Flow Separation of Currents in Shallow Water

by Richard P. Signell, U.S. Geological Survey, United States,

Document Type: Proceeding Paper

Part of: Estuarine and Coastal Modeling


Flow separation of currents in shallow coastal areas is investigated using a boundary layer model for two-dimensional (depth-averaged) tidal flow past an elliptic headland. If the shoaling region near the coast is narrow compared to the scale of the headland, bottom friction causes the flow to separate just downstream of the point where the pressure gradient switches from favoring to adverse. As long as the shoaling region at the coast is well resolved, the inclusion of eddy viscosity and a no-slip boundary condition have no effect on this result. An approximate analytic solution for the pressure gradient along the boundary is obtained by assuming the flow away from the immediate vicinity of the boundary is irrotational. On the basis of the pressure gradient obtained from the irrotational flow solution, flow separation is a strong function of the headland aspect ratio, an equivalent Reynolds number, and a Keulegan-Carpenter number.

Subject Headings: Pressurized flow | Flow separation | Water flow | Shallow water | Two-dimensional flow | Boundary layers | Fluid flow | Tides

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