Numerical Study of Wind-Induced Water Currents

A circulation model is developed and used to study wind-induced currents. A new analytical solution, which is independent on the ratio of bottom to surface shear velocity or shear stress, is derived for the steady shear-induced turbulent flow. The simulations for steady countercurrent flows are calibrated with the corresponding analytical solutions, and verified using the experimental results obtained in air-water tunnels. With the aid of the numerical model, the developing process of a shear-induced turbulent flow, the wind-induced setup and seiche are examined. Sensitivity studies reveal that the horizontal eddy viscosity is insignificant, while the magnitude and distribution of vertical eddy viscosity is very important to simulate the vertical velocity distribution. A high-resolution vertical grid must be used near the surface and bottom regions to obtain the detailed and accurate current structure. The results from this study indicate the importance of the three-dimensional circulation model in studying the vertical structure of the wind-induced current, and gives credibility in applying this model in lakes and estuaries.