Synchronizing the helicity of Rayleigh-B\'enard convection by a tide-like electromagnetic forcing

TL;DR

This study demonstrates how tide-like electromagnetic forcing can synchronize helicity oscillations in a liquid-metal Rayleigh-Bénard convection experiment, with implications for understanding solar dynamo synchronization.

Contribution

It introduces a novel electromagnetic forcing method to synchronize helicity in Rayleigh-Bénard convection and links this mechanism to solar dynamo phenomena.

Findings

Helicity oscillations synchronize with electromagnetic forcing at a critical strength.

Experimental results align with numerical simulations.

Potential link to solar dynamo synchronization by planetary tides.

Abstract

We present results on the synchronization of the helicity in a liquid-metal Rayleigh-B\'enard (RB) 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 (LSC) 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.