Diffraction of Solitary Waves by Breakwaters

Abstract

The diffraction of solitary waves around the end of a straight, thin breakwater in water of uniform depth is investigated. Results of normal and oblique interactions between solitary waves and a breakwater are presented. For solving this fully three‐dimensional strong‐interaction problem, the generalized Boussinesq (GB) two‐equation model is applied to calculate the flow field and the free‐surface elevation. Following the incident solitary waves impinging on a breakwater, the subsequent evolution of the transmitted, reflected, and diffracted wave fields are numerically evaluated. It is found that after interaction with the breakwater, an initially plane solitary wave is diffracted as a three‐dimensional cylindrical solitary wave and propagates with nonuniform amplitude toward the shadow region. For waves propagating normally past a breakwater, the amplitude of the diffracted wave in the sheltered region is reduced by about 60% in comparison with the initial wave amplitude when the leading diffracted wave reaches the middle portion of the breakwater. The newly evolved secondary backscattered and forward‐scattered waves generated from the tip of the breakwater propagate outward and follow the leading reflected wave and diffracted wave, respectively. The present results are in good agreement with experimental data.