What is a large-scale dynamo?

Abstract

We consider kinematic dynamo action in a sheared helical flow at moderate to high values of the magnetic Reynolds number Rm. We find exponentially growing solutions which, for large enough shear, take the form of a coherent part embedded in incoherent fluctuations. We argue that at large Rm large-scale dynamo action should be identified by the presence of structures coherent in time, rather than those at large spatial scales. We further argue that although the growth-rate is determined by small-scale processes, the period of the coherent structures is set by mean-field considerations.

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Item Type:	Article
Authors/Creators:	Nigro, G Pongkitiwanichakul, P Cattaneo, F Tobias, SM
Copyright, Publisher and Additional Information:	(c) 2017, Oxford University Press . This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Nigro, G, Pongkitiwanichakul, P, Cattaneo, F et al. (1 more author) (2017) What is a large-scale dynamo? Monthly Notices of the Royal Astronomical Society, 464 (1). pp. 119-123 is available online at https://doi.org/10.1093/mnrasl/slw190
Keywords:	dynamo; magnetic fields
Dates:	Published: January 2017 Published (online): 23 September 2016 Accepted: 16 September 2016
Institution:	The University of Leeds
Academic Units:	The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds)
Depositing User:	Symplectic Publications
Date Deposited:	23 Sep 2016 09:20
Last Modified:	02 Jul 2017 05:53
Published Version:	https://doi.org/10.1093/mnrasl/slw190
Status:	Published
Publisher:	Oxford University Press
Identification Number:	10.1093/mnrasl/slw190
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:104788

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What is a large-scale dynamo?

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