Magnetic helicity transport in the advective gauge family

Candelaresi, S. , Hubbard, A., Brandenburg, A. and Mitra, D. (2011) Magnetic helicity transport in the advective gauge family. Physics of Plasmas, 18(1), 012903. (doi: 10.1063/1.3533656)

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Magnetic helicity fluxes are investigated in a family of gauges in which the contribution from ideal magnetohydrodynamics takes the form of a purely advective flux. Numerical simulations of magnetohydrodynamic turbulence in this advective gauge family exhibit instabilities triggered by the build-up of unphysical irrotational contributions to the magnetic vector potential. As a remedy, the vector potential is evolved in a numerically well behaved gauge, from which the advective vector potential is obtained by a gauge transformation. In the kinematic regime, the magnetic helicity density evolves similarly to a passive scalar when resistivity is small and turbulent mixing is mild, i.e., when the fluid Reynolds number is not too large. In the dynamical regime, resistive contributions to the magnetic helicity flux in the advective gauge are found to be significant owing to the development of small length scales in the irrotational part of the magnetic vector potential.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Candelaresi, Dr Simon
Authors: Candelaresi, S., Hubbard, A., Brandenburg, A., and Mitra, D.
College/School:College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Physics of Plasmas
Publisher:AIP Publishing
ISSN (Online):1089-7674
Published Online:10 January 2011

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