Interface-resolved large eddy simulations of hyperconcentrated flows using spheres and gravel particles

Abstract

Interface-resolved large eddy simulations were performed to reproduce hyperconcentrated water-particle mixture flows in a laboratory experiment conducted by Egashira et al. (2001). The flows were simulated at sediment concentrations of 0.196 and 0.444 using spheres and gravel particles. Simulations using gravel with a suitable shape properly reproduced the discharge rates of water and particles as well as the wall-normal distributions of the particle velocities in the experiments. The study involved an examination of the effects of particle shapes and the coefficients of contact forces (coefficients of restitution and friction angles of particle surfaces) used in the discrete element method on mixture flows. Significantly different flows were obtained for spherical and gravel particles under dense conditions, whereby the particle shear stress became much greater than that for water. The simulations of spheres at different coefficients of contact forces could not adequately represent the mixture flows of nonspherical particles.