Abstract: We present a numerical investigation on the two-dimensional, dilute gas-particle two-phase flows passing a circular cylinder at high Reynoldes number. Here we apply the Discrete Vortex Method (DVM) to compute the unsteady and unstable gas flows, and adopt a Lagrangian approach to simulate the particle motion in flows. We numerically demonstrate that the definite interrelated structure exists between the particle motion and the vortices in gas-particle two-phase flows: Very large size particles (St>>1) are less affected by the vortices, of which motion is mainly determined by the initial velocity, thus follow nearly straightline trajectories. However, very small size particles (St<<1) follow the streamlines, have not impact with the blunts. (2) The motion of intermediate size particles (St~O (1.0), such as St=0.3) is obviously influenced by the vortices. When gas passes a circular cylinder at high Reynoldes number, unstable flow with massive separation is formed, the complicated motion of vortices exists in the wake region. Intermediate size particles are separated from the gas-particle mixture, then move toward the wake vortex region, finally concentrate near the outer edges of the vortex structures.

Key words: unsteady and unstable, gas-particle two-phase flow, vortex, particle motion, interrelated structure