Large-Eddy Simulation of Particle-Laden Turbulent Flows over a Backward-Facing Step Considering Two-Phase Two-Way Coupling

Abstract

Particle-laden turbulent flows over a backward-facing step were here numerically studied by means of a large-eddy simulation considering two-way coupling between particle and fluid phases. The modification of turbulence by particles was then analyzed based on the predicted results of mean and fluctuating velocities. The influencing factors of particle size and material density were also evaluated. Turbulence modifications are anisotropic and closely dependent on flow status. Stronger modulations were observed in the up-wall shear flow regions. Fluid laden with smaller size, low-density particles showed enhancement of turbulence in the streamwise direction, but this effect was less pronounced in the case of larger low-density particles. Particle dispersions were also investigated for comparison of particle instantaneous distributions in coherent structures. Particle modulations of turbulence were not found to change particle preferential distributions. The conclusions drawn in the present study were useful for further understanding of a two-phase turbulence physical mechanism and establishment of accurate prediction models for engineering applications.