Buoyancy-Driven Two-Layer Exchange Flows Across a Slowly Submerging Barrier
- 47 Downloads
Results are presented from a combined analytical and laboratory study of unsteady, two-layer, density-driven, sub-maximal exchange over a slowly-descending estuarine barrier located very close to the junction of the river mouth and the near-shore coastal zone. As in the precursor study (Cuthbertson et al. 2004, Environ. Fluid Mech. 4, 127–155) that the present investigation extends, the rate of descent of the barrier is assumed to be sufficiently slow for the unsteady exchange flow to adjust continuously to the appropriate quasi-steady conditions at every stage of the descent. The results demonstrate that the thickness of each layer at the barrier crest can be predicted satisfactorily by a hydraulic analysis that (i) assumes the existence of a single control point at the barrier crest and (ii) incorporates the hydraulic losses arising from the sudden expansion and contraction of the upper and lower layers, respectively, at the channel exit. Predictions of the normalised elevations of the interface at the barrier and exit for the “inviscid” maximal exchange case are shown to coincide with the maximal exchange predictions of Zhu and Lawrence (2000, J. Hydraul. Eng. ASCE 126(12), 921–928).
Keywordsbuoyancy mixing stratification sub-maximal exchange two-layer flow
Unable to display preview. Download preview PDF.
- 1.Coates, M.J., Guo, Y., Davies, P.A. 2001Laboratory model studies of flushing of trapped salt water from a blocked tidal estuaryJ. Hydraulic Res.39601609Google Scholar
- 2.Donnelly, B., Hamill, G.A., Robinson, D.J., MacKinnon, P., Johnston, H.T. 2000Interfacial layer development due to turbulent mixing at a density interfaceLawrence, G.A.Pieters, R.Yonemitsu, N. eds. Proceedings of 5th International Symposium on Stratified FlowsUniversity of British ColumbiaVancouver853858Google Scholar
- 4.Zhu, D.Z., Lawrence, G.A. 2000Hydraulics of exchange flowsJ. Hydraul. Engng. ASCE126921928Google Scholar
- 5.Dalziel, S.B. 1991Two-layer hydraulics: a functional approachJ. Fluid Mech.223135163Google Scholar
- 6.Baines, P.G. 1998Topographic Effects in Stratified FlowsCambridge University PressCambridge, UK.Cambridge Monographs in MechanicsGoogle Scholar
- 7.Miller, D.S. eds. 1996Internal Flow Systems2BHR Group LtdCranfield, UKGoogle Scholar