We show and compare the numerical and experimental results on the electromagnetic generation of a tide-like flow structure in a cylindrical vessel, which is filled with the eutectic liquid metal alloy GaInSn. Fields of various strengths and frequencies are applied to drive liquid metal flows. The impact of the field variations on amplitude and structure of the flow is investigated. The results represent the basis for a future Rayleigh–Bénard experiment, in which a modulated tide-like flow perturbation is expected to synchronize the typical sloshing mode of the large-scale circulation and the helicity oscillation connected with it. A similar entrainment mechanism might play a role in the synchronization of stellar dynamos by tidal forces.

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.

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