Non-Oberbeck-Boussinesq effects and prediction of the bulk temperature in turbulent Rayleigh-Benard convection*

We report results of a complementary experimental and numerical study of turbulent non-Oberbeck-Boussinesq Rayleigh-Benard convection (NOB RBC) in pressurized sulfur hexafluoride (SF6). The measurements are conducted in a cylindrical cell of a height 2.2m and diameter 1.1m in the Uboot of the Max Planck Turbulence Facility in  Göttingen and direct numerical simulations (DNS) are performed with the Goldfish code, for a wide range of Rayleigh numbers and different NOB conditions. The numerical and experimental results are compared with predictions for the bulk and the reference temperatures of the top and bottom boundary layers made in Weiss, He, Ahlers, Bodenschatz, Shishkina, J. Fluid Mech., 2018.