3d numerical simulation of turbulent shallow-water flow in Square Harbor

Three-dimensional computations of a homogeneous shallow-water cavity flow in a square harbor were carried out. The turbulent flow was driven by a stationary current in an adjacent model river. The standard single-length-scale k-epsilon turbulence was found to underestimate the effective horizontal eddy viscosity in the mixing layer. To model the nonisotropic behavior of the flow, a two-length-scale turbulence model has been implemented by adding a depth-averaged k-epsilon model to the existing numerical model TRISULA. This model accounts for large scale turbulence generated in the mixing layer by horizontal shear. Comparison with experimental results showed a significant improvement of the computational results while the increase in computational costs was negligible.