COMPUTER-SIMULATION OF HOPPER FLOW

This paper describes two-dimensional computer simulations of granular flow in plane hoppers. The simulations can reproduce an experimentally observed asymmetric unsteadiness for monodispersed particle sizes, bu t also could eliminate it by adding a small amount of polydispersity, This appears to be a result of the strong packings thar may be formed by monodispersed particles and is thus a noncontinuum effect. The inte rnal stress stale tvas also sampled, which among other things, allows an evaluation of common assumptions made in granular material models, These showed that the internal friction coefficient is far from a cons tant, which is in contradiction to common models based on plasticity t heory which assume that the material is always al the point of imminen t yield. Furthermore, it is demonstrated that rapid granular flow theo ry, another common modeling technique, is inapplicable to this problem even near the exit where the flow is moving its fastest. (C) 1996 Ame rican Institute of Physics.