Application of Large Eddy Simulation models to Viscoelastic thermal convection turbulence

Viscoelastic thermal convection turbulence is an important branch of viscoelastic Rayleigh–Bérnard convection (VRBC). It is well established that the aspect ratio (AR) has a significant influence on turbulent RBC; however, its impact on turbulent VRBC remains poorly understood, particularly at large AR. In this study, large-eddy simulation (LES) based on the finite volume method (FVM) is employed to investigate turbulent VRBC over a range of aspect ratios. Three eddy-viscosity models are implemented and systematically evaluated against DNS results to assess their performance. Using the validated LES framework, turbulent VRBC at different aspect ratios is further investigated. The present results reveal a strong dependence on the Weissenberg number (Wi) at large aspect ratios. Specifically, Heat transfer enhancement(HTE) is observed at low elasticity (Wi< 1.0), whereas a transition to heat transfer reduction (HTR) occurs at higher elasticity (Wi> 1.0). HTE is closely associated with flow structure modulation: at low elasticity, the number of large-scale structures in the flow increases, which enhances the overall heat transfer efficiency. In contrast, HTR arises from elasticity-induced energy transfer from the mean flow to turbulent fluctuations, which weakens the mean circulation and consequently reduces the heat transfer efficiency.