Effect of Particle Existence on Low Reynolds Number Gas-Particle Free Jet(Re=800)

Abstract

The rapid increase of available computational strage and speed has enabled the direct numerical simulation of the gas-particle jet, the Reynolds number of which is about one thousand, based on the Navier-Stokes equation and the Lagrangian equation of particle motion. In this study three-dimensional Eulerian air velocities and Largrangian particle trajectories are directly simulated to describe the effect of particle existence on the low Re number gas-particle free-jet flow using a two-way method. The results show that the small disturbances due to particle existence in the low Re number gas-particle free jet grow, and develop the flow to the turbulence. This is in fairly good agreement with the results obtained from the experimental flow patterns of low Re number free jets. The calculated flow characteristics of air and particles (mean velocity distributions and fluctuating intensity distributions) are also in fairly good agreement with experimental data obtained using a laser Doppler velocimeter. This means that the existence of particles enhances and develops unstable states in unstable laminar flows, such as low Re number free jets, to turbulence. The turbulence growth mechanism and the effects that the appearance of many small-scale eddies due to the particle existence has on the large-scales and vice versa have been discussed.