In this study hopper discharge experiments with wood pellets were conducted. The experimental bulk density, flow behavior and discharge rate were compared to corresponding 3-dimensional discrete element simulations with both multi-sphere and polyhedral approximations of the pellet geometry. Additionally a numerical sensitivity analysis for the particle-wall friction was made in order to evaluate the influence of this parameter on hopper discharge in the context of different particle geometries.
In the past comparisons of experimentally and numerically obtained results demonstrated the adequacy of the discrete element method for predicting the general discharge behavior of a hopper. Nevertheless, in this study, comparing two different particle shape-approximations, significant differences in terms of bulk density, discharge rate, flow profile and dependency on the particle-wall friction coefficient between both investigated particle-shape approximation schemes could be observed. As a result, particle shape-representation must be considered a significant parameter in DEM-simulations.