Study On The Interaction Between Oscillatory Flow And Sediments Or Mud

The turbulent bottom layer induced by the wave or wave combined current over rough bed has been received much attention from coastal engineer. Although the thickness of this bottom layer is quite small compared with the water depth, it still play a very important role in determining the sediment suspension and movement, the rate of wave energy dissipation, and the magnitude of bottom shear stress. Therefore, a numerical model is developed to describe the essential feature in the oscillatory bottom layer, and the large eddy simulation technique is used to model the sub-grid scale turbulence effects, the correspondence between the measurement and the simulations seems to be good in all case.When we discuss the interaction between the wave and sediments, the turbulence must be concerned. This paper mainly considers the oscillatory bottom boundary layers over flat or rippled sea beds. Owing to the strong shear and anisotropy of oscillatory flow, an anisotropic turbulence mathematical model is set up using the finite difference method, and the computational results of the model are verified by comparisons with well known experiments. Turbulent energy, dissipation and Reynolds stress can all be computed with this mathematical model, and the development processes of a large coherent vortex structure over a rippled bed, such as main flow separation, coherent vortex formation and curling, coherent vortex ejection and breaking up are successfully simulated.In addition, this paper discussed the turbulence characteristic of oscillatory bottom layer over plane rough bed in detail. It need to study the coherent structure closed the bed and build the new wall boundary condition for mud.