Numerical study on performance of submerged permeable breakwater under impacts of multi-directional focused wave groups

Multi-directional waves focusing is considered a crucial method for generating extreme waves, posing a significant threat to coastal infrastructure and personal property. In recent years, there has been widespread construction of permeable submerged breakwaters as a preventive measure against extreme wave damage. Therefore, this study aims to assess the attenuation of multi-directional focused waves by both permeable and impermeable submerged breakwaters based on nonhydrostatic numerical wave model (NHWAVE). Effects of several key parameters are carefully examined. According to research findings, permeable submerged breakwaters offer significant benefits in reducing the wave amplitude, flow velocity, water elevation, and energy flux of multi-directional focused wave groups, while also effectively inhibiting the transfer of wave energy to higher frequencies. Additionally, we observe alternating positive and negative vortices occur at the boundary of the permeable submerged breakwater. The findings of this study are expected to advance the investigation into the hydrodynamic characteristics of submerged permeable breakwaters subjected to focused waves.