Large Eddy simulation of turbulent mixed convection in a 3D ventilated cavity: Comparison with existing data

We consider in this study the mixed convection airflow encountered in a 3D anisothermal cavity ventilated with supply and exhaust slots under stable thermal stratification. The flow in this cavity has been experimentally studied in the past (S. Mergui, Caractérisation expérimentale des écoulements d'air de convection naturelle et mixte dans une cavité fermée, thèse de l'Université de Poitiers, France, 1993) and was subject to a jet deflection and to a sudden change in the flow pattern between a general clockwise rotation and a counter-clockwise rotation when varying the inlet jet velocity. This phenomenon also exhibits a hysteresis effect depending on the way the velocity is changed, which made us to think that this flow bifurcation is of subcritical nature. Numerical studies have been yet devoted to this configuration, using RANS simulations or Large Eddy Simulation (LES), but this phenomenon has not been reported. So, we chose to numerically study this challenging flow with an LES approach associated with a subgrid diffusivity model previously developed for natural convection airflows. The comparison with the available experimental data and with other LES results using a classical dynamic model proves that the present LES not only correctly predicts the mean characteristics of the flow but is also able to correctly reproduce the flow bifurcation and the hysterisis effect.