work function, the freestream velocity, and the leading edge geometry on this cooling effect. The numerical results reveal that lower material work functions, higher freestream velocities, and smaller leading edges can increase the cooling effect due to larger emission current densities. The numerical results also show that the electric field produced by the electron emission may not have a significant effect on the predicted properties. Future work recommendations are provided that may improve the physical accuracy of the modeling capabilities used in this study.

@techreport{adams2014,
	title = {Dakota, {A} {Multilevel} {Parallel} {Object}-{Oriented} {Framework} for {Design} {Optimization}, {Parameter} {Estimation}, {Uncertainty} {Quantification}, and {Sensitivity} {Analysis}: {Version} 6.0 {User}'s {Manual}},
	author = {Adams, B M and Bauman, L E and Bohnhoff, W J and Dalbey, K R and Ebeida, M S and Eddy, J P and Eldred, M S and Hough, P D and Hu, K T and Jakeman, J D and Stephens, J A and Swiler, L P and Vigil, D M and Wildey, T M},
	year = {2014},
	note = {Issue: Sandia Technical Report SAND2014-4633},
}

@inproceedings{maclean2014,
	title = {Comparison {Between} {CFD} and {Measurements} for {Real}-{Gas} {Effects} on {Laminar} {Shock} {Wave} {Boundary} {Layer} {Interaction}, 1},
	publisher = {\{AIAA Paper\} 2014-3366},
	author = {MacLean, M and Holden, M and Dufrene, A},
	year = {2014},
}

@article{schoenenberger2014,
	title = {Assessment of the reconstructed aerodynamics of the mars science laboratory entry vehicle},
	volume = {51},
	url = {https://arc.aiaa.org/doi/10.2514/1.A32794},
	doi = {10.2514/1.A32794/ASSET/IMAGES/LARGE/FIGURE23.JPEG},
	abstract = {On5 August 2012, the Mars Science Laboratory entry vehicle successfully entered the atmosphere of Mars, flying a guided entry until parachute deploy. The Curiosity rover landed safely in Gale crater upon completion of the entry, descent, and landing sequence. Preflight aerodynamic predictions are compared with the aerodynamic performance of the entry capsule identified from onboard flight data, including inertial-measurement-unit accelerometer and rate gyro information, and heat shield surface pressure measurements. From the onboard data, static force and moment coefficients have been extracted. These data are compared with the preflight aerodynamic database. The Mars Science Laboratory flight data represent the most complete and self-consistent record of a blunt capsule entering Mars collected to date. These data enable the separation of aerodynamic performance from atmospheric conditions. The comparisons show the Mars Science Laboratory aerodynamic characteristics have been successfully identified and resolved to an accuracy better than the aerodynamic database uncertainties used in preflight simulations. A number of small anomalies have been identified and are discussed. These data will help improve aerodynamic databases for future missions and will guide computational fluid dynamics development to improve predictions. © 2012 AIAA.},
	number = {4},
	journal = {Journal of Spacecraft and Rockets},
	author = {Schoenenberger, Mark and Van Norman, John and Karlgaard, Chris and Kutty, Prasad and Way, David},
	month = aug,
	year = {2014},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Accelerometer, Aerodynamic Angle, Aerodynamic Force Coefficients, Atmospheric Conditions, CFD Analysis, Flight Software, Mars Science Laboratory, Miniature Inertial Measurement Unit, Pressure Coefficient, Thermal Protection System},
	pages = {1076--1093},
}

On5 August 2012, the Mars Science Laboratory entry vehicle successfully entered the atmosphere of Mars, flying a guided entry until parachute deploy. The Curiosity rover landed safely in Gale crater upon completion of the entry, descent, and landing sequence. Preflight aerodynamic predictions are compared with the aerodynamic performance of the entry capsule identified from onboard flight data, including inertial-measurement-unit accelerometer and rate gyro information, and heat shield surface pressure measurements. From the onboard data, static force and moment coefficients have been extracted. These data are compared with the preflight aerodynamic database. The Mars Science Laboratory flight data represent the most complete and self-consistent record of a blunt capsule entering Mars collected to date. These data enable the separation of aerodynamic performance from atmospheric conditions. The comparisons show the Mars Science Laboratory aerodynamic characteristics have been successfully identified and resolved to an accuracy better than the aerodynamic database uncertainties used in preflight simulations. A number of small anomalies have been identified and are discussed. These data will help improve aerodynamic databases for future missions and will guide computational fluid dynamics development to improve predictions. © 2012 AIAA.

@phdthesis{jewell2014b,
	title = {Boundary-{Layer} {Transition} on a {Slender} {Cone} in {Hypervelocity} {Flow} with {Real} {Gas} {Effects}},
	school = {California Institute of Technology},
	author = {Jewell, Joseph S},
	year = {2014},
}

@article{jewell2014a,
	title = {Boundary-{Layer} {Transition} on a {Slender} {Cone} in {Hypervelocity} {Flow} with {Real} {Gas} {Effects}},
	author = {Jewell, Joseph S},
	year = {2014},
}

@article{jewell2014,
	title = {Boundary-{Layer} {Transition} on a {Slender} {Cone} in {Hypervelocity} {Flow} with {Real} {Gas} {Effects}},
	author = {Jewell, Joseph S},
	month = may,
	year = {2014},
	note = {Place: Pasadena, CA},
}

@inproceedings{vogiatzis2014,
	address = {Montreal, Quebec},
	title = {Aero-thermal simulations of the {TMT} {Laser} {Guide} {Star} {Facility}},
	volume = {9148},
	publisher = {SPIE},
	author = {Vogiatzis, Konstantinos and Boyer, Corinne and Wei, Kai and Tang, Jinlong and Ellerbroek, Brent},
	editor = {Marchetti, Enrico and Close, Laird M and Véran, Jean-Pierre},
	month = aug,
	year = {2014},
	pages = {2024--2033},
}

@misc{delta2013,
	title = {Delta {IV} {Launch} {Services} {User}'s {Guide}},
	url = {https://www.ulalaunch.com/docs/default-source/rockets/delta-iv-user's-guide.pdf},
	month = jun,
	year = {2013},
}

@article{kim2013,
	title = {State-{Resolved} {Master} {Equation} {Analysis} of {Thermochemical} {Nonequilibrium} of {Nitrogen}},
	volume = {415},
	doi = {10.1016/j.chemphys.2013.01.027},
	number = {3},
	journal = {Chemical Physics},
	author = {Kim, J G and Boyd, I D},
	year = {2013},
	pages = {237--246},
}

@book{bijl2013,
	title = {Uncertainty {Quantification} in {Computational} {Fluid} {Dynamics}},
	isbn = {978-3-319-00884-4},
	language = {English},
	publisher = {Springer},
	author = {Bijl, Hester and Lucor, Didier and Mishra, Siddhartha and Schwab, Christoph},
	year = {2013},
}

@phdthesis{lamorte2013,
	address = {Ann Arbor},
	title = {Uncertainty {Propagation} in {Hypersonic} {Vehicle} {Aerothermoelastic} {Analysis}},
	school = {University of Michigan},
	author = {Lamorte, Nicolas},
	year = {2013},
}

@inproceedings{rondeau2013,
	title = {X-{51A} {Scramjet} {Demostrator} {Program}: {Waverider} {Ground} and {Flight} {Test},},
	author = {Rondeau, Christopher M and Jorris, Timothy R},
	year = {2013},
	pages = {1--14},
}

@article{robertson2013,
	title = {Sheaths in laboratory and space plasmas},
	volume = {55},
	doi = {10.1088/0741-3335/55/9/093001},
	abstract = {The sheaths that occur at surfaces in laboratory and space plasmas are reviewed with an emphasis on numerical models that can be solved with modest computational resources. The surfaces in plasma may be the interior walls of confinement devices or inserted probes. Fluid and kinetic models are presented in some detail, and particle-in-cell models are discussed briefly. The numerical methods find the spatial profile of the potential, the particle densities near the surfaces and the current to the surfaces. Maxwellian electrons and cold ions are assumed at the outset and subsequently the models are expanded to encompass (1) multiple electron populations, (2) multiple ion species, (3) finite ion temperature, (4) surfaces that emit electrons such as heated cathodes or emissive probes and (5) surfaces that emit plasma as in the Q-machine. These complications may produce nonmonotonic sheaths in which the first derivative of the potential changes sign or double layers in which the second derivative changes sign. The effect of charge-exchange collisions on ion losses to the wall and on ion current to probes is discussed, but models with collisions of electron are omitted. Some recent advances are discussed, including experiments that measure the ion distribution function in sheaths using laser-induced fluorescence, experiments and numerical models on sheaths with multiple ion species and computational models of sheaths surrounding objects in flowing plasma. © 2013 IOP Publishing Ltd.},
	number = {9},
	journal = {Plasma Physics and Controlled Fusion},
	author = {Robertson, Scott},
	month = jul,
	year = {2013},
	note = {Publisher: IOP Publishing},
}

The sheaths that occur at surfaces in laboratory and space plasmas are reviewed with an emphasis on numerical models that can be solved with modest computational resources. The surfaces in plasma may be the interior walls of confinement devices or inserted probes. Fluid and kinetic models are presented in some detail, and particle-in-cell models are discussed briefly. The numerical methods find the spatial profile of the potential, the particle densities near the surfaces and the current to the surfaces. Maxwellian electrons and cold ions are assumed at the outset and subsequently the models are expanded to encompass (1) multiple electron populations, (2) multiple ion species, (3) finite ion temperature, (4) surfaces that emit electrons such as heated cathodes or emissive probes and (5) surfaces that emit plasma as in the Q-machine. These complications may produce nonmonotonic sheaths in which the first derivative of the potential changes sign or double layers in which the second derivative changes sign. The effect of charge-exchange collisions on ion losses to the wall and on ion current to probes is discussed, but models with collisions of electron are omitted. Some recent advances are discussed, including experiments that measure the ion distribution function in sheaths using laser-induced fluorescence, experiments and numerical models on sheaths with multiple ion species and computational models of sheaths surrounding objects in flowing plasma. © 2013 IOP Publishing Ltd.

@article{farbar2013,
	title = {Numerical {Prediction} of {Hypersonic} {Flowfields} {Including} {Effects} of {Electron} {Translational} {Nonequilibrium}},
	volume = {27},
	number = {4},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Farbar, Erin and Boyd, Iain D and Martin, Alexandre},
	year = {2013},
	pages = {593--606},
}

@article{martins2013,
	title = {Multidisciplinary design optimization: {A} survey of architectures},
	volume = {51},
	url = {http://arc.aiaa.org},
	doi = {10.2514/1.J051895},
	abstract = {Multidisciplinary design optimization is a field of research that studies the application of numerical optimization techniques to the design of engineering systems involving multiple disciplines or components. Since the inception of multidisciplinary design optimization, various methods (architectures) have been developed and applied to solve multidisciplinary design-optimization problems. This paper provides a survey of all the architectures that have been presented in the literature so far. All architectures are explained in detail using a unified description that includes optimization problem statements, diagrams, and detailed algorithms. The diagrams show both data and process flow through the multidisciplinary system and computational elements, which facilitate the understanding of the various architectures, and how they relate to each other. A classification of the multidisciplinary design-optimization architectures based on their problem formulations and decomposition strategies is also provided, and the benefits and drawbacks of the architectures are discussed from both theoretical and experimental perspectives. For each architecture, several applications to the solution of engineering-design problems are cited. The result is a comprehensive but straightforward introduction to multidisciplinary design optimization for nonspecialists and a reference detailing all current multidisciplinary design-optimization architectures for specialists. Copyright © 2013 by the authors.},
	number = {9},
	journal = {AIAA Journal},
	author = {Martins, Joaquim R.R.A. and Lambe, Andrew B.},
	month = sep,
	year = {2013},
	note = {Publisher: American Institute of Aeronautics and Astronautics},
	keywords = {Aerodynamic Loads, Aircraft Design, Computing, Lagrange Multipliers, MDO, Numerical Optimization, Sequential Linear Programming, Sequential Quadratic Programming, Structural Analysis, Structural Optimization},
	pages = {2049--2075},
}

Multidisciplinary design optimization is a field of research that studies the application of numerical optimization techniques to the design of engineering systems involving multiple disciplines or components. Since the inception of multidisciplinary design optimization, various methods (architectures) have been developed and applied to solve multidisciplinary design-optimization problems. This paper provides a survey of all the architectures that have been presented in the literature so far. All architectures are explained in detail using a unified description that includes optimization problem statements, diagrams, and detailed algorithms. The diagrams show both data and process flow through the multidisciplinary system and computational elements, which facilitate the understanding of the various architectures, and how they relate to each other. A classification of the multidisciplinary design-optimization architectures based on their problem formulations and decomposition strategies is also provided, and the benefits and drawbacks of the architectures are discussed from both theoretical and experimental perspectives. For each architecture, several applications to the solution of engineering-design problems are cited. The result is a comprehensive but straightforward introduction to multidisciplinary design optimization for nonspecialists and a reference detailing all current multidisciplinary design-optimization architectures for specialists. Copyright © 2013 by the authors.

@article{ibraguimova2013,
	title = {Investigation of oxygen dissociation and vibrational relaxation at temperatures 4000--10 800 {K}},
	volume = {139},
	doi = {10.1063/1.4813070},
	number = {3},
	journal = {The Journal of Chemical Physics},
	author = {Ibraguimova, L B and Sergievskaya, A L and Levashov, V Yu. and Shatalov, O P and Tunik, Yu. V and Zabelinskii, I E},
	year = {2013},
}

@inproceedings{morgenstern2013,
	title = {Full {Configuration} {Low} {Boom} {Model} and {Grids} for 2014 {Sonic} {Boom} {Prediction} {Workshop}},
	isbn = {978-1-62410-181-6},
	doi = {10.2514/6.2013-647},
	language = {en},
	urldate = {2023-01-11},
	publisher = {AIAA Paper 2013-0647},
	author = {Morgenstern, John},
	month = jan,
	year = {2013},
}

@article{bultel2013,
	title = {Elaboration of collisional–radiative models for flows related to planetary entries into the {Earth} and {Mars} atmospheres},
	volume = {22},
	url = {https://iopscience.iop.org/article/10.1088/0963-0252/22/2/025008},
	doi = {10.1088/0963-0252/22/2/025008},
	abstract = {The most relevant way to predict the excited state number density in a nonequilibrium plasma is to elaborate a collisional-radiative (CR) model taking into account most of the collisional and radiative elementary processes. Three examples of such an elaboration are given in this paper in the case of various plasma flows related to planetary atmospheric entries. The case of theoretical determination of nitrogen atom ionization or recombination global rate coefficients under electron impact is addressed first. The global rate coefficient can be implemented in multidimensional computational fluid dynamics calculations. The case of relaxation after a shock front crossing a gas of N2 molecules treated in the framework of the Rankine-Hugoniot assumptions is also studied. The vibrational and electronic specific CR model elaborated in this case allows one to understand how the plasma reaches equilibrium and to estimate the role of the radiative losses. These radiative losses play a significant role at low pressure in the third case studied. This case concerns CO2 plasma jets inductively generated in high enthalpy wind tunnels used as ground test facilities. We focus our attention on the behaviour of CO and C2 electronic excited states, the radiative signature of which can be particularly significant in this type of plasma. These three cases illustrate the elaboration of CR models and their coupling with balance equations. © 2013 IOP Publishing Ltd.},
	number = {2},
	journal = {Plasma Sources Science and Technology},
	author = {Bultel, Arnaud and Annaloro, Julien},
	month = mar,
	year = {2013},
	note = {Publisher: IOP Publishing},
}

The most relevant way to predict the excited state number density in a nonequilibrium plasma is to elaborate a collisional-radiative (CR) model taking into account most of the collisional and radiative elementary processes. Three examples of such an elaboration are given in this paper in the case of various plasma flows related to planetary atmospheric entries. The case of theoretical determination of nitrogen atom ionization or recombination global rate coefficients under electron impact is addressed first. The global rate coefficient can be implemented in multidimensional computational fluid dynamics calculations. The case of relaxation after a shock front crossing a gas of N2 molecules treated in the framework of the Rankine-Hugoniot assumptions is also studied. The vibrational and electronic specific CR model elaborated in this case allows one to understand how the plasma reaches equilibrium and to estimate the role of the radiative losses. These radiative losses play a significant role at low pressure in the third case studied. This case concerns CO2 plasma jets inductively generated in high enthalpy wind tunnels used as ground test facilities. We focus our attention on the behaviour of CO and C2 electronic excited states, the radiative signature of which can be particularly significant in this type of plasma. These three cases illustrate the elaboration of CR models and their coupling with balance equations. © 2013 IOP Publishing Ltd.

@inproceedings{chettle2013,
	title = {Edney {IV} {Interaction} {Studies} at {Mach} 5},
	author = {Chettle, Alan J and Erdem, Erinc and Kontis, Konstantinos},
	editor = {Bonazza, Riccardo and Ranjan, Devesh},
	year = {2013},
}

@inproceedings{alkandry2013,
	address = {Grapevine, TX},
	title = {Comparison of {Models} for {Mixture} {Transport} {Properties} for {Numerical} {Simulations} of {Ablative} {Heat}-{Shields}},
	doi = {10.2514/6.2013-303},
	publisher = {\{AIAA Paper\} 2013-0303},
	author = {Alkandry, Hicham and Boyd, Iain D and Martin, Alexandre},
	month = jan,
	year = {2013},
}

@book{duffa2013,
	title = {Ablative {Thermal} {Protection} {Systems} {Modeling}},
	publisher = {American Institute of Aeronautics and Astronautics, Inc.},
	author = {Duffa, Georges},
	month = may,
	year = {2013},
	doi = {10.2514/4.101717},
}

@inproceedings{eason2013,
	title = {A {Structures} {Perspective} on the {Challenges} {Associated} with {Analyzing} a {Reusable} {Hypersonic} {Platform}},
	url = {http://arc.aiaa.org},
	doi = {10.2514/6.2013-1747},
	abstract = {The AFRL Structural Sciences Center (SSC) is researching and developing methods for structural-scale simulation to address those deficiencies in the analysis of extreme-environment structures that have historically stymied the USAF and the aerospace community at large. To address these challenges, the Structural Sciences Center at the Air Force Research Laboratory, has embarked on a campaign with industry to uncover the knowledge gaps associated with defining the structural margins for a reusable Mach 5-7 air breathing class hypersonic vehicle. The current focus of this campaign includes: (1) reviewing the structural challenges encountered in past high-speed structures programs, (2) assessing the current state-of-the-art in design and analysis methods; and (3) identifying critical knowledge gaps in current methods. Each of these areas will be discussed and presented, with the goal of energizing the aerospace community to participate in helping to define and develop an appropriate series of relevant benchmark challenge problems to address key critical knowledge gaps.},
	author = {Eason, Thomas G and Spottswood, S Michael and Chona, Ravi and Penmetsa, Ravi},
	year = {2013},
}

The AFRL Structural Sciences Center (SSC) is researching and developing methods for structural-scale simulation to address those deficiencies in the analysis of extreme-environment structures that have historically stymied the USAF and the aerospace community at large. To address these challenges, the Structural Sciences Center at the Air Force Research Laboratory, has embarked on a campaign with industry to uncover the knowledge gaps associated with defining the structural margins for a reusable Mach 5-7 air breathing class hypersonic vehicle. The current focus of this campaign includes: (1) reviewing the structural challenges encountered in past high-speed structures programs, (2) assessing the current state-of-the-art in design and analysis methods; and (3) identifying critical knowledge gaps in current methods. Each of these areas will be discussed and presented, with the goal of energizing the aerospace community to participate in helping to define and develop an appropriate series of relevant benchmark challenge problems to address key critical knowledge gaps.

@article{wang2012,
	title = {Physics and {Computation} of {Aero}-{Optics}},
	volume = {44},
	doi = {10.1146/annurev-fluid-120710-101152},
	journal = {Annual Review of Fluid Mechanics},
	author = {Wang, Meng and Mani, Ali and Gordeyev, Stanislav},
	year = {2012},
	pages = {299--321},
}

@article{hosder2012,
	title = {Uncertainty and {Sensitivity} {Analysis} for {Reentry} {Flows} with {Inherent} and {Model}-{Form} {Uncertainties}},
	volume = {49},
	issn = {0022-4650, 1533-6794},
	doi = {10.2514/1.A32102},
	language = {en},
	number = {2},
	urldate = {2024-04-01},
	journal = {Journal of Spacecraft and Rockets},
	author = {Hosder, Serhat and Bettis, Benjamin R.},
	month = mar,
	year = {2012},
	pages = {193--206},
}

@article{dulikravich2012,
	title = {Inverse {Problems} in {Aerodynamics}, {Heat} {Transfer}, {Elasticity} and {Materials} {Design}},
	volume = {13},
	doi = {10.5139/IJASS.2012.13.4.405},
	number = {4},
	journal = {International Journal of Aeronautical and Space Sciences},
	author = {{George S.;Dennis, Brian H.;Baker, Daniel P.;Kennon, Stephen R.;Orlande, Helcio R.B.;Colaco, Marcelo J.; Dulikravich}},
	year = {2012},
	note = {Publisher: The Korean Society for Aeronautical and Space Sciences},
	keywords = {aerodynamic design, inverse problems, material design, thermoelasticity},
	pages = {405--420},
}

@article{patel_high_2012,
	title = {High temperature {C}/{C}–{SiC} composite by liquid silicon infiltration: a literature review},
	volume = {35},
	issn = {0973-7669},
	doi = {10.1007/s12034-011-0247-5},
	abstract = {The ceramic matrix carbon fibre (CMC) reinforced composite has received great attention for use in aerospace engineering. In aerospace, the atmosphere is highly oxidative and experiences very high temperature. In addition to this, the materials require high thermal stability and high abrasion resistance in that atmosphere. The C/C–SiC composite meets with these requirements. In this paper, the C/C–SiC composite by liquid silicon infiltration is reviewed thoroughly.},
	number = {1},
	journal = {Bulletin of Materials Science},
	author = {PATEL, MANISH and SAURABH, KUMAR and PRASAD, V. V. BHANU and SUBRAHMANYAM, J.},
	month = feb,
	year = {2012},
	pages = {63--73},
}

The ceramic matrix carbon fibre (CMC) reinforced composite has received great attention for use in aerospace engineering. In aerospace, the atmosphere is highly oxidative and experiences very high temperature. In addition to this, the materials require high thermal stability and high abrasion resistance in that atmosphere. The C/C–SiC composite meets with these requirements. In this paper, the C/C–SiC composite by liquid silicon infiltration is reviewed thoroughly.

@article{kawai2012,
	title = {Wall-modeling in large eddy simulation: {Length} scales, grid resolution, and accuracy},
	volume = {24},
	issn = {1070-6631, 1089-7666},
	shorttitle = {Wall-modeling in large eddy simulation},
	doi = {10.1063/1.3678331},
	language = {en},
	number = {1},
	urldate = {2023-01-11},
	journal = {Physics of Fluids},
	author = {Kawai, Soshi and Larsson, Johan},
	month = jan,
	year = {2012},
	pages = {015105},
}

@inproceedings{ren2012,
	address = {New Orleans, Louisiana},
	title = {Study on the {Effect} of {Compressibility} and {Knudsen} {Number} on {Aero} {Optics} in {Supersonic}/{Hypersonic} {Flows}},
	publisher = {AIAA 2012-2988},
	author = {Ren, Wei and Liu, Hong},
	month = jun,
	year = {2012},
}

@article{fidkowski2012,
	title = {Review of {Output}-{Based} {Error} {Estimation} and {Mesh} {Adaptation} in {Computational} {Fluid} {Dynamics}},
	volume = {49},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.J050073},
	doi = {10.2514/1.J050073},
	abstract = {Error estimation and control are critical ingredients for improving the reliability of computational simulations. Adjoint-based techniques can be used to both estimate the error in chosen solution outputs and to provide local indicators for adaptive refinement. This article reviews recent work on these techniques for computational fluid dynamics applications in aerospace engineering. The definition of the adjoint as the sensitivity of an output to residual source perturbations is used to derive both the adjoint equation, in fully discrete and variational formulations, and the adjoint-weighted residual method for error estimation. Assumptions and approximations made in the calculations are discussed. Presentation of the discrete and variational formulations enables a side-by-side comparison of recent work in output-error estimation using the finite volume method and the finite element method. Techniques for adapting meshes using output-error indicators are also reviewed. Recent adaptive results from a variety of laminar and Reynolds-averaged Navier-Stokes applications show the power of output-based adaptivemethods for improving the robustness of computational fluid dynamics computations. However, challenges and areas of additional future research remain, including computable error bounds and robust mesh adaptation mechanics. Copyright © 2011 by Krzysztof J. Fidkowski and David L. Darmofal. Published by the American Institute of Aeronautics and Astronautics, Inc.},
	number = {4},
	journal = {AIAA Journal},
	author = {Fidkowski, Krzysztof J. and Darmofal, David L.},
	month = apr,
	year = {2012},
	keywords = {Aerodynamic Flows, Aerodynamic Simulation, Aerospace Designs, CFD Simulation, Discontinuous Galerkin Method, Finite Volume Method, Galerkin Finite Element Method, Mesh Generation, Reynolds Averaged Navier Stokes, Sonic Booms},
	pages = {673--694},
}

Error estimation and control are critical ingredients for improving the reliability of computational simulations. Adjoint-based techniques can be used to both estimate the error in chosen solution outputs and to provide local indicators for adaptive refinement. This article reviews recent work on these techniques for computational fluid dynamics applications in aerospace engineering. The definition of the adjoint as the sensitivity of an output to residual source perturbations is used to derive both the adjoint equation, in fully discrete and variational formulations, and the adjoint-weighted residual method for error estimation. Assumptions and approximations made in the calculations are discussed. Presentation of the discrete and variational formulations enables a side-by-side comparison of recent work in output-error estimation using the finite volume method and the finite element method. Techniques for adapting meshes using output-error indicators are also reviewed. Recent adaptive results from a variety of laminar and Reynolds-averaged Navier-Stokes applications show the power of output-based adaptivemethods for improving the robustness of computational fluid dynamics computations. However, challenges and areas of additional future research remain, including computable error bounds and robust mesh adaptation mechanics. Copyright © 2011 by Krzysztof J. Fidkowski and David L. Darmofal. Published by the American Institute of Aeronautics and Astronautics, Inc.

@article{panesi2012a,
	title = {Rovibrational internal energy transfer and dissociation of {N}{\textbackslash}textsubscript\{2\}({\textbackslash}textsuperscript\{1\}\$Σ\$+g)-{N}({\textbackslash}textsuperscript\{4\}{S}{\textbackslash}textsubscript\{u\}) system in hypersonic flows},
	volume = {138},
	number = {4},
	journal = {The Journal of Chemical Physics},
	author = {Panesi, Marco and Jaffe, Richard L and Schwenke, David W and Magin, Thierry E},
	year = {2012},
	pages = {1--16},
}

@article{visbal2012,
	title = {Onset of vortex breakdown above a pitching delta wing},
	volume = {32},
	url = {https://arc.aiaa.org/doi/abs/10.2514/3.12145},
	doi = {10.2514/3.12145},
	abstract = {Computational results are presented for transient vortex breakdown above a delta wing subject to a pitch-andhold maneuver to high angle of attack. The flows are simulated by solving the full three-dimensional Navier- Stokes equations on a moving grid using the implicit Beam-Warming algorithm. An assessment of the effects of numerical resolution and favorable comparison with experimental data suggest the computational approach captures the basic dynamics of the onset and initial stages of transient breakdown. The pressure gradient along the vortex axis is found to play a dominant role in the initiation of breakdown. A description of the three-dimensional instantaneous structure of the flowfield is provided for the first time using critical-point theory. The reversed-flow region in the vortex core is associated with pairs of opposite spiral/saddle critical points. At its onset, the vortex breakdown is fairly axisymmetric; however, as it proceeds upstream and a stronger jump takes place along the axis, asymmetric effects become important and culminate in the formation of a bubble-type breakdown. This bubble structure is open and contains within itself a pair of stagnation points that are diametrically opposed and that rotate in the same sense as the upstream swirling flow. These critical points suggest the existence of azimuthal disturbances in the breakdown region. The bubble sectional topology is also found in agreement with recent experimental measurements. © 1994 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.},
	number = {8},
	journal = {AIAA Journal},
	author = {Visbal, Miguel R.},
	month = may,
	year = {2012},
	keywords = {Angle of Attack, Cambered Delta Wing, Flow Visualization Techniques, Freestream Mach Number, Navier Stokes Equations, Shear Layers, Streamlines Pattern, Taylor Vortex Flow, Velocity Profiles, Vortex Breakdown},
	pages = {1568--1575},
}

Computational results are presented for transient vortex breakdown above a delta wing subject to a pitch-andhold maneuver to high angle of attack. The flows are simulated by solving the full three-dimensional Navier- Stokes equations on a moving grid using the implicit Beam-Warming algorithm. An assessment of the effects of numerical resolution and favorable comparison with experimental data suggest the computational approach captures the basic dynamics of the onset and initial stages of transient breakdown. The pressure gradient along the vortex axis is found to play a dominant role in the initiation of breakdown. A description of the three-dimensional instantaneous structure of the flowfield is provided for the first time using critical-point theory. The reversed-flow region in the vortex core is associated with pairs of opposite spiral/saddle critical points. At its onset, the vortex breakdown is fairly axisymmetric; however, as it proceeds upstream and a stronger jump takes place along the axis, asymmetric effects become important and culminate in the formation of a bubble-type breakdown. This bubble structure is open and contains within itself a pair of stagnation points that are diametrically opposed and that rotate in the same sense as the upstream swirling flow. These critical points suggest the existence of azimuthal disturbances in the breakdown region. The bubble sectional topology is also found in agreement with recent experimental measurements. © 1994 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

@article{nicholson2012,
	title = {On finite element analysis of an inverse problem in elasticity},
	volume = {20},
	doi = {10.1080/17415977.2012.668677},
	abstract = {This investigation concerns an inverse problem modelled by the finite element method. For a given mesh and set of physical properties, even though a well-posed direct problem possesses a unique sol...},
	number = {5},
	journal = {Inverse Problems in Science and Engineering},
	author = {Nicholson, David W.},
	month = sep,
	year = {2012},
	note = {Publisher: Taylor \& Francis},
	keywords = {finite element modelling, inverse modelling, matrix nonsingularity condition, mesh modification},
	pages = {735--748},
}

This investigation concerns an inverse problem modelled by the finite element method. For a given mesh and set of physical properties, even though a well-posed direct problem possesses a unique sol...

@article{bisek2012,
	title = {Numerical {Study} of {Plasma}-{Assisted} {Aerodynamic} {Control} for {Hypersonic} {Vehicles}},
	volume = {46},
	doi = {10.2514/1.39032},
	abstract = {Plasma actuators and various forms of volumetric energy deposition have received a good deal of research attention recently as a means of hypersonic flight control. An open question remains as to whether the required power expenditures for such devices can be achieved for practical systems. To address this issue, a numerical study is carried out for hypersonic flow over a blunt-nose elliptic cone to determine the amount of energy deposition necessary for flight control. Energy deposition is simulated by means of a phenomenological dissipative heating model. A parametric study of the effects of energy deposition is carried outfor several blunt elliptic cone configurations. Three different volumetric energy deposition patterns are considered: a spherical pattern, a "pancake" pattern (oblate spheroid), and a "bean" pattern (prolate spheroid). The effectiveness of volumetric energy deposition for flight control appears to scale strongly with a nondimensional parameter based on the freestream flow kinetic energy flux. Copyright Clearance Center Inc.,.},
	number = {3},
	journal = {Journal of Spacecraft and Rockets},
	author = {Bisek, Nicholas J. and Boyd, Iain D. and Poggie, Jonathan},
	month = may,
	year = {2012},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Bow Shock, Flight Control, Freestream Conditions, Hypersonic Flows, Hypersonic Vehicles, Pressure Coefficient, Thermal Nonequilibrium, Thermal Protection System, Vibrational Energy, Wall Temperature},
	pages = {568--576},
}

Plasma actuators and various forms of volumetric energy deposition have received a good deal of research attention recently as a means of hypersonic flight control. An open question remains as to whether the required power expenditures for such devices can be achieved for practical systems. To address this issue, a numerical study is carried out for hypersonic flow over a blunt-nose elliptic cone to determine the amount of energy deposition necessary for flight control. Energy deposition is simulated by means of a phenomenological dissipative heating model. A parametric study of the effects of energy deposition is carried outfor several blunt elliptic cone configurations. Three different volumetric energy deposition patterns are considered: a spherical pattern, a "pancake" pattern (oblate spheroid), and a "bean" pattern (prolate spheroid). The effectiveness of volumetric energy deposition for flight control appears to scale strongly with a nondimensional parameter based on the freestream flow kinetic energy flux. Copyright Clearance Center Inc.,.

@article{hou2012,
	title = {Numerical {Methods} for {Fluid}-{Structure} {Interaction} — {A} {Review}},
	volume = {12},
	url = {https://www.cambridge.org/core/journals/communications-in-computational-physics/article/numerical-methods-for-fluidstructure-interaction-a-review/359AE654882EAFB08CAAA862AC7B05AC},
	doi = {10.4208/CICP.291210.290411S},
	abstract = {The interactions between incompressible fluid flows and immersed structures are nonlinear multi-physics phenomena that have applications to a wide range of scientific and engineering disciplines. In this article, we review representative numerical methods based on conforming and non-conforming meshes that are currently available for computing fluid-structure interaction problems, with an emphasis on some of the recent developments in the field. A goal is to categorize the selected methods and assess their accuracy and efficiency. We discuss challenges faced by researchers in this field, and we emphasize the importance of interdisciplinary effort for advancing the study in fluid-structure interactions.},
	number = {2},
	journal = {Communications in Computational Physics},
	author = {Hou, Gene and Wang, Jin and Layton, Anita},
	month = aug,
	year = {2012},
	note = {Publisher: Cambridge University Press},
	keywords = {65-02, 65Z05, 74F10, Fluid-structure interaction, conforming and non-conforming meshes, immersed methods},
	pages = {337--377},
}

The interactions between incompressible fluid flows and immersed structures are nonlinear multi-physics phenomena that have applications to a wide range of scientific and engineering disciplines. In this article, we review representative numerical methods based on conforming and non-conforming meshes that are currently available for computing fluid-structure interaction problems, with an emphasis on some of the recent developments in the field. A goal is to categorize the selected methods and assess their accuracy and efficiency. We discuss challenges faced by researchers in this field, and we emphasize the importance of interdisciplinary effort for advancing the study in fluid-structure interactions.

@inproceedings{allmaras2012,
	title = {Modications and {Clarications} for the {Implementation} of the {Spalart}-{Allmaras} {Turbulence} {Model}},
	abstract = {We present modications to the Spalart-Allmaras (S-A) turbulence model targeted toward situations of under-resolved grids and unphysical transient states. These modications are formulated to be passive to the original model in well resolved owelds and should produce negligible dierences in most cases. They are motivated primarily by numerical issues near the interface between turbulent and irrotational regions. We also comment on the appropriate form of S-A for compressible ows, the inclusion of the laminar suppression term for fully turbulent ows, and the use of maximum value limiters on the turbulence solution. We also present a new analytic solution to S-A for law of the wall velocity.},
	publisher = {Seventh International Conference on Computational Fluid Dynamics},
	author = {Allmaras, Steven R and Johnson, Forrester T and Spalart, Philippe R},
	year = {2012},
	keywords = {Computational Fluid Dynamics, Turbulence Modeling},
	pages = {9--13},
}

We present modications to the Spalart-Allmaras (S-A) turbulence model targeted toward situations of under-resolved grids and unphysical transient states. These modications are formulated to be passive to the original model in well resolved owelds and should produce negligible dierences in most cases. They are motivated primarily by numerical issues near the interface between turbulent and irrotational regions. We also comment on the appropriate form of S-A for compressible ows, the inclusion of the laminar suppression term for fully turbulent ows, and the use of maximum value limiters on the turbulence solution. We also present a new analytic solution to S-A for law of the wall velocity.

@article{alonso2012,
	title = {Multidisciplinary {Optimization} with {Applications} to {Sonic}-{Boom} {Minimization}},
	volume = {44},
	url = {http://www.annualreviews.org/doi/10.1146/annurev-fluid-120710-101133},
	doi = {10.1146/annurev-fluid-120710-101133},
	abstract = {This article presents a review of key historical contributions, the current status, and future research avenues in support of the development of supersonic aircraft that are sufficiently quiet so that they can be allowed to fly supersonically over land. For this goal to be achievable, in addition to overcoming many other challenges in aerodynamics, structures, propulsion, acoustics, and aeroservoelasticity, the pressure signature created by the aircraft must be such that, when it reaches the ground, (a) it can barely be perceived by the human ear, and (b) it results in disturbances to man-made structures that do not exceed the threshold of annoyance for a significant percentage of the population. In other words, the ground-boom signature must meet a number of key constraints that can be appropriately quantified. In designing aircraft with low sonic booms, it is important to understand (a) how pressure disturbances are generated and how they propagate through the atmosphere, (b) under which conditions will the pressure signature created by an aircraft evolve to generate an acceptable low-boom signature at the ground, and (c) what multidisciplinary trade-offs need to be made to realize low-boom aircraft that are also economically and environmentally compliant. This article discusses each of these areas separately, assesses the accomplishments in each topic, identifies significant shortcomings, and suggests future research efforts (some already ongoing) that have the potential to yield solutions to all these issues.},
	number = {1},
	journal = {Annual Review of Fluid Mechanics},
	author = {Alonso, Juan J. and Colonno, Michael R.},
	month = jan,
	year = {2012},
	note = {Publisher: Annual Reviews},
	keywords = {Aircraft design, Boom propagation, Noise, Perceived loudness, Robust design, Supersonic design, Supersonic flow},
	pages = {505--526},
}

This article presents a review of key historical contributions, the current status, and future research avenues in support of the development of supersonic aircraft that are sufficiently quiet so that they can be allowed to fly supersonically over land. For this goal to be achievable, in addition to overcoming many other challenges in aerodynamics, structures, propulsion, acoustics, and aeroservoelasticity, the pressure signature created by the aircraft must be such that, when it reaches the ground, (a) it can barely be perceived by the human ear, and (b) it results in disturbances to man-made structures that do not exceed the threshold of annoyance for a significant percentage of the population. In other words, the ground-boom signature must meet a number of key constraints that can be appropriately quantified. In designing aircraft with low sonic booms, it is important to understand (a) how pressure disturbances are generated and how they propagate through the atmosphere, (b) under which conditions will the pressure signature created by an aircraft evolve to generate an acceptable low-boom signature at the ground, and (c) what multidisciplinary trade-offs need to be made to realize low-boom aircraft that are also economically and environmentally compliant. This article discusses each of these areas separately, assesses the accomplishments in each topic, identifies significant shortcomings, and suggests future research efforts (some already ongoing) that have the potential to yield solutions to all these issues.

@article{kim2012,
	title = {Modeling of {Electron} {Energy} {Phenomena} in {Hypersonic} {Flows}},
	volume = {26},
	issn = {08878722/12},
	doi = {10.2514/1.T3716},
	abstract = {Studies are described for modeling electron energy phenomena for hypersonic flows. The electron energy must be modeled separately from other energy modes because it may have a significant effect on vibrational relaxation and chemical reactions. Whenever flows are in a strong thermal nonequilibrium state, an electron energy equation should be considered. In the considered electron energy equation, the electron energy relaxations of each energy mode are accounted for, which include translational-electron, rotational-electron, and vibrational-electron energy relaxation. To avoid a singularity of the Jacobian in the electron energy equation, we introduce a modified electron energy expression. The suggested electron-energy model is implemented into a hypersonic flow code for both explicit and implicit methods. In the present study, we numerically simulate the electron energy with electron-vibrational relaxation for diatomic nitrogen. For the assessment of the electron-energy model, we simulate several cases, which are a plasma wind-tunnel, a radio attenuation measurement (RAM)-C case, the entry of the automated transfer vehicle, and the Stardust reentry capsule. Nomenclature b 0 = scattering parameter for 90 deg, Ze 2 †=12" 0 kT e †, m 2 C V;e = electron specific heat capacity, 3=2† R=M e †, J=kg K† c s = species charge D s = species diffusion coefficients, m 2 =s E e = electron energy, e ‰C v;e T e ‡ 1=2†u 2 ‡ v 2 ‡ w 2 †Š E i;f = first ionization energy per unit mass, J=kg E rot = rotational energy E vib = vibrational energy e = elementary charge, 1:6022 10 19 C e e = electron energy per unit mass of electrons, C V;e T e ‡ 1=2†u 2 ‡ v 2 ‡ w 2 † e e = modified electron energy per unit mass, e =†e e e vib;s = vibrational energy per unit mass F = inviscid flux vector H = total enthalpy per unit mass, J=kg J e = electron diffusion flux k = Boltzmann constant, 1:38065 10 23 ‰m 2 kg s 2 K 1 Š k ev 0;j = vibrational-excitation rate coefficient from vibrational state 0 to j, m 3 =s M s = molecular weight of species s m s = species mass, kg n = unit vector normal to computational cell face n e = electron number density, m 3 p e = electron pressure, Pa Q = vector of conserved variables q e = electron heat flux R = universal gas constant, 8314.3, J=kg mole K S chem;e = electron energy gained by the electrons generated from chemical reactions S e = source term S e;modified = modified source term of the electron energy equation that includes the electron pressure term S epg = approximation of the work done on electrons by the electric field induced by the electron pressure gradient S inelastic;e = rate of inelastic energy exchange between electrons and molecules S transe = energy exchange between translational and electron energies T e = electron temperature, K T trans = translational temperature, K T tr = translational-rotational temperature, K T ve = vibrational-electron-electronic temperature, K U = velocity component normal to computational cell face u = flow velocity Y s = species mass fraction v;s = species characteristic vibrational temperature = thermal conductivity, K W=m† D = Debye length, m = viscosity coefficient, N s†=m s = species density, kg=m 3 es = collision cross section for electron and s species, m 2 e = electron viscous stress es = electron-vibrational relaxation time, s \_ ! e = electron-mass production rate by chemical reactions, kg=m 3 s " 0 = vacuum permittivity, 8:854 10 12 , C V 1 m 1},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Kim, Minkwan and Gülhan, Ali and Boyd, Iain D},
	year = {2012},
}

Studies are described for modeling electron energy phenomena for hypersonic flows. The electron energy must be modeled separately from other energy modes because it may have a significant effect on vibrational relaxation and chemical reactions. Whenever flows are in a strong thermal nonequilibrium state, an electron energy equation should be considered. In the considered electron energy equation, the electron energy relaxations of each energy mode are accounted for, which include translational-electron, rotational-electron, and vibrational-electron energy relaxation. To avoid a singularity of the Jacobian in the electron energy equation, we introduce a modified electron energy expression. The suggested electron-energy model is implemented into a hypersonic flow code for both explicit and implicit methods. In the present study, we numerically simulate the electron energy with electron-vibrational relaxation for diatomic nitrogen. For the assessment of the electron-energy model, we simulate several cases, which are a plasma wind-tunnel, a radio attenuation measurement (RAM)-C case, the entry of the automated transfer vehicle, and the Stardust reentry capsule. Nomenclature b 0 = scattering parameter for 90 deg, Ze 2 †=12" 0 kT e †, m 2 C V;e = electron specific heat capacity, 3=2† R=M e †, J=kg K† c s = species charge D s = species diffusion coefficients, m 2 =s E e = electron energy, e ‰C v;e T e ‡ 1=2†u 2 ‡ v 2 ‡ w 2 †Š E i;f = first ionization energy per unit mass, J=kg E rot = rotational energy E vib = vibrational energy e = elementary charge, 1:6022 10 19 C e e = electron energy per unit mass of electrons, C V;e T e ‡ 1=2†u 2 ‡ v 2 ‡ w 2 † e e = modified electron energy per unit mass, e =†e e e vib;s = vibrational energy per unit mass F = inviscid flux vector H = total enthalpy per unit mass, J=kg J e = electron diffusion flux k = Boltzmann constant, 1:38065 10 23 ‰m 2 kg s 2 K 1 Š k ev 0;j = vibrational-excitation rate coefficient from vibrational state 0 to j, m 3 =s M s = molecular weight of species s m s = species mass, kg n = unit vector normal to computational cell face n e = electron number density, m 3 p e = electron pressure, Pa Q = vector of conserved variables q e = electron heat flux R = universal gas constant, 8314.3, J=kg mole K S chem;e = electron energy gained by the electrons generated from chemical reactions S e = source term S e;modified = modified source term of the electron energy equation that includes the electron pressure term S epg = approximation of the work done on electrons by the electric field induced by the electron pressure gradient S inelastic;e = rate of inelastic energy exchange between electrons and molecules S transe = energy exchange between translational and electron energies T e = electron temperature, K T trans = translational temperature, K T tr = translational-rotational temperature, K T ve = vibrational-electron-electronic temperature, K U = velocity component normal to computational cell face u = flow velocity Y s = species mass fraction v;s = species characteristic vibrational temperature = thermal conductivity, K W=m† D = Debye length, m = viscosity coefficient, N s†=m s = species density, kg=m 3 es = collision cross section for electron and s species, m 2 e = electron viscous stress es = electron-vibrational relaxation time, s _ ! e = electron-mass production rate by chemical reactions, kg=m 3 s " 0 = vacuum permittivity, 8:854 10 12 , C V 1 m 1

@book{townes2012,
	title = {Microwave {Spectroscopy}},
	publisher = {Dover Publications, Inc.},
	author = {Townes, C H and Schawlow, A L},
	year = {2012},
}

@article{das2012a,
	title = {Inverse analysis of {Navier}–{Stokes} equations using simplex search method},
	volume = {20},
	doi = {10.1080/17415977.2011.629046},
	abstract = {The 2-D Navier–Stokes (N–S) equation is solved for the simultaneous estimation of three parameters such as the Reynold's number (Re), the length of the enclosure (lx) and the width of the enclosure...},
	number = {4},
	journal = {Inverse Problems in Science and Engineering},
	author = {Das, Ranjan},
	month = jun,
	year = {2012},
	note = {Publisher: Taylor \& Francis},
	keywords = {Navier–Stokes equation, Reynold's number, inverse problem, length, parameter estimation, simplex search method, width},
	pages = {445--462},
}

The 2-D Navier–Stokes (N–S) equation is solved for the simultaneous estimation of three parameters such as the Reynold's number (Re), the length of the enclosure (lx) and the width of the enclosure...

@article{yu2012,
	title = {High resolution spectral analysis of oxygen. {I}. {Isotopically} invariant {Dunham} fit for the {X3Σg}−, {a1Δg}, {b1Σg}+ states},
	volume = {137},
	url = {https://doi.org/10.1063/1.4719170},
	doi = {10.1063/1.4719170},
	number = {2},
	journal = {The Journal of Chemical Physics},
	author = {Yu, Shanshan and Miller, Charles E and Drouin, Brian J and Müller, Holger S P},
	year = {2012},
	pages = {24304--24304},
}

@article{martin2012,
	title = {High performance modeling of atmospheric re-entry vehicles},
	volume = {341},
	journal = {Journal of Physics: Conference Series},
	author = {Martin, Alexandre and Scalabrin, Leonardo C and Boyd, Iain D},
	year = {2012},
	pages = {1--12},
}

@article{barbante2012,
	title = {Flight {Extrapolation} of {Plasma} {Wind} {Tunnel} {Stagnation} {Region} {Flowfield}},
	volume = {20},
	url = {https://arc.aiaa.org/doi/10.2514/1.17185},
	doi = {10.2514/1.17185},
	abstract = {Development of reusable space vehicles requires a precise qualification of their thermal protection system materials. The catalytic properties are usually determined in plasma wind tunnels for test conditions relevant to the flight mission program. Therefore, for such a situation, it is important to have a methodology that allows the correct extrapolation of the ground test conditions to the real flight ones and vice-versa. The local heat transfer simulation concept presented in this paper is a possible strategy for accomplishing this task. Computational results show that the ground test conditions are indeed correctly extrapolated to the flight ones and a simple method of accounting for possible discrepancies between the two configurations is presented.},
	number = {3},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Barbante, P. F. and Chazot, O.},
	month = may,
	year = {2012},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Accurate Computational Fluid Dynamics, Binary Diffusion Coefficient, Boundary Layer Equations, Damköhler Numbers, Freestream Conditions, Heat Transfer, Hypersonic Flows, Shock Layers, Thermal Protection System, Wind Tunnels},
	pages = {493--499},
}

Development of reusable space vehicles requires a precise qualification of their thermal protection system materials. The catalytic properties are usually determined in plasma wind tunnels for test conditions relevant to the flight mission program. Therefore, for such a situation, it is important to have a methodology that allows the correct extrapolation of the ground test conditions to the real flight ones and vice-versa. The local heat transfer simulation concept presented in this paper is a possible strategy for accomplishing this task. Computational results show that the ground test conditions are indeed correctly extrapolated to the flight ones and a simple method of accounting for possible discrepancies between the two configurations is presented.

@article{panesi2012,
	title = {Fire {II} {Flight} {Experiment} {Analysis} by {Means} of a {Collisional}-{Radiative} {Model}},
	volume = {23},
	url = {https://arc.aiaa.org/doi/abs/10.2514/1.39034},
	doi = {10.2514/1.39034},
	abstract = {We study the behavior of the excited electronic states of atoms in the relaxation zone of one-dimensional airflows obtained in shock-tube facilities. A collisional-radiative model is developed, accounting for thermal nonequilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The electronic states of atoms are treated as separate species, allowing for non-Boltzmann distributions of their populations. Relaxation of the free-electron energy is also accounted for by using a separate conservation equation. We apply the model to three trajectory points of the Fire II flight experiment. In the rapidly ionizing regime behind strong shock waves, the electronic energy level populations depart from Boltzmann distributions because the highlying bound electronic states are depleted. To quantify the extent of this nonequilibrium effect, we compare the results obtained by means of the collisional-radiative model with those based on Boltzmann distributions. For the earliest trajectory point, we show that the quasi-steady-state assumption is only valid for the high-lying excited states and cannot be extended to the metastable states. © 2008 by the American Institute of Aeronautics and Astronautics, Inc.},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Panesi, Marco and Magin, Thierry and Bourdon, Anne and Bultel, Arnaud and Chazot, O.},
	month = may,
	year = {2012},
	note = {Publisher: American Institute of Aeronautics and Astronautics Inc.},
	keywords = {Degree of Ionization, Energy Distribution, Flow Characteristics, Freestream, One Dimensional Flow, Quasi Steady States, Rankine Hugoniot Relation, Shock Layers, Spontaneous Emission, Thermal Nonequilibrium},
	pages = {236--248},
}

We study the behavior of the excited electronic states of atoms in the relaxation zone of one-dimensional airflows obtained in shock-tube facilities. A collisional-radiative model is developed, accounting for thermal nonequilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The electronic states of atoms are treated as separate species, allowing for non-Boltzmann distributions of their populations. Relaxation of the free-electron energy is also accounted for by using a separate conservation equation. We apply the model to three trajectory points of the Fire II flight experiment. In the rapidly ionizing regime behind strong shock waves, the electronic energy level populations depart from Boltzmann distributions because the highlying bound electronic states are depleted. To quantify the extent of this nonequilibrium effect, we compare the results obtained by means of the collisional-radiative model with those based on Boltzmann distributions. For the earliest trajectory point, we show that the quasi-steady-state assumption is only valid for the high-lying excited states and cannot be extended to the metastable states. © 2008 by the American Institute of Aeronautics and Astronautics, Inc.

@inproceedings{stern2012,
	title = {Estimation of dynamic stability coefficients for aerodynamic decelerators using {CFD}},
	isbn = {978-1-62410-185-4},
	url = {https://arc.aiaa.org/doi/10.2514/6.2012-3225},
	doi = {10.2514/6.2012-3225},
	abstract = {A method for performing dynamic simulations of entry vehicles is developed. This capability uses existing infrastructure within the US3D flow solver, developed for doing fluid structure interaction (FSI) simulations, to allow for up to six degree of freedom (6- DoF) simulations. Inviscid, free-to-oscillate simulations of the Mars Science Laboratory (MSL) capsule at Mach 2.5 and 3.5 are used to evaluate different data reduction methods. It is found that many simulations may be required to get reliable data. The computed pitch damping coefficients show comparable trends to ballistic range data, though they differ in magnitude, particularly at high angles of attack. Preliminary viscous simulation results are presented, and show improved agreement with experimental data compared to the inviscid analysis. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.},
	publisher = {AIAA Paper 2012-3225},
	author = {Stern, Eric C. and Gidzak, Vladimyr M. and Candler, Graham V.},
	year = {2012},
	pages = {2217--2230},
}

A method for performing dynamic simulations of entry vehicles is developed. This capability uses existing infrastructure within the US3D flow solver, developed for doing fluid structure interaction (FSI) simulations, to allow for up to six degree of freedom (6- DoF) simulations. Inviscid, free-to-oscillate simulations of the Mars Science Laboratory (MSL) capsule at Mach 2.5 and 3.5 are used to evaluate different data reduction methods. It is found that many simulations may be required to get reliable data. The computed pitch damping coefficients show comparable trends to ballistic range data, though they differ in magnitude, particularly at high angles of attack. Preliminary viscous simulation results are presented, and show improved agreement with experimental data compared to the inviscid analysis. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

@techreport{adler2012,
	title = {Entry, {Decent}, and {Landing} {Roadmap}: {Technology} {Area} 9},
	author = {Adler, Mark and Wright, Michael and Campbell, Charles and Clark, Ian and Engelund, Walt and Rivellini, Tommaso},
	year = {2012},
}

@inproceedings{ibraguimova2012,
	title = {Equilibrium and non-equilibrium rate constants of oxygen dissociation at high temperatures},
	volume = {1501},
	author = {Ibraguimova, L B and Shatalov, O P and Tunik, Y V},
	year = {2012},
	note = {Issue: 1},
	pages = {1094--1101},
}

@article{das2012,
	title = {A simulated annealing-based inverse computational fluid dynamics model for unknown parameter estimation in fluid flow problem},
	volume = {26},
	url = {https://www.tandfonline.com/doi/abs/10.1080/10618562.2011.632375},
	doi = {10.1080/10618562.2011.632375},
	abstract = {In this paper, a simulated annealing (SA)-based optimisation is carried out for simultaneous estimation of the Reynolds number (Re) and the dimensions of the enclosure (lx, ly ) from the knowledge ...},
	number = {9-10},
	journal = {International Journal of Computational Fluid Dynamics},
	author = {Das, Ranjan},
	month = oct,
	year = {2012},
	note = {Publisher: Taylor \& Francis},
	keywords = {inverse problem, lid-driven cavity flow, simulated annealing, width},
	pages = {499--513},
}

In this paper, a simulated annealing (SA)-based optimisation is carried out for simultaneous estimation of the Reynolds number (Re) and the dimensions of the enclosure (lx, ly ) from the knowledge ...

@book{Feynman2011a,
	edition = {Millennium},
	title = {The feynman lectures on physics, volume {II}},
	isbn = {978-0-465-07998-8},
	publisher = {Basic Books},
	author = {Feynman, Richard P. and Leinghton B., Robert and Matthew, Sands},
	year = {2011},
}

@book{Feynman2011b,
	edition = {Millennium},
	title = {The feynman lectures on physics, volume {III}},
	isbn = {978-0-465-02417-9},
	publisher = {Basic Books},
	author = {Feynman, Richard P. and Leighton B., Robert and Matthew, Sands},
	year = {2011},
}

@book{Feynman2011,
	edition = {Millennium},
	title = {The feynman lectures on physics, volume {I}},
	isbn = {978-0-465-02414-8},
	publisher = {Basic Books},
	author = {Feynman, Richard P. and Leighton B., Robert and Matthew, Sands},
	year = {2011},
}

@article{fruchtman2011,
	title = {Potential of an emissive cylindrical probe in plasma},
	volume = {84},
	url = {https://link.aps.org/doi/10.1103/PhysRevE.84.025402},
	doi = {10.1103/PhysRevE.84.025402},
	abstract = {The floating potential of an emissive cylindrical probe in a plasma is calculated for an arbitrary ratio of Debye length to probe radius and for an arbitrary ion composition. In their motion to the probe the ions are assumed to be collisionless. For a small Debye length, a two-scale analysis for the quasineutral plasma and for the sheath provides analytical expressions for the emitted and collected currents and for the potential as functions of a generalized mass ratio. For a Debye length that is not small, it is demonstrated that, as the Debye length becomes larger, the probe potential approaches the plasma potential and that the ion density near the probe is not smaller but rather is larger than it is in the plasma bulk.},
	number = {2},
	urldate = {2024-04-23},
	journal = {Physical Review E},
	author = {Fruchtman, A. and Zoler, D. and Makrinich, G.},
	month = aug,
	year = {2011},
	pages = {025402},
}

The floating potential of an emissive cylindrical probe in a plasma is calculated for an arbitrary ratio of Debye length to probe radius and for an arbitrary ion composition. In their motion to the probe the ions are assumed to be collisionless. For a small Debye length, a two-scale analysis for the quasineutral plasma and for the sheath provides analytical expressions for the emitted and collected currents and for the potential as functions of a generalized mass ratio. For a Debye length that is not small, it is demonstrated that, as the Debye length becomes larger, the probe potential approaches the plasma potential and that the ion density near the probe is not smaller but rather is larger than it is in the plasma bulk.

@article{jacobson_active_2011,
	title = {Active {Oxidation} of {SiC}},
	volume = {75},
	issn = {1573-4889},
	doi = {10.1007/s11085-010-9216-4},
	abstract = {Silicon carbide (SiC) forms a protective condensed-phase oxide (SiO2) in passive oxidation and a volatile sub-oxide (SiO(g)) in active oxidation. The transition between these two modes of oxidation and the rates of active oxidation are critical issues. A literature review indicates that impurity effects, the difference between active-to-passive and passive-to-active transitions, and the effect of total pressure on these transitions remain unexplored for SiC. Measurements were made in a thermogravimetric apparatus (TGA) by changing oxygen potentials either by blending O2/Ar mixtures or changing total pressures in a pure oxygen gas stream to the point where a transition occurs. Specimens were examined with standard optical and electron-optical techniques. Active-to-passive and passive-to-active transitions were measured and found to be similar for SiC, which is in contrast to pure Si. The similarity in SiC is attributed to SiC/SiO2 interfacial reactions producing the necessary conditions for passive scale formation (active-to-passive) or passive scale breakdown (passive-to-active). Comparable results were obtained in both the O2/Ar and reduced total O2 pressure cases for SiC.},
	language = {en},
	number = {1},
	urldate = {2023-10-26},
	journal = {Oxidation of Metals},
	author = {Jacobson, N. S. and Myers, D. L.},
	month = feb,
	year = {2011},
	keywords = {Active oxidation, Ceramics, Silicon carbide},
	pages = {1--25},
}

Silicon carbide (SiC) forms a protective condensed-phase oxide (SiO2) in passive oxidation and a volatile sub-oxide (SiO(g)) in active oxidation. The transition between these two modes of oxidation and the rates of active oxidation are critical issues. A literature review indicates that impurity effects, the difference between active-to-passive and passive-to-active transitions, and the effect of total pressure on these transitions remain unexplored for SiC. Measurements were made in a thermogravimetric apparatus (TGA) by changing oxygen potentials either by blending O2/Ar mixtures or changing total pressures in a pure oxygen gas stream to the point where a transition occurs. Specimens were examined with standard optical and electron-optical techniques. Active-to-passive and passive-to-active transitions were measured and found to be similar for SiC, which is in contrast to pure Si. The similarity in SiC is attributed to SiC/SiO2 interfacial reactions producing the necessary conditions for passive scale formation (active-to-passive) or passive scale breakdown (passive-to-active). Comparable results were obtained in both the O2/Ar and reduced total O2 pressure cases for SiC.

@book{babinsky2011,
	title = {Shock wave-boundary-layer interactions},
	publisher = {Cambridge University Press},
	author = {Babinsky, Holger and Harvey, John},
	year = {2011},
}

@phdthesis{stemmer2011,
	title = {Investigations on the instability of hypersonic boundary layers, taking into account high-temperature effects},
	school = {Technical University of Munich},
	author = {Stemmer, C},
	year = {2011},
}

@article{culler2011,
	title = {Impact of {Fluid}-{Thermal}-{Structural} {Coupling} on {Response} {Prediction} of {Hypersonic} {Skin} {Panels}},
	volume = {49},
	issn = {0001-1452},
	doi = {10.2514/1.J050617},
	number = {11},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {Culler, Adam J. and McNamara, Jack J.},
	year = {2011},
	pages = {2393--2406},
}

@article{mcnamara2011,
	title = {Aeroelastic and {Aerothermoelastic} {Analysis} in {Hypersonic} {Flow}: {Past}, {Present}, and {Future}},
	volume = {49},
	issn = {0001-1452},
	shorttitle = {Aeroelastic and {Aerothermoelastic} {Analysis} in {Hypersonic} {Flow}},
	doi = {10.2514/1.J050882},
	number = {6},
	urldate = {2023-08-03},
	journal = {AIAA Journal},
	author = {McNamara, Jack J. and Friedmann, Peretz P.},
	month = jun,
	year = {2011},
	keywords = {Aerodynamic Center, Aeroelastic Stability, Arbitrary Lagrangian Eulerian, CFD Analysis, Hypersonic Aerothermodynamics, Hypersonic Vehicles, Inviscid Hypersonic Flow, Orbital Sciences Corporation, Turbomachinery, Wind Turbine Aerodynamics},
	pages = {1089--1122},
}

@inproceedings{gnoffo2011,
	title = {Uncertainty {Assessments} of {2D} and {Axisymmetric} {Hypersonic} {Shock} {Wave}-{Turbulent} {Boundary} {Layer} {Interaction} {Simulations} at {Compression} {Corners}},
	doi = {10.2514/6.2011-3142},
	abstract = {This paper is one of a series of five papers in a special session organized by the NASA Fundamental Aeronautics Program that addresses uncertainty assessments for CFD simulations in hypersonic flow. Simulations of a shock emanating from a compression corner and interacting with a fully developed turbulent boundary layer are evaluated herein. Mission relevant conditions at Mach 7 and Mach 14 are defined for a pre-compression ramp of a scramjet powered vehicle. Three compression angles are defined-the smallest to avoid separation losses and the largest to force a separated flow engaging more complicated flow physics. The Baldwin-Lomax and the Cebeci-Smith algebraic models, the one-equation Spalart-Allmaras model with the Catrix-Aupoix compressibility modification and two-equation models including Menter SST, Wilcox k − ω 98, and Wilcox k − ω 06 turbulence models are evaluated. Each model is fully defined herein to preclude any ambiguity regarding model implementation. Comparisons are made to existing experimental data and Van Driest theory to provide preliminary assessment of model form uncertainty. A set of coarse grained uncertainty metrics are defined to capture essential differences among turbulence models. Except for the inability of algebraic models to converge for some separated flows there is no clearly superior model as judged by these metrics. A preliminary metric for the numerical component of uncertainty in shock-turbulent-boundary-layer interactions at compression corners sufficiently steep to cause separation is defined as 55\%. This value is a median of differences with experimental data averaged for peak pressure and heating and for extent of separation captured in new, grid-converged solutions presented here. This value is consistent with existing results in a literature review of hypersonic shock-turbulent-boundary-layer interactions by Roy and Blottner and with more recent computations of MacLean.},
	author = {Gnoffo, Peter A and Berry, Scott A and Van Norman, John W},
	year = {2011},
}

This paper is one of a series of five papers in a special session organized by the NASA Fundamental Aeronautics Program that addresses uncertainty assessments for CFD simulations in hypersonic flow. Simulations of a shock emanating from a compression corner and interacting with a fully developed turbulent boundary layer are evaluated herein. Mission relevant conditions at Mach 7 and Mach 14 are defined for a pre-compression ramp of a scramjet powered vehicle. Three compression angles are defined-the smallest to avoid separation losses and the largest to force a separated flow engaging more complicated flow physics. The Baldwin-Lomax and the Cebeci-Smith algebraic models, the one-equation Spalart-Allmaras model with the Catrix-Aupoix compressibility modification and two-equation models including Menter SST, Wilcox k − ω 98, and Wilcox k − ω 06 turbulence models are evaluated. Each model is fully defined herein to preclude any ambiguity regarding model implementation. Comparisons are made to existing experimental data and Van Driest theory to provide preliminary assessment of model form uncertainty. A set of coarse grained uncertainty metrics are defined to capture essential differences among turbulence models. Except for the inability of algebraic models to converge for some separated flows there is no clearly superior model as judged by these metrics. A preliminary metric for the numerical component of uncertainty in shock-turbulent-boundary-layer interactions at compression corners sufficiently steep to cause separation is defined as 55%. This value is a median of differences with experimental data averaged for peak pressure and heating and for extent of separation captured in new, grid-converged solutions presented here. This value is consistent with existing results in a literature review of hypersonic shock-turbulent-boundary-layer interactions by Roy and Blottner and with more recent computations of MacLean.

@inproceedings{bowcutt2011,
	address = {San Francisco, CA},
	title = {The {Hypersonic} {Space} and {Global} {Transportation} {System}: {A} {Concept} for {Routine} and {Affordable} {Access} to {Space}},
	publisher = {\{AIAA Paper\} 2011-2295},
	author = {Bowcutt, Kevin G and Smith, Thomas R and Kothari, Ajay P and Raghavan, Venkataraman and Tarpley, Christopher and Livingston, John W},
	year = {2011},
}

@article{kim2011,
	title = {Solvated {Electrons} in {High}-{Temperature} {Melts} and {Glasses} of the {Room}-{Temperature} {Stable} {Electride} [\{{Ca}\}{\textbackslash}textsubscript\{24\}\{{Al}\}{\textbackslash}textsubscript\{28\}\{{O}\}{\textbackslash}textsubscript\{64\}]{\textbackslash}textsuperscript\{4+\} 4 e{\textbackslash}textsuperscript\{-\}},
	volume = {333},
	number = {6038},
	journal = {Science},
	author = {Kim, S W and Shimoyama, T and Hosono, H},
	year = {2011},
	pages = {71--74},
}

@inproceedings{bruceowens2011,
	title = {Overview of orion crew module and launch abort vehicle dynamic stability},
	isbn = {978-1-62410-145-8},
	url = {https://arc.aiaa.org/doi/10.2514/6.2011-3504},
	doi = {10.2514/6.2011-3504},
	abstract = {With the retirement of the Space Shuttle, NASA is designing a new spacecraft, called Orion, to fly astronauts to low earth orbit and beyond. Characterization of the dynamic stability of the Orion spacecraft is important for the design of the spacecraft and trajectory construction. Dynamic stability affects the stability and control of the Orion Crew Module during re-entry, especially below Mach = 2.0 and including flight under the drogues. The Launch Abort Vehicle is affected by dynamic stability as well, especially during the re-orientation and heatshield forward segments of the flight. The dynamic stability was assessed using the forced oscillation technique, free-to-oscillate, ballistic range, and sub-scale free-flight tests. All of the test techniques demonstrated that in heatshield-forward flight the Crew Module and Launch Abort Vehicle are dynamically unstable in a significant portion of their flight trajectory. This paper will provide a brief overview of the Orion dynamic aero program and a high-level summary of the dynamic stability characteristics of the Orion spacecraft.},
	publisher = {AIAA Paper 2011-3504},
	author = {Bruce Owens, D. and Aubuchon, Vanessa V.},
	year = {2011},
}

With the retirement of the Space Shuttle, NASA is designing a new spacecraft, called Orion, to fly astronauts to low earth orbit and beyond. Characterization of the dynamic stability of the Orion spacecraft is important for the design of the spacecraft and trajectory construction. Dynamic stability affects the stability and control of the Orion Crew Module during re-entry, especially below Mach = 2.0 and including flight under the drogues. The Launch Abort Vehicle is affected by dynamic stability as well, especially during the re-orientation and heatshield forward segments of the flight. The dynamic stability was assessed using the forced oscillation technique, free-to-oscillate, ballistic range, and sub-scale free-flight tests. All of the test techniques demonstrated that in heatshield-forward flight the Crew Module and Launch Abort Vehicle are dynamically unstable in a significant portion of their flight trajectory. This paper will provide a brief overview of the Orion dynamic aero program and a high-level summary of the dynamic stability characteristics of the Orion spacecraft.

@inproceedings{glass2011,
	title = {Physical challenges and limitations confronting the use of {UHTCs} on hypersonic vehicles},
	doi = {10.2514/6.2011-2304},
	abstract = {Ultra-high temperature ceramics (UHTCs) have been studied for many years as possible material solutions for leading edges of hypersonic vehicles. Over that time, many of the processing and engineering challenges have been addressed. Though UHTCs may have high-temperature capability for some applications, there still remain several physical challenges and limitations confronting their use on hypersonic vehicles. UHTCs possess a very high density, and for weight sensitive vehicles, high density can lead to significant weight concerns. Being monolithic ceramics, UHTCs have thermal shock and fracture toughness concerns that confront all non-fiber-reinforced ceramics. The limitation discussed here for UHTCs is high-temperature oxidation in flight environments. In the temperature range of {\textasciitilde}2900°F ({\textasciitilde}1600°C) and below, Si-based UHTCs form a protective silica (SiO2) layer that helps protect the substrate from oxidation. Above that temperature range, Si-based UHTCs appear to experience similar active oxidation issues that confront structural ceramic matrix composites (CMC) such as C/SiC and coated C/C. Non-Si-based materials should be considered to realize a true step forward in temperature capability with respect to conventional Si-based CMCs.},
	publisher = {AIAA Paper 2011-2304},
	author = {Glass, David E.},
	year = {2011},
}

Ultra-high temperature ceramics (UHTCs) have been studied for many years as possible material solutions for leading edges of hypersonic vehicles. Over that time, many of the processing and engineering challenges have been addressed. Though UHTCs may have high-temperature capability for some applications, there still remain several physical challenges and limitations confronting their use on hypersonic vehicles. UHTCs possess a very high density, and for weight sensitive vehicles, high density can lead to significant weight concerns. Being monolithic ceramics, UHTCs have thermal shock and fracture toughness concerns that confront all non-fiber-reinforced ceramics. The limitation discussed here for UHTCs is high-temperature oxidation in flight environments. In the temperature range of ~2900°F (~1600°C) and below, Si-based UHTCs form a protective silica (SiO2) layer that helps protect the substrate from oxidation. Above that temperature range, Si-based UHTCs appear to experience similar active oxidation issues that confront structural ceramic matrix composites (CMC) such as C/SiC and coated C/C. Non-Si-based materials should be considered to realize a true step forward in temperature capability with respect to conventional Si-based CMCs.

@inproceedings{mcguire2011,
	address = {Orlando, FL},
	title = {Flexible {Ablative} {Thermal} {Protection} {Sizing} on {Inflatable} {Aerodynamic} {Decelerator} for {Human} {Mars} {Entry} {Descent} and {Landing}},
	publisher = {\{AIAA Paper\} 2011-344},
	author = {McGuire, Mary Kathleen and Arnold, James O and Covington, M Alan and Dupzyk, Iain C},
	year = {2011},
}

@article{sheehan2011,
	title = {Emissive probes},
	volume = {20},
	number = {6},
	journal = {Plasma Sources Science and Technology},
	author = {Sheehan, J P and Hershkowitz, N},
	year = {2011},
	pages = {1--22},
}

@article{deschenes2011,
	title = {Effects of {Rotational} {Energy} {Relaxation} in a {Modular} {Particle}-{Continuum} {Method}},
	volume = {25},
	number = {2},
	journal = {Journal of Thermophysics and Heat Transfer},
	author = {Deschenes, Timothy R and Holman, Timothy D and Boyd, Iain D},
	year = {2011},
	pages = {218--227},
}