DEM and DEM-CFD modeling of systems with geometric constrictions using a new particle location based multi-level coarse graining approach

Abstract

A popular Lagrangian approach for modeling granular systems is the discrete element method (DEM). Currently, the simulation of industrial granular systems often exceeds modern computer capacities. Therefore, the coarse graining (CG) approach bundles multiple particles into grains, which are less computationally demanding due to the reduced number of entities considered. In systems, where the maximum grain size is limited by local geometry constrictions, uniform grain sizes lead to inefficient computations since far from the constrictions larger grain sizes could be reasonably used. Multi-level coarse graining (MCG) addresses this by using multiple grain sizes, which are adapted to the geometric constrictions. In this study, geometrical non-uniform hoppers and a Wurster coater system were modeled using a new MCG approach. Results from literature regarding hopper discharge were matched. For the Wurster coater system MCG outperforms conventional CG by providing a higher resolution of the granular material close to the geometric constriction.