Prandtl-Number Dependence of Heat Transport in Turbulent Rayleigh-Bénard Convection
2001; American Physical Society; Volume: 86; Issue: 15 Linguagem: Inglês
10.1103/physrevlett.86.3320
ISSN1092-0145
Autores Tópico(s)Phase Equilibria and Thermodynamics
ResumoWe present measurements of the Nusselt number $N$ as a function of the Rayleigh number $R$ and the Prandtl number $\ensuremath{\sigma}$ in cylindrical cells with aspect ratios $\ensuremath{\Gamma}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ and 1.0. We used acetone, methanol, ethanol, and 2-propanol with Prandtl numbers $\ensuremath{\sigma}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4.0$, 6.5, 14.2, and 34.1, respectively, in the range $3\ifmmode\times\else\texttimes\fi{}{10}^{7}\ensuremath{\lesssim}R\ensuremath{\lesssim}{10}^{11}$. At constant $R$, $N(R,\ensuremath{\sigma})$ varies with $\ensuremath{\sigma}$ by only about $2%$. This result disagrees with the extrapolation of the Grossmann and Lohse theory beyond its range of validity, which implies a decrease by $20%$ over our $\ensuremath{\sigma}$ range, but agrees with their recent extension of the theory to small Reynolds numbers.
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