Dual BEM for wave scattering by an H-type porous barrier with nonlinear pressure drop

In this paper, wave scattering by an H-type porous barrier having nonlinear pressure drop boundary condition is analysed within the framework of small amplitude water wave theory. The H-type barrier is constructed using multiple thin (near zero thickness) rigid porous plates which are termed degenerate boundaries. The boundary value problem is solved using an iterative dual boundary element method. Different barrier configurations are analysed and compared to demonstrate the improved hydrodynamic performance of the H-type barrier. Further, the effect of porosity, relative spacing, the relative depth of submergence of the horizontal plate, wave steepness, and the rotation of the horizontal plate is investigated parametrically. Several results such as scattering coefficients (reflection, transmission, and energy-loss) and force coefficients (horizontal, vertical, and moment) are presented to understand the feasibility of the H-type barrier in real field applications. It is revealed that the increase in the structure porosity consistently increases the wave transmission, but reduces wave reflection, and force coefficients. Further, an increase in the relative spacing between the vertical barriers reduces the wave transmission by 20% without increasing the horizontal wave force but at the expense of increasing the vertical force coefficient in the shallow water regime. The results of this study are expected to be useful for the appropriate selection of different structure parameters to optimize the design.