Synchronizing the helicity of Rayleigh–Bénard convection by a tide-like electromagnetic forcing

Abstract

We present results on the synchronization of the helicity in a liquid-metal Rayleigh–Bénard experiment under the influence of a tide-like electromagnetic forcing with azimuthal wavenumber m = 2. We show that for a critical forcing strength the typical large-scale circulation in the cylindrical vessel of aspect ratio unity is entrained by the period of the tide-like forcing, leading to synchronized helicity oscillations with opposite signs in two half-spaces. The obtained experimental results are consistent with and supported by numerical simulations. A similar entrainment mechanism for the helicity in the solar tachocline may be responsible for the astonishing synchronization of the solar dynamo by the 11.07-year triple synodic alignment cycle of the tidally dominant planets Venus, Earth, and Jupiter.

A Synchronized Two-Dimensional $\alpha $–$\Omega $ Model of the Solar Dynamo

“…magneto–Rossby), and on the -effect connected with them, has to be quantified in a reliable manner. Complementary work on tidal influences on Rayleigh–Bénard convection, and its large-scale circulation (Stepanov and Stefani, 2019 ; Jüstel et al., 2020 , 2022 ), might be helpful to elucidate helicity entrainment in a more generic sense.…”

Rieger, Schwabe, Suess-de Vries: The Sunny Beats of Resonance

“…A key observation of Stefani et al (2016) was then that those helicity oscillations of the TI (with its azimuthal wave number m = 1) are sensitive to entrainment by tide-like (m = 2) perturbations. For the not dissimilar case of an m = 1 Large Scale Circulation in a Rayleigh-Bénard convection problem, this concept of helicity synchronization by tide-like forcing was recently exemplified in a liquid metal experiment (Jüstel et al, 2020(Jüstel et al, , 2022.…”