Three-Dimensional Nature of Flow near a Sill. Klymak, J. M. & Gregg, M. C. J. Geophys. Res. Oceans, 106(C10):22295–22311, 2001.
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Velocity and density sections across Knight Inlet, British Columbia, demonstrate that lateral recirculations are a first-order feature of the flow in the lee of the sill. The flow over this sill has been used as a typical example of two-dimensional hydraulics, with a lower layer that thins and accelerates as it moves downstream below an almost stagnant layer that widens downstream, creating a distinctive wedge shape. However, we find that rather than being stagnant, the velocity in this wedge-shaped layer is actually quite large, consisting of a swiftly recirculating dipole vortex during flood tide and a monopole vortex during ebb tide, though we may have missed the matching half of a dipole with our sampling during ebb. The recirculations during flood tide carry an amount of water equal to 25% of the tidal flux, while the monopole during ebb tide carries 20% of the tidal flux. These recirculations bias along-channel estimates of volume flux, especially in the middle wedge-shaped layer, and demonstrate that accurate volume fluxes in the lee wave are only possible if three-dimensional surveys are made. Our three-dimensional survey shows that there is a net isopycnal convergence of water in the middle layer at a rate adequate to close the volume budget of the flow without recourse to diapycnal fluxes. We also calculate the strength of the vorticity in the recirculations observed during flood tide and attribute their formation to boundary layer separation.
@Article{	  klymakgregg01a,
  Title		= {Three-Dimensional Nature of Flow near a Sill},
  Author	= {Klymak, Jody M. and Gregg, Michael C.},
  Year		= {2001},
  Journal	= {J. Geophys. Res. Oceans},
  Volume	= {106},
  Number	= {C10},
  Pages		= {22295--22311},
  DOI		= {10.1029/2001JC000933},
  URLDate	= {2024-11-21},
  Abstract	= {Velocity and density sections across Knight Inlet, British
		  Columbia, demonstrate that lateral recirculations are a
		  first-order feature of the flow in the lee of the sill. The
		  flow over this sill has been used as a typical example of
		  two-dimensional hydraulics, with a lower layer that thins
		  and accelerates as it moves downstream below an almost
		  stagnant layer that widens downstream, creating a
		  distinctive wedge shape. However, we find that rather than
		  being stagnant, the velocity in this wedge-shaped layer is
		  actually quite large, consisting of a swiftly recirculating
		  dipole vortex during flood tide and a monopole vortex
		  during ebb tide, though we may have missed the matching
		  half of a dipole with our sampling during ebb. The
		  recirculations during flood tide carry an amount of water
		  equal to 25\% of the tidal flux, while the monopole during
		  ebb tide carries 20\% of the tidal flux. These
		  recirculations bias along-channel estimates of volume flux,
		  especially in the middle wedge-shaped layer, and
		  demonstrate that accurate volume fluxes in the lee wave are
		  only possible if three-dimensional surveys are made. Our
		  three-dimensional survey shows that there is a net
		  isopycnal convergence of water in the middle layer at a
		  rate adequate to close the volume budget of the flow
		  without recourse to diapycnal fluxes. We also calculate the
		  strength of the vorticity in the recirculations observed
		  during flood tide and attribute their formation to boundary
		  layer separation.},
  copyright	= {All rights reserved},
  langid	= {english},
  Keywords	= {jmkrefereed},
  File		= {/Users/jklymak/Zotero/storage/HD8NKM8D/Klymak and Gregg -
		  2001 - Three-dimensional nature of flow near a
		  sill.pdf;/Users/jklymak/Zotero/storage/AYRQN8RA/2001JC000933.html}
}

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