Numerical Simulation Of Cluster Formation in Gas-Solid Flow. Effects of Particle Size and Particle Concentration on the Structure of Clusters.

Effects of physical properties of particles on the structure of particle clusters are studied numerically. A numerical simulation was made on two-dimensional upward gas-solid flows in a rectangular domain with periodic boundaries. Flow fields of gas and solid are solved simultaneously taking the interaction between both phases into consideration. The flow of the solid phase is obtained by calculating individual particle motions, i. e. by the Lagrangian method, while gas flow is obtained by solving the equations of an inviscid fluid. The direct simulation Monte Carlo (DSMC) method is used to take account of particle-to-particle collisions, and the following results are obtained. The predicted spatial structure of particle clusters is like a strand. There are two typical types of clusters, a V-shaped cluster and an inverse V-shaped one. These patterns are consistent with those obtained from previous experiments. The cluster size increases with increasing particle size. The predicted range of cluster size agreed with that obtained from the experiments of Horio and Kuroki. Furthermore autocorrelations of the concentration distribution are discussed.