Instability in Simulated Granular Chute Flows

Numerical simulations show that two-dimensional granular solids in an inclined chute can flow as a steady, uniform stream or as intermittent groups, or slugs. Slugs, or groupings of the flowing solids, were found to be enhanced with decreases in the coefficient of restitution of the granular particles and with decreases in the bulk number density or concentration of solids. A statistical parameter was developed to describe the degree of uniformity of the distribution of the granular particles along the chute. This parameter was found to have a predictable value at a well-defined transition point when the flow changed from a uniform to a sluglike behavior. An explanation is presented describing the significance of this parameter in terms of the mechanics of the flow process.