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Evolution of convective rolls to zonal flows in horizontally rotating Rayleigh–Bénard convection.

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Title: Evolution of convective rolls to zonal flows in horizontally rotating Rayleigh–Bénard convection.
Authors: Mishra, Siddhant1 (AUTHOR), Pal, Anikesh1 (AUTHOR) pala@iitk.ac.in
Source: Journal of Fluid Mechanics. 5/10/2026, Vol. 1034, p1-29. 29p.
Subjects: Rayleigh-Bénard convection, Rotating fluid, Large eddy simulation models, Gas giants, Jet streams, Kinetic energy, Energy transfer
Abstract: Zonal winds on Jovian planets play an important role in governing the cloud dynamics, transport of momentum, scalars and weather patterns. Therefore, it is crucial to understand the evolution of zonal flows and their sustainability. Based on studies in two-dimensional $\beta$ -plane set-ups, zonal flow is believed to be forced at the intermediate scale via baroclinic instabilities, and the inverse cascade leads to the transfer of energy to large scales. However, whether such a process exists in three-dimensional deep convection systems remains an open and challenging question. To explore a possible answer, we perform large-eddy simulations at Rayleigh and Ekman numbers in the spans $10^7 {-} 10^{12}$ and $10^{-3}{-}10^{-8}$ , respectively, corresponding to the inverse of the convective Rossby number, $1/Ro_c$ , ranging from $0.1685$ to $168.52$ , in a horizontally rotating Rayleigh–Bénard convection set-up. We find the emergence of mean flow at the expense of small-scale turbulence for $1/Ro_c = 1.68522$ , $16.852$ and $168.52$. The turbulent kinetic energy budget analysis shows negative turbulent production in zonal flows, implying an energy transfer from the fluctuating velocity fields to the mean flow. We further quantify this energy transfer in spectral space using the kinetic energy spectra and the energy flux, and conclude that the energy deposited at small scales owing to the work done by buoyancy is transferred to large scales via upscale energy transfer, thus corroborating the emanation of a strong mean flow from chaos. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Zonal winds on Jovian planets play an important role in governing the cloud dynamics, transport of momentum, scalars and weather patterns. Therefore, it is crucial to understand the evolution of zonal flows and their sustainability. Based on studies in two-dimensional $\beta$ -plane set-ups, zonal flow is believed to be forced at the intermediate scale via baroclinic instabilities, and the inverse cascade leads to the transfer of energy to large scales. However, whether such a process exists in three-dimensional deep convection systems remains an open and challenging question. To explore a possible answer, we perform large-eddy simulations at Rayleigh and Ekman numbers in the spans $10^7 {-} 10^{12}$ and $10^{-3}{-}10^{-8}$ , respectively, corresponding to the inverse of the convective Rossby number, $1/Ro_c$ , ranging from $0.1685$ to $168.52$ , in a horizontally rotating Rayleigh–Bénard convection set-up. We find the emergence of mean flow at the expense of small-scale turbulence for $1/Ro_c = 1.68522$ , $16.852$ and $168.52$. The turbulent kinetic energy budget analysis shows negative turbulent production in zonal flows, implying an energy transfer from the fluctuating velocity fields to the mean flow. We further quantify this energy transfer in spectral space using the kinetic energy spectra and the energy flux, and conclude that the energy deposited at small scales owing to the work done by buoyancy is transferred to large scales via upscale energy transfer, thus corroborating the emanation of a strong mean flow from chaos. [ABSTRACT FROM AUTHOR]
ISSN:00221120
DOI:10.1017/jfm.2026.11479