Simulation of particle dispersion in an axisymmetric jet

Abstract

Particle dispersion in an axisymmetric jet is analysed numerically by following particle trajectories in a jet flow simulated by discrete vortex rings. Important global and local flow quantities reported in experimental measurements are successfully simulated by this method.The particle dispersion results demonstrate that the extent of particle dispersion depends strongly on γ_τ, the ratio of particle aerodynamic response time to the characteristic time of the jet flow. Particles with relatively small γ_τ values are dispersed at approximately the fluid dispersion rate. Particles with large γ_τ values are dispersed less than the fluid. Particles at intermediate values of γ_τ may be dispersed faster than the fluid and actually be flung outside the fluid mixing region of the jet. This result is in agreement with some previous experimental observations. As a consequence of this analysis, it is suggested that there exists a specific range of intermediate γ_τ at which optimal dispersion of particles in the turbulent mixing layer of a free jet may be achieved.