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Simulationsdaten der Dissertation: "Numerische Untersuchung der Rayleigh-Bénard-Konvektion in einem Flüssigmetall unter dem Einfluss einer zeitlich modulierten gezeitenartigen Kraft"

We present results on the synchronization of the helicity in a liquid-metal Rayleigh-Bénard (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.

A possible explanation for the apparent phase stability of the 11.07-year Schwabe cycle of the solar dynamo was the subject of a series of recent papers [1, 2, 3]. The synchronization of the helicity of an instability with azimuthal wavenumber m=1 by a tidal m=2 perturbation played a key role here. To analyze this type of interaction in a paradigmatic set-up, we study a thermally driven Rayleigh-Bénard Convection (RBC) of a liquid metal under the influence of a tide-like electromagnetic forcing. As shown previously, the time-modulation of this forcing emerges as a peak frequency in the m=2 mode of the radial flow velocity component. In this paper we present new numerical results on the interplay between the Large Scale Circulation (LSC) of a RBC flow and the time modulated electromagnetic forcing.

Package of raw and refined data underlying the figures of the connected paper. Included is also the software used to generate the figures.

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A possible explanation for the apparent phase stability of the 11.07-year Schwabe cycle of the solar dynamo was the subject of a series of recent papers [1, 2, 3]. The synchronization of the helicity of an instability with azimuthal wavenumber m=1 by a tidal m=2 perturbation played a key role here. To analyze this type of interaction in a paradigmatic set-up, we study a thermally driven Rayleigh-Bénard Convection (RBC) of a liquid metal under the influence of a tide-like electromagnetic forcing. As shown previously, the time-modulation of this forcing emerges as a peak frequency in the m=2 mode of the radial flow velocity component. In this paper we present new numerical results on the interplay between the Large Scale Circulation (LSC) of a RBC flow and the time modulated electromagnetic forcing.

We show and compare 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 flows are 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. A similar entrainment mechanism for the helicity in the Sun may be responsible for the synchronization of the solar dynamo with the alignment cycle of the tidally dominant planets Venus, Earth and Jupiter.

The two 7z Archives contain experimental data and the corresponding evaluation software, as well as the code and setup of the numerical part of the paper "Generating a tide-like flow in a cylindrical vessel by electromagnetic forcing".

We present first results of our experiment involving electromagnetic forcing of a liquid metal volume. The experiment consist of a cylinder filled with eutectic GaInSn alloy and two magnetic coils placed on opposite sides of the cylinder. An alternating current in the coils excites Lorentz forces in the fluid, generating a flow field. Using ultrasound doppler velocimetry (UDV), we mapped this flow field. Maximum velocities of a few centimetres per second were reached. Numerical studies of the problem were also conducted and show good agreement. As a next step, the experimental setup shall be used to periodically disturb a Rayleigh-Bénard convection. The Rayleigh-Bénard flow structure occurs, when a layer of fluid is heated from below. The resulting flow is a convection roll about a horizontal axis. Point of interest is a possible resonance effect between the introduced forces and this flow structure.

We investigate the flow excited by electromagnetic forcing in a unit aspect ratio Rayleigh-Bénard cylinder. Flow structure and velocities dependent on AC frequency and coil current amplitude have been analysed. The unstable impinging jet flow bears interesting features, and a possible stochastic resonance is still under investigation.

To prepare an experiment on the potential resonance effect between the Rayleigh-Bénard convection and weak tidal forcing in a liquid metal, the influence of electromagnetic forcing on the eutectic metal Ga-In-Sn simulated in OpenFOAM will be the main topic of this work [1]. A modulated tidal m=2 Lorentz forcing will be produced by two opposing Helmholtz-like coils outside a Ga-In-Sn filled cylinder with an aspect ratio of one. Considering future analyses with additional Rayleigh-Bénard convection two Cu-plates installed at the bottom and the top of the volume are also taken into account for the simulation of the AC magnetic field. With a small magnetic flux density of a few mT a flow speed up to several centimeters per second can be produced. The results of the numerical simulations will be compared with experimental data.