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Wind reversals in turbulent Rayleigh-Benard convection

Francisco Fontenele Araujo·S. Grossmann·D. Lohse
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Abstract

The phenomenon of irregular cessation and subsequent reversal of the large-scale circulation in turbulent Rayleigh-Bénard convection is theoretically analysed. The force and thermal balance on a single plume detached from the thermal boundary layer yields a set of coupled nonlinear equations, whose dynamics is related to the Lorenz equations. For Prandtl and Rayleigh numbers in the range $10^{-2} \leq \Pr \leq 10^{3}$ and $10^{7} \leq \Ra \leq 10^{12}$, the model has the following features: (i) chaotic reversals may be exhibited at Ra $\geq 10^{7}$; (ii) the Reynolds number based on the root mean square velocity scales as $\Re_{rms} \sim \Ra^{[0.41 ... 0.47]}$ (depending on Pr), and as $\Re_{rms} \sim \Pr^{-[0.66 ... 0.76]}$ (depending on Ra); and (iii) the mean reversal frequency follows an effective scaling law $ω/ (νL^{-2}) \sim \Pr^{-(0.64 \pm 0.01)} \Ra^{0.44 \pm 0.01}$. The phase diagram of the model is sketched, and the observed transitions are discussed.

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Francisco Fontenele Araujo, S. Grossmann, D. Lohse. 2005-08-29. Wind reversals in turbulent Rayleigh-Benard convection. https://doi.org/10.1103/physrevlett.95.084502

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