Wave-induced flow in a porous vertical breakwater

摘要

A study is conducted to evaluate the wave induced porous flow in a vertical permeable breakwater. Experiments were performed in a two-dimensional wave tank to study the wave-induced particle motion in a vertical porous breakwater model. The water surface levels were recorded on both sides of the breakwater and a video camera was employed to monitor the motion of small particles inside the porous media. The trajectory of a particle is classified here into six patterns due to the chaotic motion in the pores. A variety of incident wave conditions aid various properties of the porous media were examined in the experiment to explore their influence on the water particle motion inside a porous medium. A coupled BEM-FEM model, developed by the authors. s also adapted to compute the porous flow parameters in the breakwater as well as the wave deformation in its vicinity. Comparisons hove been made between the numerical and experimental results of water surface levels around the breakwater and the average displacement of a particle in the porous media. It has been found that the numerical model predicts well the wave deformation and provides a reasonable Cs mate of the particle motion in the porous media. Longer and higher waves have been found to be very efficient in causing larger net horizonta1 displacement of the particles. On the other hand, larger porosity and/or diameter of solids in the porous media are found to cause less chaotic the motion and larger net displacement of the particles.