Particle-Dynamics Calculations of Gravity Flow of Inelastic, Frictional Spheres

摘要

Three-dimensional discrete-particle computer models that calculate the motion of each individual grain in assemblies of hundreds of particles in steady shearing flows with either periodic or real boundaries have been modified to simulate gravity flow of particles through arrays of cylindrical horizontal rods and down inclined chutes. The particle interaction models reproduce experimentally measured recoil trajectories for colliding frictional particles, including rotation effects. Laboratory measurements of the flow of glass beads cascading down through an array of horizontal cylindrical rods correlate well with gravity flow calculations of inelastic, frictional spheres falling through a similar rod array. Less elastic particles are found to cascade through the array faster than nearly elastic particles. Likewise, smaller particles are found to flow faster than large ones. Model simulations of nearly two-dimensional inclined chute flow tests of 6mm diameter cellulose-acetate spheres flowing over a rough surface between parallel vertical glass plates, result in particle velocities that are considerably higher than values measured in similar laboratory tests at UCLA; however, inclusion of approximate air drag effects in the calculational model eliminates most of the discrepancy producing both density and velocity profiles that are close to the measured values. 15 refs., 5 figs. (ERA citation 13:020001)