Simple Kinetic Model for Rapid Granular Flows Including Frictional Losses

A simple kinetic model for flows of nearly elastic granular materials in the grain‐inertia regime is presented, which includes the effects of frictional‐energy dissipation during collision. It is shown that frictional losses have the same effects as energy dissipation due to the inelasticity of granular particles. The special case of granular simple shear flow is treated in detail. Variations of stress components with solid volume fraction, coefficient of restitution, and friction coefficient are studied. The results are compared with the available experimental data for rapid shearing of glass and polystyrene beads and good agreement is observed. For small values of the coefficient of friction, it is shown that the shear and normal stresses decrease as frictional‐energy dissipation increases. The decrease in normal stress is more noticeable than that of the shear stress.