Boundary Integral Formulation of Wave Energy Dissipation in Porous Media

Abstract

When gravity waves interact with porous media, a significant portion of the kinetic energy is dissipated inside the pores due to turbulence and friction. It is important to estimate such energy loss when designing porous ocean structures, such as rubble-mound breakwaters in which the wave energy dissipation is usually the major goal. In this paper, the energy dissipation process is numerically modeled with the Boundary Integral Element Method (BIEM). To apply the BIEM efficiently, a boundary integral formulation for the wave energy dissipation has been developed, based on energy-flux deficit concept, to replace the commonly used volumetric expression (Sulisz [7], Madsen [5], and Sollitt et al.[6]).

The numerical model, which combines BIEM, the nonlinear-unsteady porous flow model and the boundary integral formula of wave energy dissipation, is capable of simulating the complex interaction process of waves with porous media of complex geometry for the full range of permeability. Compared to the conventional volumetric formulation, the boundary integral formulation for the energy dissipation is proved to be a very efficient when applied with the BIEM.