Three-dimensional discrete element models for the granular statics and dynamics of powders in cavity filling

Rapid granular flow from a moving container and angle of repose formation were investigated by numerical simulations using the discrete element method (DEM) and experiments. Grain models of various geometrical complexity were studied and their ability to reproduce the experiments in those regimes was explored. The predictive power of the most realistic model for gravity driven cavity filling was assessed. Good agreement between computed and measured density distributions within the filled cavities provides a basis for numerical process variations aiming at homogenized density distributions. The effect of numerical coarse graining was found to be negligible for all properties of interest provided that force laws are scaled properly and corrections for boundary effects are taken into account. The proposed scaling was tested for a certain set of force laws but could be applied to different DEM forces as well. An analytic mass flow law for powder discharge from a moving container was derived and verified by our DEM simulations.