The perforated caissons are widely used to decrease wave force and reflection effectively in costal engineering. The nonlinear interactions between waves and partially perforated caissons are investigated using the weakly compressible Smoothed Particle Hydrodynamic (WCSPH) method. An improved algorithm based on the dynamic boundary particles (DBPs) is proposed to treat the solid boundary. The performance of the model is validated by the analytical solution of the surface elevations and wave pressures in front of the vertical wall. The SPH results of the reflection coefficients of the perforated caissons are compared with the available experiment data and good agreements are obtained. The wave pressures on the perforated front wall and the rear wall are analyzed. The effects of the relative wave chamber width B/Lc and the porosity of the perforated wall on the wave energy dissipation of the perforated caissons are discussed.
Perforated breakwaters are good alternatives to traditional non-permeable breakwaters and are used in offshore and coastal areas of circulation considerations. Compared with the conventional non-permeable caissons, the perforated caissons have such advantages as the reduced environmental impact and good performance of dissipating the wave energy. These positive effects enhanced the application of the perforated caissons of various opening types during the last decades. The knowledge of the forces acting on the caissons and the mechanism of wave dissipation are required for its design. There are few numerical studies for wave-perforated caisson interaction based on grid methods in the literatures because of the difficulties of dealing with strong nonlinear free surface and the opening pore.
Being a meshfree Lagrangian method, the Smoothed Particle Hydrodynamics model does not require the explicit surface capturing scheme in treating strong nonlinear flows with large free surface deformation and enables the easy modeling of coastal structures with complex geometrical boundaries. Recently SPH has attracted favorable attention in ocean and coastal engineering and been utilized to solve a variety of nonlinear problems involving wave slamming, liquid sloshing and fluid-structure interaction (Gao et al., 2012; Ren et al., 2015; Shao et al., 2012). Very recently Meringolo et al. (2015) used the diffusive weakly-compressible SPH to simulate wave loads and hydraulic characteristics of the perforated breakwaters.