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12:00
15 mins
Reynolds numbers near the ultimate state of turbulent Rayleigh-B\'enard convection
Guenter Ahlers, Xiaozhou He, Dennis van Gils, Eberhard Bodenschatz
Session: Thermally driven turbulence 1
Session starts: Thursday 27 August, 10:30
Presentation starts: 12:00
Room: Room I

Guenter Ahlers (UCSB)
Xiaozhou He (MPIDS G\"ottingen)
Dennis van Gils (MPIDS G\"ottingen)
Eberhard Bodenschatz (MPIDS G\"ottingen)

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 $Re_V$.