Hydrodynamic effects of convective transport and mixing of dispersed reagents determine the efficiency of chemical reactions in some cases. The paper sets and numerically solves the problem of a pulsed outflow and mixing of gas suspension in a volume limited by walls. The initial dispersed-phase concentration at which an anomalous subsonic regime (with the shock-wave structure formation) is replaced by supersonic one (as to the velocity of the carrier gas phase) has been found. It was established that phenomena of instability development and eddying dominate for a long-time interval. The resolution of the hybrid large-particles method was demonstrated for this class of problems.