Development of Three-Dimensional Combined Layer and Level Hydrodynamic Model

Three-dimensional combined layer and level hydrodynamic model is developed using an Alternating Direction Implicit (ADI) finite difference scheme, and the model is tested for a uni-nodal standing wave in a rectangular basin. The model results for the surface elevation and the velocities coincide with the analytical results. The model's ability is tested for a various wind stress and bottom friction in a closed basin with a slip bottom boundary condition. According as the wind stress decreases, the time required for the model to obtain converged and numerically stable solutions is short. The velocity generated by the wind of 10 m/s reaches stable state after 4 hours. The wind-driven velocity near surface is of wind speed, and the velocity near bottom layer is of the surface velocity. Upper layer currents are in the wind direction, whereas lower layer currents are in the opposite direction to maintain mass balance in the closed basin. The salinity distribution near surface increases with time, whereas the distribution near bottom layer decreases with time. The results from this study indicate the importance of the three-dimensional circulation model in studying the vertical structure of the wind-driven current, and gives credibility in applying this model in estuaries and coastal area. This 3-D model is able to simulate the features of the wind-driven countercurrent flow, and wind setup and seiche as well.