Reversals in infinite-Prandtl-number Rayleigh-Bénard convection

Abstract

Using direct numerical simulations, we study the statistical properties of reversals in two-dimensional Rayleigh-Bénard convection for infinite Prandtl number. We find that the large-scale circulation reverses irregularly, with the waiting time between two consecutive genuine reversals exhibiting a Poisson distribution on long time scales, while the interval between successive crossings on short time scales shows a power law distribution. We observe that the vertical velocities near the sidewall and at the center show different statistical properties. The velocity near the sidewall shows a longer autocorrelation and $1/f^2$ power spectrum for a wide range of frequencies, compared to shorter autocorrelation and a narrower scaling range for the velocity at the center. The probability distribution of the velocity near the sidewall is bimodal, indicating a reversing velocity field. We also find that the dominant Fourier modes capture the dynamics at the sidewall and at the center very well. Moreover, we show a signature of weak intermittency in the fluctuations of velocity near the sidewall by computing temporal structure functions.

arXiv comment12 pages, 17 figures

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Cited by in corpus (4)

• Thermal boundary layer structure in low-Prandtl-number turbulent convection
• Non-Boussinesq convection at low Prandtl numbers relevant to the Sun
• Similarities between characteristics of convective turbulence in confined and extended domains
• Lagrangian coherent sets in turbulent Rayleigh-Bénard convection