DEM simulation of oblique shocks in gravity-driven granular flows with wedge obstacles

摘要

Deflecting wedge obstacles are often built to divert hazardous flows away from residential areas that are in the way of harm. When a rapid avalanche flow is deflected by an obstacle, this usually causes abrupt changes in the flow thickness and velocity and exhibits characteristics like oblique shock waves in the aerodynamic system or oblique hydraulic jumps in the open channel flows. In this study, the Discrete Element Method (DEM) is employed to simulate the motion of granular materials impinging on a wedge obstacle in an adjustable inclination chute. We use chutes with four different inclined angles combined with wedge obstacles having different angles to investigate the overall flow behavior. Both the flow velocity and the flow depth are obtained by averaging the numerical simulation data, and then the granular temperature and the shock angle are calculated. The results of the DEM simulation are compared with that of the classical oblique shock theory. We find that there is good agreement between the classical oblique granular shock theoretical calculations and the DEM simulation results. Moreover, the microdynamic variables related to flow structure such as the packing density and the coordination number are also discussed in the present study.