Persistent corotation of the large-scale flow of thermal convection and an immersed free body.

Proc Natl Acad Sci U S A

New York University-East China Normal University Institute of Physics, New York University Shanghai, Shanghai 200062, PR China.

Published: May 2023

Inspired by the superrotation of the Earth's solid core, we investigate the dynamics of a free-rotating body as it interacts with the large-scale circulation (LSC) of the Rayleigh-Bénard thermal convection in a cylindrical container. A surprising and persistent corotation of both the free body and the LSC emerges, breaking the axial symmetry of the system. The corotational speed increases monotonically with the intensity of thermal convection, measured by the Rayleigh number Ra, which is proportional to the temperature difference between the heated bottom and cooled top. The rotational direction occasionally and spontaneously reverses, occurring more frequently at higher Ra. The reversal events follow a Poisson process; it is feasible that flow fluctuations randomly interrupt and reestablish the rotation-sustaining mechanism. This corotation is powered by thermal convection alone and promoted by the addition of a free body, enriching the classical dynamical system.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10214213PMC
http://dx.doi.org/10.1073/pnas.2217705120DOI Listing

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