Quasi-two-dimensional shallow shear flows in rivers and oceans

It is shown in this paper how the large-scale mixing process in rivers and oceans can be correctly simulated by a two-length-scale turbulence model. The turbulence in the shear how must be divided into a large-scale component and a small-scale component. The two components are then determined by separated models. In the model formulation, friction is recognized as a body force responsible for the direct transfer of energy from the large-scale turbulence to the small-scale turbulence. The friction as a body-force effect on the large-scale turbulence in the shallow shear how is found to be similar to the buoyancy effect on the gravity stratified hows.