Numerical simulation of gas-particle flows behind a backward-facing step using an improved stochastic separated flow model

An improved stochastic separated flow (ISSF) model developed by the present authors is tested in gas-particle flows behind a backward-facing step, in this paper. The gas phase of air and the particle phase of 150 mum glass an d 70 mum copper spheres are numerically simulated using the k-epsilon model and the ISSF model, respectively. The predicted mean streamwise velocities as well as streamwise and transverse fluctuating velocities of both phases agree well with experimental data reported by Fessler. The reattachment le ngth of 7.6H matches well with the experimental value of 7.4H. Distribution s of particle number density are also given and found to be in good agreeme nt with the experiment. The sensitivity of the predicted results to the num ber of calculation particles is studied and the improved model is shown to require much less calculation particles and less computing time for obtaini ng reasonable results as compared with the traditional stochastic separated flow model. It is concluded that the ISSF model can be used successfully i n the prediction of backward-facing step gas-particle flows, which is chara cterised by having recirculating regions and anisotropic fluctuating veloci ties.