Rheology of sheared polyhedral granular materials in inclined flows

Abstract

An investigation of frictional, Platonic solid-shaped particle flows on inclined planes is performed using the discrete element method, and the effects of particle angular shape on rheological properties are analyzed. Higher shear stresses at a specified depth of particle bed are obtained for more angular particles. As particle angularity increases, rapid surges in the coordination number and solid-phase stresses occur at a smaller critical solid volume fraction. The friction and dilatancy laws of polyhedral particle flows are significantly different from those of spherical particle flows, due to particle angularity. Nevertheless, by applying a specific rolling friction to the spherical particles, their rheological properties can match those of the polyhedral particles, indicating that the angular particle shape plays a similar role to the rolling friction in preventing particle rotation. Thus, the flows of spherical particles with a rolling friction incorporated can be used to mimic the flows of angular polyhedral particles. At last, a scaling law is adopted to describe rheological relations for various polyhedral particles based on a bulk friction coefficient, a dimensionless granular temperature, and an inertial number.