3D Numerical Simulation Of Nearshore Wave-induced Currents

As wave propagates to the shallow water, wave heights will increase due to shoaling. Then wave breaking will occur as the wave steepness is too large, accompanied by strong turbulence and mixing which will induce the nearshore currents and engineering problems.In this paper, a new 3D nearshore wave-induced current model is established on the basis of the FVM-OSHER model and by introducing the 3D radiation stress terms and the shear stress terms induced by surface rollers into the 3D shallow water equation. Turbulence due to wave breaking and wave-current co-existing bottom friction effect are also considered in the model. The undertow and longshore current have been simulated with the new model, and the numerical results agree with the experimental data.The effect of the turbulence production due to wave breaking and the shear stress induced by surface rollers to the vertical profile of the undertow have been analyzed. It is shown that the numerical results are closer to the experimental data after these two terms are introduced to the model. The effect of roughness coefficient has been analyzed and the range of roughness coefficient for the computational case has been suggested.