A subgrid lagrangian stochastic model for turbulent scalar dispersion.

AGUIRRE C. A., I. VINKOVIC AND S. SIMOËNS

Williamsburg, Virginia

Simposio; Fourth International Symposium on Turbulent and 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 passive scalar dispersion in a turbulent boundary layer. Instead of resolving the passive scalar transport equation, fluid particles containing scalar are tracked in a Lagrangian way. The Lagrangian velocity of each fluid particle is considered to have a large-scale part (directly computed by the LES) and a small-scale part. The movement of fluid elements containing scalar at a subgrid level is given by a three-dimensional Langevin model. The stochastic model is written in terms of SGS statistics at a mesh level. The results of the LES are compared with the wind-tunnel experiments of Fackrell and Robins (1982 J. Fluid Mech. 117 1-26) and with the LES results of Sykes and Henn (1992 Atmos. Environment 26A 3127-3144). Moreover, by using the Lagrangian approach, scalar fluxes are computed with no additional modeling assumptions and show good agreement with the experimental data.