Wave Interaction with Porous Vertical Breakwater in Two-layer Fluid

In this paper, the two-layer fluid model is used to investigate the wave interaction with porous vertical breakwater resting on permeable seabed in two-layer fluid. Based on the Biot seepage consolidation theory and linear wave theory, the analytical solutions to the wave potentials and the seepage pressures inside permeable seabed induced by surface wave and inner wave are derived by applying eigenfunction expansion approach. And accordingly, the analytical expressions of wave-induced uplift force and overturning moment acting on the bottom of porous breakwater are obtained. Numerical results are presented to illustrate the seepage loads caused by inner wave may have same order of magnitude as that induced by surface wave, and the wave-induced seepage loads may have the same order of magnitude as direct wave loads. It is found that the porosity of the breakwater surface may lead an obvious reduction in direct wave loads on breakwater and a certain reduction in wave-induced seepage loads on the bottom of breakwater, especially, lead to a significant reduction in the inner wave-induced overturn moment.