Reflection and Transmission of Water Wave by Porous Breakwater

Abstract

A small‐amplitude water wave acting on a vertical porous breakwater in an infinitely long channel is investigated. In the present work, homogeneous water follows conventional assumptions as irrotational, inviscid, incompressible fluid flow. The solid skeleton of the porous breakwater is rigid, and the flow inside the porous breakwater is governed by simplified Biot theory of poroelasticity. A small “porous Reynolds number” is applied to obtain a regular perturbation solution that preserves the surface of seepage on the breakwater/channel flow interface. It is found that there are dramatic variations of velocity distributions among vertical cross sections inside the porous breakwater. It is also found that the reflected wave is greater, while the transmitted wave is less for waves of higher frequency with thicker and less porous breakwaters. However, the thickness of the porous breakwater only has a significant effect on the transmitted wave.