Granular-Fluid Chute Flow: Experimental and Numerical Observations

Abstract

Equations of motion and boundary conditions for a flowing granular-fluid mixture, both based in the kinetic theory for granular flow, are here extended to allow for drag forces resulting from the interstitial fluid that cushions interparticle collisions and particle-wall collisions. Frictional stresses produced when long-term contacts are present and fluid turbulent fluctuations are introduced in the model. The results are compared with measurements from an experimental chute in which the inclination, the solids flow rate, and the fluid flow rate are all varied. The results show that for the same physical conditions (slope, channel roughness, and particle size) there is a value of concentration at which the ratio of collisional stresses over total stresses is a maximum. The theory is found to give a good qualitative account of the observed behavior.