Inclined granular flow in a narrow chute.

In this paper we presents a detailed description of granular flow down a flat, narrow chute using discrete element method simulations, with emphasis on the influence of sidewalls on the flow. The overall phase diagram is provided and it is found that there are four flow regimes (no flow, bulk flow, surface flow, and gas flow). The H̃stop curve is very complicated and quite different from that in the case without sidewalls. The effective friction coefficient [Formula: see text] increases with pile height H̃ and a surface flow occurs when the inclination angle [Formula: see text] exceeds a critical value. The profile of [Formula: see text] shows that the [Formula: see text] rheology is valid in boundary layers. Furthermore, [Formula: see text] increases with the velocity of particles and there is a saturation to a nonzero value in static heap. For small H̃, the static heap vanishes and there is a bulk flow. A similarity between basal particles and sidewall particles indicates a universal role of the boundaries. In this bulk flow, there is a transition of the velocity profile with wall friction [Formula: see text]. When [Formula: see text] is large, the velocity is linear and decreases with increasing height. With small [Formula: see text], the velocity is nonlinear and the flow rate is roughly proportional to H̃3/2 .