Kinetic grain flow in a vertical channel

A self-consistent kinetic grain flow model proposed earlier has been applied in detail to the description of rapid flow in a verticad channel. The equations of motion reduce to an ordinary differential equation for the fluctuation velocity ν, which is solved numerically. Boundary conditions on ν are derived which incorporate the nature of grain-wall collisions. The overall flow pattern is found to depend significantly upon the grain inelasticity parameter γ (γ = 0 for elastic grains) and upon the grain diameter d. The flow velocity profile is rounded for very elastic grains and for large grains, but becomes more blunt as grain diameter decreases or γ increases. For large enough γ, a region of plug flow develops in the central region of the channel, corresponding to a vanishing grain fluctuation velocity. In this case the region of dispersed or "thermalized" grains, within which all shearing occurs, is restricted to a thin layer near each wall. © 1986.

Duke Scholars

Author Peter K. Haff Earth and Climate Sciences