Numerical and experimental studies on the hydrodynamic performance of a composite cylindrical perforated-wall caisson breakwater

This study examines the hydrodynamic performance of a new caisson-type breakwater, characterizing a composite cylindrical perforated-wall caisson (CCPC) that significantly suppresses the wave energy reflection and reduces wave forces. A comprehensive numerical analysis of the interaction between waves and the caisson breakwater was conducted using a 3-D numerical wave flume established with OpenFOAM (R). For validating the numerical model, experimental tests were conducted to measure the free surface elevations during waves interacting with the CCPC. The effects of different front wall shapes of caissons on hydrodynamic performance in terms of free surface elevations and flow fields at the joint were illustrated. Subsequently, the effects of structural parameters, the relative wave chamber width and porosity, on the hydrodynamic performance of the caisson were illustrated by investigating free surface elevations, velocity vectors, vorticity map, and wave pressure distributions. An empirical formula for predicting the reflection coefficient of the CCPC was proposed. Moreover, to estimate the stability of the breakwater, the wave forces acting on components of the CCPC were contrastively analyzed. The results suggest that the caisson, characterized by a rhythmic shape of the front wall, effectively dissipates wave energy while maintaining structural stability.