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arXiv · 2511.01582

Swaying oscillations in Rayleigh-B\'enard convection cast new light on solar convection

F. Kupka·D. Fabbian·F. Zaussinger·D. Krüger·L. Gizon
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Abstract

Horizontally-periodic Boussinesq Rayleigh-B\'enard Convection (RBC) is a simple model system to study the formation of large-scale structures in turbulent convective flows. We performed a suite of 2D numerical simulations of RBC between no-slip boundaries at different Prandtl (Pr) and Rayleigh (Ra) numbers, such that their product is representative of the Sun's upper convection zone. When the fluid viscosity is sufficiently low (Pr $\lesssim 0.1$) and turbulence is strong (Ra $> 10^6$) we find that large structures begin to couple in time and space. For Pr = 0.01 we observe long-lived swaying oscillations of the upflows and downflows, which synchronize over multiple convection cells. This new regime of oscillatory convection may offer an interpretation for the wave-like properties of the dominant scale of convection on the Sun (supergranulation).

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F. Kupka, D. Fabbian, F. Zaussinger, D. Krüger, L. Gizon. 2025-11-03. Swaying oscillations in Rayleigh-B\'enard convection cast new light on solar convection. https://doi.org/10.1051/0004-6361%2F202346508

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