Subgrid scale modelling of relaminarization effects in a differentially heated channel

Abstract

Turbulent mixed convection in a differentially heated vertical channel is simulated by means of direct numerical simulation and large eddy simulation. With regard to the LES different subgrid-scale models are compared and their ability to predict the flow is analysed. The comparison is based on statistical moments as well as two-point correlations that show the models’ abilities to represent the sizes of flow structures. A newly proposed local formulation for the classical Smagorinsky SGS model has been identified as the best choice for mixed convection flows, although it can still be improved. The importance of the accuracy of SGS heat flux models is shown to be negligible when the momentum transport is not predicted properly. Their influence can even lead to deviations in both momentum and heat transport as shown with the classical dynamic Smagorinsky model in combination with different SGS heat flux models.