Direct numerical simulations of turbulent convection and thermal radiation in a Rayleigh-Bénard cell with solid plates

Abstract

In the present study the effect of the surface to surface radiation on the turbulent convection of air (Prandtl number Pr = 0.7) in a rectangular Rayleigh-Bénard cell is analysed by means of direct numerical simulations. In order to investigate the influence of the radiative boundary conditions on the temperature distribution, heat transfer and the flow intensity, a horizontal, poorly conducting walls with finite thickness are employed. Additionally, the influence of the radiative parameters is shown for Rayleigh number Ra = 6.3×10^7. We notice that the temperature at the warm interface decreases and it increases at the cold interface. Thus, the lower temperature difference appears what reduces the flow intensity. We observe that radiation causes a drop of convective heat flux however, the overall heat transfer increases due to high radiative heat flux. All the effects of radiation are stronger for higher conduction-radiation numbers and for higher temperature ratios.