Numerical simulation of dilute turbulent gas-solid flows in horizontal channels

Abstract

A dilute turbulent gas-solid two-phase flow model is developed in the present study. Time-averaged conservation equations for mass and momentum, and a two-equation k− ϵ closure are used to model the fluid phase. The solid phase consisting of inelastic, frictional, uniform spheres is simulated by using a Lagrangian approach in which the particle trajectories and velocities are determined by integrating the particle equations of motion. The fluid-solid coupling effects due to solid volume fraction and interfacial momentum interaction are incorporated in the simulation. A sticking-sliding collision model is employed for the particle-particle collisions and the particle-wall collisions. The two-phase model is implemented to simulate gas-solid suspensions in a horizontal channel. Substantial agreement is found between the simulation result and the experimental data for the fluid pressure gradient, the distributions of mean gas velocity, mean particle velocity and concentration. For dilute systems with solids volume fraction of the order 10 −3, interparticle collisions are found to be crucial in sustaining a steady and fully developed suspension in the horizontal channel, while the Magnus lift due to particle rotation is found to play a significant role as well. Detailed new numerical results for macroscopic properties such as Reynolds stresses, air turbulence intensities, particle fluctuation kinetic energy, mean particle angular velocity, particle stresses and angular momentum fluxes are presented in the paper.