Field correlations and the ultimate regime of turbulent convection

Abstract

Using direct numerical simulations of Rayleigh-Bénard convection (RBC) under free-slip boundary condition, we show that the normalized correlation function between the vertical velocity field and the temperature field, as well as the normalized viscous dissipation rate, scales as $R{a}^{-0.22}$ for moderately large Rayleigh number $Ra$. This scaling accounts for the Nusselt number ($Nu$) exponent to be around 0.3 observed in experiments. Numerical simulations also reveal that the above normalized correlation functions are constants for the convection simulation under periodic boundary conditions.

4 pages, 4 figures

References in corpus (5)

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• "Ultimate state" of two-dimensional Rayleigh-Benard convection between free-slip fixed temperature boundaries
• Energy spectra and fluxes for Rayleigh-Benard convection
• Wind and boundary layers in Rayleigh-Benard convection. I: analysis and modeling
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