LES of the turbulent coherent structures and particle dispersion in the gas–solid wake flows

Abstract

To deeply understand the particle dispersion and examine the reliability of large eddy simulation (LES) method in two-dimensional gas–solid free shear flows, a particle-laden plane wake flow was numerically investigated. The gas-phase field was solved by using large eddy simulation method, and the particle trajectories were traced in Lagrangian framework based on one-way coupling. The coherent structures and particle dispersion were simulated and compared with previous experiment results. The typical coherent structures alternately forming from the near-wall region, shedding and moving towards the downstream positions were observed. Due to the effects of the coherent structures, the particles demonstrate a more organized dispersion process in the space and a periodic dispersion characteristic in the time. However, for particles at different Stokes numbers, the dispersion patterns are different. Although the particles at smaller Stokes number congregate mainly in the vortex core regions and the particles at larger Stokes number assemble in the vortex braid regions, the particles at intermediate Stokes numbers concentrate highly in the boundary regions of the coherent structures. The two-phase flow characteristics obtained by the present large eddy simulation are in quantitative agreement with previous experiment results.