Gravity wave interaction with a composite pile-rock breakwater

Abstract Surface gravity wave interaction with a novel composite pile-rock breakwater having a stack of porous plates fixed on its top is investigated in the present study. A novel numerical code based on dual-boundary-element-method is developed to understand the wave scattering and force coefficients within framework of linearized potential flow theory. Out of the four different proposed configurations (pile-rock alone, vertical, horizontal, and H-shaped porous plate assembly with pile-rock), it is found that a novel H-shaped porous plates with submerged pile-rock are very effective in attenuating the wave energy. The parametric study for the H-shaped configuration with several key aspects like porosity of the permeable plates, submergence depth of the horizontal plate, pile-rock relative height and width of the pile-rock barriers are investigated. Increasing relative rock barrier width from 0.25-0.75 offers only a marginal reduction in wave transmission but increases the vertical wave force on the H-plate barrier almost twice. By changing relative submergence of the horizontal porous plate from, it is possible to reduce wave transmission by about 10% but at the expense of increasing vertical wave force almost 50%-75%. Increasing the pile-rock height helps to reduce the wave transmission but significantly increases horizontal wave force and moment on perforated H-shaped barrier. The results of the parametric study can be used for optimizing the dimensions of pile-rock cum porous plate wave barrier for a wide range of field conditions.