Les of Thermally Stratified Turbulent Channel Flow at Low Prandtl Number

Abstract

In this paper Large Eddy Simulation (LES) is carried out for turbulent channel flow to assess the role the Prandtl and Richardson number on the turbulent heat transport. Fully developed turbulent channel flow configuration is used in the present study with top and bottom walls kept at constant temperature of Th and Tc. The Reynolds number calculated on the basis of friction velocity and channel half width are kept as 180, the molecular Prandtl number is 0.1 and Richardson number are 0, 20, 40, 60, 120 and 240. Wall Adaptive Local Eddy viscosity (WALE) model is used for modelling sub-grid stress tensor and Dynamic thermal model is used for modelling sub-grid heat flux. Mean velocity and temperature statistics as well as its variance, turbulent heat flux, turbulent Prandtl number are carried out and the role of Prandtl and Richardson number are examined. Also the instantaneous flow structures and temperature contours are visualized in order to understand the inherent physics of of streaks and vortices.