Direct simulation of particle dispersion in a three-dimensional temporal mixing layer

Abstract

A three–dimensional temporally evolving mixing layer and particle dispersion patterns with different Stokes numbers were investigated. The coherent structures in a plane mixing layer between two parallel streams were numerically simulated using a pseudo–spectral method. Particles with different Stokes numbers were traced using the Lagrangian approach. The results showed that particle dispersion patterns were strongly governed by large–scale vortex structures and three–dimensionality. Particles with Stokes number of the order of unity were found to be concentrated near the outer edges of the large–scale vortex structures. With the development of threedimensionality, the variation of particle distribution increased along the spanwise direction. Some particles were thrown out of the high–concentration area due to the pairs of counter–rotating ‘rib’ vortices, and finally developed into a ‘mushroom’ pattern of the particle distribution in the spanwise direction.