Efficient methods free of irregular frequencies in wave and solid/porous structure interactions

Abstract

The method of boundary integral equation is widely applied to compute and analyze wave–structure interactions in marine and offshore engineering, and the application is also seen in marine aquaculture to deal with waves and porous structure interactions. The application of the Fredholm integral equation of the second kind together with the free-surface Green function for a surface-piercing body suffers from irregular frequencies which may be confused with resonance peaks. A simple and efficient method to remove irregular frequencies in the wave–structure interactions is developed via enforcing null potential (and horizontal derivatives) on discrete points on the interior water-plane area and is referred to as overdetermined integral equations (and enhanced overdetermined integral equations), respectively. Structures with solid surface, porous surface and their blending are considered, and numerical results demonstrate the effectiveness of this method. In contrast to extended integral equations, the overdetermined integral equations are easy to implement and more time-efficient.