LES OF DIFFUSION OF CONTAMINANT EMITTED IN ATMOSPHERIC BOUNDARY LAYER

Abstract

The concentration field of passive contaminant in a turbulent boundary layer with and without temperature stratification has been computed by large-eddy simulation (LES) method. With application to atmospheric flow over topography in mind, the numerical method has been constructed in curvilinear coordinates and the inflow boundary layer was generated by recycling velocity and temperature fluctuations in a driver section placed upstream of main calculation region. Different combinations of sub-grid scale (SGS) models for the momentum transfer and the heat and passive scalar fluxes were examined. The quality of prediction of the diffusion of passive scalar depends on the accuracy of turbulent fluctuations. The mixed time scale model combined with the dynamic eddy diffusion model was found to give the best results.