Effects of particle properties on the structure of clusters

Effects of physical properties of particles on the structure of particle clusters are studied numerically. The numerical simulations were 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. Flows of the solid phase are obtained by calculating individual particle motions, i.e. by the Lagrangian method, while gas flows are obtained by solving the equations of inviscid fluid. The Direct Simulation Monte Carlo (DSMC) method is used to take account of particle-to-particle collisions. The following results are obtained. The spatial structure of a cluster predicted 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 previous experiments. The size of cluster increases with increasing the particle size. The predicted range of cluster size agreed with the experiments by Horio and Kuroki (1994).