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Unsteady two-layer hydraulic exchange flows with friction

Published online by Cambridge University Press:  25 August 2009

S. S. LI  and
G. A. LAWRENCE
S. S. LI*
Affiliation:
Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec, CanadaH3G 1M8
G. A. LAWRENCE
Affiliation:
Department of Civil Engineering, University of British Columbia, Vancouver, BCCanadaV6T 1Z4
*
†Email address for correspondence: samli@bcee.concordia.ca.
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Abstract

Two-layer exchange flow through a contraction with both friction and barotropic forcing is modelled in terms of three parameters reflecting the friction and the strength and period of the barotropic forcing. In the appropriate limits, the results for steady flow with and without friction, and inviscid barotropically forced flow are recovered. The predicted time-dependent interface position compares well with laboratory experiments, improving on the inviscid formulation. The concurrent effects of friction and barotropic forcing on average exchange flow rate are determined. When friction is weak barotropic forcing increases the exchange rate. However, when friction is high, tidal forcing can result in a reduced exchange rate, a phenomena that we call tidal inhibition. When friction is weak maximal exchange occurs throughout the tidal cycle, but as friction is increased submaximal flow develops for longer and longer periods. As friction is increased even further the flow becomes hydraulically uncontrolled. The parameter range for major sea straits includes tidally enhanced and tidally inhibited flows, as well as maximal, submaximal and uncontrolled flows.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 633 , 25 August 2009 , pp. 99 - 114
Copyright
Copyright © Cambridge University Press 2009

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