Numerical simulation for coastal morphodynamics using DEM-MPS method

Abstract

Numerical simulations were performed for morphodynamics with free water surface fluctuation using the DEM-MPS method, which employs the discrete element method (DEM) and the enhanced moving particle semi-implicit (MPS) method for the solid and liquid phases, respectively. The reproducibility of the DEM-MPS method to a swash ripple formation process of a mixed grain bed is demonstrated. There, the bed is fully covered with water, and its void is filled with pore water. It is suggested that the ripple formation with coarse-grained particles activates the momentum exchange in the surface layer of the movable bed. In addition, a numerical simulation for a solitary wave induced by a landslide by DEM solid particles was carried out. Here, the applicability of the model in the situation where the pore water surface exists in a moving and deforming solid-sediment layer is examined. The simulation results show that it is essential to apply the apparent volume to a fluid particle inside a solid-sediment layer to predict the water surface evolution accurately.