Drift current under the combined action of wind and waves in shallow water

Document Type

Conference Proceeding

Date of Original Version

1-1-1994

Abstract

In the present study the conservation of momentum and turbulent energy equations are solved using an implicit finite difference method to predict the vertical distribution of current, turbulent energy, and eddy viscosity at one point for shallow water. The model includes coupling between the wave and wind induced currents. Input energy from the atmosphere to the turbulent energy and current fields is represented through free surface boundary conditions. The model was applied to predict the surface drift for water depths ranging from 20 to 1000 m for varying wind speeds. The predicted steady state drift factor decreases with decreasing water depth for a given wind speed. For depths greater than 400 m (deep water) or shallower than 100 m (shallow water), the drift factor is depth independent. In deep (shallow) water, the drift factor decreases (increases) with increasing wind speed. The deflection angle is relatively insensitive to variations in water depth, but decreases slightly as wind speed increases. Model results can be explained by studying the vertical eddy viscosity profiles and whether it is dominated by surface or bottom generated turbulence. Model results are consistent with observations and earlier theoretical studies and show drift factors/deflection angles typically varying from 1.5 to 4%, and 10 to 25°, respectively.

Publication Title, e.g., Journal

Proceedings - 17th Arctic and Marine Oil Spill Program Technical Seminar 1994

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