Simulations and physical measurements of glass spheres flowing down a bumpy incline

An inclined chute facility and its associated diagnostics has been develope d and utilized to study the flow of granular materials. A variety of flow r egimes and flow phenomena were observed. Fully developed flows were observe d over a bumpy base for a range of slopes. Under some conditions, these flo ws were dominated by friction and under other conditions, collisions played a dominant role. A variety of unsteady flows were also observed. These inc lude decelerating flows, accelerating flows, and wavy (periodic) flows. The characteristics of the base strongly influenced the flow regime and flow d ynamics. Discrete particle simulation model parameters were determined from individual particle tests and particle impact experiments. Simulations of nominally steady flows at two fixed angles showed relatively good agreement with experimental values for particle velocities near the side-walls and o n the top surface. The mass flow rate and the flow depth were also consiste nt with the experiments; however, both experiments and simulations exhibite d significant fluctuations about the nominal mean values. The simulations w ere utilized to interpret flow parameters interior to the flow (i.e., in re gions that cannot easily be measured non-intrusively). Far from the side-wa lls, the granular temperature was found to have a maximum near the bumpy ba se and to decrease toward the top surface - consistent with granular kineti c theory predictions for flows on bumpy inclines, without side-walls. Near the side-walls the behavior was substantially different with granular tempe rature decreasing from the top to a minimum at the lower 'corners' of the c hute. This behavior is consistent with experimental measurements of fluctua tion velocities near the side-walls. The simulations confirm that the previ ous discrepancy in the variation of the granular temperature with depth bet ween kinetic theory and near-side-wall measurements was a result of the sid e-walls, which cause strong three-dimensional structure in the flow. (C) 20 00 Elsevier Science S.A. All rights reserved.