Fully Coupled Simulation of Interactions Among Waves, Permeable Breakwaters and Seabeds Based on N-S Equations

Interstitial flows in breakwater cores and seabeds are a key consideration in coastal and marine engineering designs and have a direct impact on their structural safety. In this paper, a unified fully coupled model for wave-permeable breakwater-porous seabed interactions is built based on an improved N-S equation. A numerical wave flume is constructed, and numerical studies are carried out by applying the finite difference method. In combination with a physical model test, the accuracy of the numerical simulation results is verified by comparing the calculated and measured values of wave height at measurement points and the seepage pressure within the breakwater and seabed. On this basis, the characteristics of the surrounding wave field and the internal flow field of the pore structure, as well as the evolution process of the fluctuating pore water pressure inside the breakwater and seabed, are further analyzed. The spatial distribution of the maximum fluctuating pore water pressure in the breakwater is compared between two cases by considering whether the seabed is permeable, and then the effect of seabed permeability on the dynamic pore water pressure in the breakwater is clarified. This study attempts to provide a reference for breakwater design and the protection of nearby seabeds.