Numerical simulation of dilute turbulent gas-solid flows

A new dilute turbulent gas-solid two-phase flow model in the grain inertia flow regime is developed in the present study. A set of time-averaged conservation equations for mass and momentum, and a two-equation multiscale k-omega closure are derived. The solid phase is composed of inelastic, frictional. uniform spheres. Each Lagrangian solid particle is tracked by integrating the particle equations of translational and rotational motion. The couplings in volume fraction, momentum and kinetic energy between the fluid and the solid phases are incorporated in this model. Turbulence modulation due to the solid particles is formulated on the basis of experimental observations. Interparticle collisions and particle-wall collisions are emulated by using a sticking-sliding collision model. The two-phase model is applied to study the steady state flow in a vertical pipe. Depending upon the particle size, mass loading and bulk carrier-fluid velocity, the two-phase system can experience turbulence attenuation, or augmentation, or a combination of both. In general, good agreement is found between the simulation prediction and the experimental data for the mean fluid and solid velocities. Furthermore, there is reasonable qualitative agreement for the fluid turbulence kinetic energy between the two. Many interesting numerical results for macroscopic flow properties of both fluid and solid phases are reported in this paper. (C) 2000 Elsevier Science Ltd. All rights reserved.