SPH Model For Nonlinear Wave-Permeable Structure Interaction

Waves interaction with porous structures involve wave reflection, wave transformation, wave breaking and wave overtopping as well as many nonlinear physical effects such as turbulent flow, seepage flow and wave energy dissipation. It is a very complicated issue of nonlinear seepage flow. With the global climate warming and sea level rising, the marine disasters for coastal protection structures are also growing in recent years. Therefore there are important scientific significance and practical value to further study waves interaction with permeable structures.The CSPM is introduced to solve the disorder particle distribution and pressure field at the free water surface. A new pressure computing method for solid particle is presented to overcome fluid particles moving away or penetrating solid boundaries. In addition, the hybrid OpenMP-MPI parallel algorithm is developed to crack the bottleneck problem of the low efficiency for large-scale computing. Combined with the numerical wave generation and wave absorbing technique as well as periodic lateral boundary, this paper established the 2D/3D numerical wave tank based on the parallel SPH model for simulating accurately the nonlinear wave interaction with coastal structure.Based on the nonlinear seepage constitutive relation, the SPH method is extended to the nonlinear seepage mechanics field. The 2D and 3D SPH porous models are established for the simulation of nonlinear wave moving through the permeable structures. The models are based on the VAFANS equations in which the SPS turbulence stresses are calculated using an eddy viscosity type model. The resistant forces on the fluid flow caused by the presence of the solid skeleton are expressed in the standard empirical linear and nonlinear forms. By adopting the apparent density concept and defining the porosity information in a series of background porosity points, the entire domain can be solved simultaneously using the same form of governing equations. The continuity of the velocities and the pressures at the interface is ensured by setting a narrower transition zone where the porosity and the apparent density changes gradually with a relatively larger gradient.A series of numerical experiment results show that the 2D/3D SPH porous models are accurate for simulating dam-break wave propagation in permeable dam, wave attenuation on the seabed of different permeability, wave evolution and flow field distribution around the Low-crested Porous Structures and shore-parallel breakwater.