A Proposal of Dynamic Random Walk SGS Model(Effect of Fluid SGS Component on Particle Motion in Large Eddy Simulation of Particle-Laden Turbulent Flows)

Abstract

In order to study the effect of turbulence sub-grid scale (SGS) component on particle motion, a new model named Dynamic Random Walk (DRW) SGS Coupling Model based on Eulerian-Lagrangian approach was presented. The advantage of the new model is that the Gaussian statistical distribution and local isotropic properties of turbulence SGS fluctuation magnitude could be parameterized by Germano's (1991) dynamic procedure. Using the present model, Large Eddy Simulation was performed for downward channel flow at Reynolds numbers of 180 that was identical to the DNS done by Rouson & Eaton in 1997. Through comparing of statistical properties of particles diffusion with DNS, the capability and limitation of presented DRW model was verified. Moreover, it was found that turbulence SGS component was strongly associated with particles motion because preferred particles were affected by preferred length scale of the eddy structure around, and fluid SGS component is indispensable in calculating particles motion with LES even though the particle Stokes number is high.