Large Eddy Simulation of Stably Stratified Turbulent Flow in a Wavy Wall Channel Grid dependency of SGS model and Mechanism of Turbulence Transport

摘要

Large eddy simulation (LES) was performed for flow and heat transfer under stable density stratification in a wavy wall channel. Low-Mach-number approximation was applied to treat the effects of density variation. Mixed-time-scale (MTS) model were used as subgrid scale (SGS) model. Compared were intensity of velocity fluctuation in four kinds of grid systems, the grid dependency of the SGS model was found to be larger under stable stratification than that under neutral stratification. Discussion was also given to the mechanism of turbulence transport, and stable stratification was suggested (1) to increase the energy transport between Reynolds normal stresses far from the wavy wall, and (2) to reduce the spatial transport of turbulence near the wall.