Numerical Simulation Of Solidary Waves And Currents Interaction With Coastal Structures By Unsteady Reynolds Equation Models

In actual coastal environment, wave and current are usually in combined motion. The effects of combined wave and current on the transport of nearshore sands and the safty of coastal structures are more complicated than that of wave or current alone. Therefore, the mechanism of wave interaction with current becomes the frontier of nearlinear science, drawing wildly attention from experts and scientists. It is also significant to the exploiture of the ocean and protection of seashore resources.A two dimensional numerical model for studying the combined action of wave and current on coastal structures is developed in this paper. The Unsteady Reynolds Navier-stokes Equations (URANS) and k ?εTurbulent Models are applied as the governing equations in the model. An active generating-absorbing numerical wave paddle is used to generate waves. The sponge layer is used at the open boundary to absorb the reflected waves. At the free surface, the Youngs'algorithm is adopted to reconstruct the profile of the free surface at every time step.Two-steps projection method is used to calculate the URANS. Firstly, the effect of pressure on velocity is ignored, i.e. a temp velocity field is computed with the pressure term being deleted from the momentum equations. Secondely, the temp velocity is projected into a none-divergent space, and the real veolocity is obtained. In order to validate the numerical models in simulating current and wave interaction with coastal structures, some of the classical examples such as flows passing a circular cylinder, solitary waves running up on a slope, are simulated by the numerical model. The numerical results of current forces and velocity fields agree well with experimental data.The two dimentional model is applied to simulate wave and current interaction with cylinders at different water depthes in several typical conditions. The effects of the free surface on the hydrodynamic characters of the cylinder are analyzed. The structures of the flow and the wave surface deformation near the circular objects are also obtained. The results are useful in designing and management of pipelines near the seabed.