Heat Transfer in Turbulent Rayleigh-Bénard Convection below the Ultimate Regime

Content Provider	Semantic Scholar
Author	Roche, P. A.
Copyright Year	2003
Abstract	A Rayleigh-Bénard cell has been designed to explore the Prandtl (Pr) dependence of turbulent convection in the cross-over range 0.7 < Pr < 21 and for the full range of soft and hard turbulences, up to Rayleigh number Ra ≃ 10. The set-up benefits from the favourable characteristics of cryogenic helium-4 in fluid mechanics, in-situ fluid property measurements, and special care on thermometry and calorimetric instrumentation. The cell is cylindrical with diameter/height = 0.5. The effective heat transfer Nu(Ra, Pr) has been measured with unprecedented accuracy for cryogenic turbulent convection experiments in this range of Rayleigh numbers. Spin-off of this study include improved fits of helium thermodynamics and viscosity properties. Three main results were found. First the Nu(Ra) dependence exhibits a bimodality of the flow with 4 − 7% difference in Nu for given Ra and Pr. Second, a systematic study of the side-wall influence reveals a measurable effect on the heat transfer. Third, the Nu(Pr) dependence is very small or null : the absolute value of the average logarithmic slope (dlnNu/dlnPr)Ra is smaller than 0.03 in our range of Pr, which allows to disciminate between contradictory experiments [Ashkenazi et al., Phys. Rev.Lett. 83:3641 (1999)][Ahlers et al., Phys.Rev.Lett. 86:3320 (2001)].
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://arxiv.org/pdf/cond-mat/0307518v1.pdf
Alternate Webpage(s)	https://hal.archives-ouvertes.fr/hal-00000512/document
Alternate Webpage(s)	http://arxiv.org/pdf/cond-mat/0307518v2.pdf
Alternate Webpage(s)	http://arxiv.org/pdf/cond-mat/0307518v3.pdf
Language	English
Access Restriction	Open
Subject Keyword	Convection Diameter (qualifier value) Exhibits as Topic Experiment FITS Helium Instrument - device Mechanics Null Value REV Rayleigh–Ritz method Small Thermometry Turbulence benefit
Content Type	Text
Resource Type	Article