Large eddy simulation of particle dispersion in a three-dimensional turbulent mixing layer

Particle dispersion in an unforced, three-dimensional, temporally evolving mixing layer has been studied using large eddy simulation (LES) of the incompressible Navier-Stokes equations. Subgrid-scale stresses were parameterized using the Lagrangian dynamic eddy viscosity model of Meneveau et al. (1994). The initial conditions for the mixing layer were obtained from calculations of fully developed turbulent channel flow; the momentum thickness Reynolds number ranged from 710 in the initial field to 4460 at the end of the calculation. Following a short development period, the layer evolves nearly self-similarly. Statistics of the fluid velocity are in good agreement with both the direct numerical simulation results of Rogers & Moser (1994) and experimental measurements of Bell & Mehta (1990). Particle statistics were obtained by following the trajectories of up to 50,000 particles. The particles used in the simulations have the same material properties as in the experiments of Hishida et al. (1992). In general, statistics of the particle cloud are in reasonable agreement with experimental measurements. Though perturbations are not superimposed on the layer to initiate development of coherent structures, visualizations reveal large-scale coherence in the particle number density field.