Asymmetries in Turbulent Rayleigh-Bénard Convection

Abstract

We report high-resolution local temperature measurements in the upper and the lower boundary layer of turbulent Rayleigh–Bénard (RB) convection. The measurements were undertaken in air (Pr = 0.71) at constant aspect ratio Γ= 1.13 and variable Rayleigh number 5×10⁵ < Ra < 10¹². The primary purpose of the work is to preserve a comprehensive data set of the temperature field against which various phenomenological theories and numerical simulations can be tested. In our talk we show the mean temperature profiles ϑ _h (z) at the heating and ϑ _c (z) at the cooling plate. We demonstrate, that the corresponding profiles do not collapse even at low Rayleigh numbers and that the measured bulk temperature ϑ _b strongly deviates from the mean between the heating and the cooling plate ϑ _b,t. Normalizing all temperatures to the difference between the plates, the deviation remains constant for all Ra > 2×10¹¹.