Coupled CFD–DEM simulation of fluid–particle interaction in geomechanics

This paper presents a coupled Computational Fluid Dynamics and Discrete Element Method (CFD–DEM) approach to simulate the behaviour of fluid–particle interaction for applications relevant to mining and geotechnical engineering. DEM is employed to model the granular particle system, whilst the CFD is used to simulate the fluid flow by solving the locally averaged Navier–Stokes equation. The particle–fluid interaction is considered by exchanging such interaction forces as drag force and buoyancy force between the DEM and the CFD computations. The coupled CFD–DEM tool is first benchmarked by two classic geomechanics problems where analytical solutions are available, and is then employed to investigate the characteristics of sand heap formed in water through hopper flow. The influence of fluid–particle interaction on the behaviour of granular media is well captured in all the simulated problems. It is shown in particular that a sand pile formed in water is more homogeneous in terms of void ratio, contact force and fabric anisotropy. The central pressure dip of vertical stress profile at the base of sandpile is moderately reduced, as compared to the dry case. The effects of rolling resistance and polydispersity in conjunction with the presence of water on the formation of sandpile are also discussed.