Large-eddy simulation of the dispersion of solid particles in a turbulent boundary layers

VINKOVIC I., M. AYRAULT, S. SIMOËNS AND C. AGUIRRE

Williamsburg, Virginia

Simposio; Fourth International Symposium on Turbulent Shear Flow Phenomena; 2005

Marriott Conference Center

A large eddy simulation (LES) with the dynamic Smagorinsky-Germano subgrid-scale (SGS) model is used to study the dispersion of solid particles in a turbulent boundary layer. Solid particles are tracked in a Lagrangian way. The resolution of the Lagrangian equation of the solid particle motion requires the knowledge of the instantaneous velocity of he surrounding fluid. This velocity is considered to have a large-scale part (directly computed by the LES) and a small-scale part. The subgrid-scale velocity of the surrounding fluid is given by a three-dimensional Langevin model. The stochastic model is written in terms of SGS statistics at a mesh level. In addition to this, an appropriate Lagrangian correlation timescale is considered in order to include the influences of gravity and inertia of the solid particle. The results of the LES are compared with the wind-tunnel experiments of Nalpanis et al. (1993 J. Fluid Mech. 251 661-685) and of Taniere et al. (1997 Exp. In Fluids 23 463-471) on sand particles in saltation and in modified saltation, respectively, over a flat bed. Our simulation predict the quantitative features of both experiments