Reynolds numbers near the ultimate state of turbulent Rayleigh-B\'enard convection etc15 Tracking Number 240Presentation: Session: Thermally driven turbulence 1 Room: Room M Session start: 10:30 Thu 27 Aug 2015 Guenter Ahlers guenter@physics.ucsb.edu Affifliation: UCSB Xiaozhou He xiaozhou.he@ds.mpg.de Affifliation: MPIDS G\"ottingen Dennis van Gils dennis.van-gils@ds.mpg.de Affifliation: MPIDS G\"ottingen Eberhard Bodenschatz eberhard.bodenschatz@ds.mpg.de Affifliation: MPIDS G\"ottingen Topics: - Thermally driven turbulence Abstract: We report on measurements of the mean-flow Reynolds number $Re_U$ and the rms fluctuation Reynolds number $Re_V$ in turbulent Rayleigh-B\'enard convection as a function of the Rayleigh number $Ra$ for $4\times 10^{11} \alt Ra \alt 2\times 10^{14}$ and $Pr \simeq 0.8$. Both can be described by the same power law with an effective exponent $\zeta = 0.44$, in agreement with predictions for $Re_U$ but in disagreement with predictions for $Re_V$. |