A study of shape non-uniformity and poly-dispersity in hopper discharge of spherical and polyhedral particle systems using the Blaze-DEM GPU code

The importance of shape non-uniformity and the polydispersed nature of granular media in industrial hopper discharge applications has been well established experimentally. Although numerous hopper discharge simulations have been conducted over the last thirty years, the investigations into the non-uniformity of particle shape and the polydisperse nature of particle systems remains limited. These studies are usually limited to a single hopper configuration, while the number of polyhedral particles considered are usually limited to a maximum of 5000 particles. In this study we consider the polydispersed particle systems for hoppers at various angles, particle systems with non-uniform shape for hoppers at various angles and polyhedral particle systems up to 1 million particles. This is made possible by extensively utilizing the graphical processing unit (GPU) computing platform via the BlazeDEM3D-GPU code. We first perform an experimental validation of the code for mono-sized spherical and convex polyhedral shaped particles for lab-scale hoppers at three half angles using 3D printed polylactic acid material (PLA) particles. We found good agreement between the experimental, Meyrs and Sellers empirical relation and simulation discrete element method (DEM) discharge rates. We then simulate three larger square hoppers with varying half-angles to study the effect polydispersity and non-uniformity of particle shape have on the mass discharge rate. Again, good agreement between the DEM simulated mono-dispersed spherical particle systems and the Meyrs and Sellers empirical relation is obtained to verify the simulations. Finally we simulate an industrial sized silo for which we compare mono-dispersed spheres against mono-dispersed polyhedra using over a million polyhedral shaped particles. Finally, we briefly comment on the effect that the polydisperse nature of particle systems has on the loading of the supporting structure.