Wave Scattering by Twin Surface-Piercing Plates Over A Stepped Bottom: Trapped Wave Energy and Energy Loss

To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surfacepiercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM and the associated toolbox waves2Foam. The volume of fluid (VOF) method was employed to capture the free surface in the time domain. The validation of the present numerical model was performed by comparing with both the analytical and experimental results. The effects of the spacing between two plates and the configuration of stepped bottom on the hydrodynamic characteristics, such as reflection and transmission coefficients, viscous dissipation ratio, and relative wave height between the plates (termed as trapped wave energy), were examined. Moreover, the nonlinear effects of the incident wave height on the hydrodynamic characteristics were addressed as well. The results show that the step configuration can be tuned for efficient-performance of wave damping, and the optimum configurations of the step length B, the step height h(1) and the spacing b, separately equaling lambda/4, 3h/4, and 0.05h (lambda and h are the wavelength and the water depth, respectively), are recommended for the trapping of wave energy.