Energy transfers during dynamo reversals

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Publication Details

Output type: Journal article

Author list: Mishra P, Gissinger C, Dormy E, Fauve S

Publisher: IOP Publishing

Publication year: 2013

Journal: European Physical Society Letters (0295-5075)

Volume number: 104

Issue number: 6

ISSN: 0295-5075

eISSN: 1286-4854

Languages: English-Great Britain (EN-GB)

Unpaywall Data

Open access status: green

Full text URL: https://arxiv.org/pdf/1309.5062

Abstract

Using direct numerical simulations of the equations of magnetohydrodynamics, we study reversals of the magnetic field generated by the flow of an electrically conducting fluid in a sphere. We show that at low magnetic Prandtl numbers, Pm = 0.5, the decrease of magnetic energy, ohmic dissipation and power of the Lorentz force during a reversal is followed by an increase of the power injected by the force driving the flow and an increase of viscous dissipation. Cross correlations show that the power of the Lorentz force is in advance with respect to the other energy flows. We also observe that during a reversal, the maximum of the magnetic energy density migrates from one hemisphere to the other and comes back to its initial position, in agreement with recent experimental observations. For larger magnetic Prandtl numbers (Pm - 1, 2), the magnetic field reversals do not display these trends and strongly differ one from another. Copyright (C) EPLA, 2013

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