Boundary Conditions for Planar Granular Flows

Abstract

Boundary conditions are formulated for planar, smooth, rapidly sheared granular flows. The formulation allows the slip at the wall to be large compared to the local mean particle fluctuation speed. In previous work by Jenkins and Richman, slip was assumed small. In order to allow for large slip and obtain tractable results, a simple approximation to the particle velocity distribution is employed in the formulation for the traction forces and energy dissipation rate at the wall. The theory is applied to the Couette flow of granular material and shown to compare well to numerical simulations, and to Jenkins and Richman in the limit of small slip.