Application of DSMC method to study the impact diffusion characteristics of smoke particles

In order to study the dispersion characteristics of smoke particles in the process of smokescreen by pneumatic spray, a discrete particle motion-collision decoupled model was developed on the basis of particle collision dynamics to describe the formation process of smokescreen. The Direct Simulation Monte Carlo (DSMC) method was used to simulate the collision of smoke particles with the gasphase flow field, smoke particle velocity field and concentration distribution carefully examined. It is shown that the method decently simulate the particle motion and collision. The smokescreen jet flow divagates the initial direction, formes upward field with the velocity that reduced to 65%~75% original after collision, and spreades outward gradually with the shape approximately like a spherical cone. The smoke concentration reaches the maximum value in the jet and collision zone, while the collision effect of smoke particle gradually weakened outside of this area, so the smoke concentration gradient increases with height decreases rapidly because of the random diffusion effect, and the spatial distribution of smoke particles become more uniform.