Transition on local temperature fluctuations in highly turbulent convection

• Published in: Europhysics letters Vol. 87; no. 4; p. 44006
• Main Authors: Gauthier, F, Salort, J, Bourgeois, O, Garden, J.-L, du Puits, R, Thess, A, Roche, P.-E
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2009; EDP Sciences; European Physical Society / EDP Sciences / Società Italiana di Fisica / IOP Publishing
• Subjects: 44.25.+f; 47.27.te; 47.80.-v; Condensed Matter; Engineering Sciences; Fluid mechanics; Fluids mechanics; Mechanics; Other; Physics
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/87/44006

In 1997, a new turbulent regime has been observed in a Rayleigh-Bénard cell and has been interpreted as the “Ultimate Regime” of convection. This observation was based on global heat transfer measurements at very high Rayleigh numbers (Ra). Using a set-up similar to the one used in 1997, we examine the signature of this regime from within the flow itself. A systematic study of probe-size corrections shows that the earlier local temperature measurements within the flow were altered by an excessive size of thermometer, but not according to a theoretical model proposed in the literature. Using a probe one order of magnitude smaller than the one used previously, we find evidence that the transition to the very-high-Ra regime is indeed accompanied with a clear change in the statistics of temperature fluctuations in the flow.