A Coarse-Grained Discrete Element Model (CG-DEM) based on parameter scaling for dense wet granular system

The Discrete Element Model (DEM) is widely used for studying wet granular systems, where particles experience liquid bridge forces. However, due to its high computational cost, DEM is not a viable approach for industrial scale simulations. A potential solution is offered by coarse-graining (CG), where a group of particles is substituted by a larger particle, thereby increasing the computational efficiency of the simulations. However, it is essential to consider appropriate scaling rules to properly apply CG-DEM and conserve the material's rheological behaviour. Two scaling approaches based on constant dimensionless groups, Weber (We) and Bond (Bo) numbers, are compared. The We-based CG-DEM simulation can reproduce the volume fraction, velocity, apparent viscosity and macroscopic friction fields properly, but not granular temperature. The effect of CG on the liquid convection and migration patterns, as well as wall coverage is explored. In addition, the applicability of the CG-DEM model in the wet slumping regime is investigated.