Simulation of free surface recirculating flows in semi-enclosed water bodies by a k–ω model

The flow patterns in semi-enclosed water bodies with free surfaces generally consist of free or forced recirculations which can have significant effect on the water quality and fluid exchange. To accurately predict the flow structures in these water bodies a three-dimensional layer-integrated numerical model has been developed. The turbulence (consisting of the free shear component and the bottom friction component) is parametrized by the k–ω equations. The governing equations are split into three parts in the finite difference solution: advection, dispersion and propagation. The advection part is solved by the four-node minimax-characteristics scheme. The dispersion part is solved by the central difference method and the propagation part is solved implicitly by using the Gauss–Seidel iteration method to overcome the restrictive Courant–Friedrich–Lewy (CFL) stability constraint. The model has been verified against the laboratory data on forced recirculating flow in a physical model harbour and on free recirculating flow in an expanded channel.