A resolved CFD–DEM approach for the simulation of landslides and impulse waves

Abstract

Landslides and subsequent impulse waves could result in destructive hazards, while most of the existing simulation methods are dependent on over simplifications or excessive hypothesis due to the numerical difficulties. In order to elaborately present the phenomenon of the strong coupling and the mechanism of the energy transfer between the fluid phases and the landslides, a novel resolved computational fluid dynamics-discrete element method (CFD–DEM) is proposed in this paper. The fluid phases, including the water and the air, are governed by the full Navier–Stokes equations in the Eulerian framework, whereas the landslide motion is modeled by the discrete element method using the Lagrangian description. The key challenge, namely the representation of the moving interfaces between the fluid and the landslides in different frameworks, is handled by the immersed boundary method. Meanwhile, the free surface of the impulse waves between the water and the air is captured by the conservative Level Set method, and the coupled system is solved by the partitioned method in an iterative way to obtain the strong coupling effect. Compared with the unresolved CFD–DEM method, the proposed approach calculates the fluid field with high resolution and reflects the mutual interaction precisely. After the verification of the overall performance by two benchmark cases, the resolved CFD–DEM method is applied to simulate the landslide movement and the subsequent generated waves in the Lituya Bay.