Time-Dependent Two-Layer Hydraulic Exchange Flows

Open Access
Publisher Website
Google Scholar
Abstract
A theory is presented for time-dependent two-layer hydraulic flows through straits. The theory is used to study exchange flows forced by a periodic barotropic (tidal) flow. For a given strait geometry the resulting flow is a function of two nondimensional parameters, γ = (g′H)1/2T/L and qb0 = ub0/(g′H)1/2. Here g′, H, L, T, and ub0 are, respectively, the reduced gravity, strait depth and length scales, the forcing period, and the barotropic velocity amplitude; γ is a measure of the dynamic length of the strait and qb0 a measure of the forcing strength. Numerical solutions for both a pure contraction and an offset sill-narrows combination show that the exchange flow, averaged over a tidal cycle, increases with qb0 for a fixed γ. For fixed qb0 the exchange increases with increasing γ. The maximum exchange is obtained in the quasi-steady limit γ→∞. The minimum exchange is found for γ→0 and is equal to the unforced steady exchange. The usual concept of hydraulic control occurs only in these two limit... Abstract A theory is presented for time-dependent two-layer hydraulic flows through straits. The theory is used to study exchange flows forced by a periodic barotropic (tidal) flow. For a given strait geometry the resulting flow is a function of two nondimensional parameters, γ = (g′H)1/2T/L and qb0 = ub0/(g′H)1/2. Here g′, H, L, T, and ub0 are, respectively, the reduced gravity, strait depth and length scales, the forcing period, and the barotropic velocity amplitude; γ is a measure of the dynamic length of the strait and qb0 a measure of the forcing strength. Numerical solutions for both a pure contraction and an offset sill-narrows combination show that the exchange flow, averaged over a tidal cycle, increases with qb0 for a fixed γ. For fixed qb0 the exchange increases with increasing γ. The maximum exchange is obtained in the quasi-steady limit γ→∞. The minimum exchange is found for γ→0 and is equal to the unforced steady exchange. The usual concept of hydraulic control occurs only in these two limit...

This publication has 0 references indexed in Scilit: