Coupled particle-fluid numerical simulation model for internal erosion of granular soils with a broad particle size distribution

This study presents a coupled particle-fluid numerical simulation model for the internal erosion of granular soils with a broad particle size distribution in order to investigate the mechanisms of the motion of fine soil particles inside the matrix of coarse soil particles from a microscopic point of view. In the model, the Discrete Element (DE) method and the Lattice Boltzmann (LB) method are employed for the soil particles and for the seepage flow, respectively. On the basis of the coupled DE-LB model, two types of coupling schemes are newly combined. The coarse soil particles are simulated by the microscale-coupled method where the fluid flow is modeled at smaller scales than the soil particle diameter, while the fine soil particles are simulated by the macroscale-coupled method where the fluid flow is modeled at larger scales than the soil particle diameter. 2-D and 3-D simulations of suffusion are performed, and the applicability of the proposed model to the internal erosion of granular soils is validated.