Analysis of oblique wave interaction with perforated caisson breakwaters with partial wave absorption parts

Abstract

This article presents a three-dimensional (3D) iterative analytical solution for water wave interactions with perforated caisson breakwaters with partial wave absorption parts based on linear potential flow theory. A periodic boundary condition is adopted for developing the series solutions of the velocity potentials by the separation of variables method. A quadratic pressure drop condition is imposed on the perforated walls to introduce wave energy dissipation. The unknown expansion coefficients in the velocity potentials are determined by matching the boundary conditions between adjacent fluid domains combined with iterative calculations. The hydrodynamic quantities, including the reflection coefficient, wave forces, and free surface elevation, are estimated. The convergences of the series solutions and the iterative calculation process are examined. The analytical solution calculations agree well with the known analytical and experimental results for special cases in the literature. Variations in the hydrodynamic quantities versus the main influencing factors are clarified. Partial wave absorption concept design enables the hydrodynamic performance of the present caisson breakwater with a smaller perforated wall area to be similar to that of a fully perforated caisson breakwater. To achieve a lower reflection coefficient and wave forces, the ratio of the wave chamber length to the caisson length is suggested to be 0.3–0.5, and the front wave chamber width should be less than half of the total wave chamber width.