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Magnetic field intermittency and fast dynamo action in random helical flows

Published online by Cambridge University Press:  26 April 2006

Andrew D. Gilbert  and
B. J. Bayly
Andrew D. Gilbert
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver St., Cambridge CB3 9EW, UK
B. J. Bayly
Affiliation:
Mathematics Department, University of Arizona, Tucson, AZ 85721, USA
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Abstract

The evolution of passive magnetic fields is considered in random flows made up of single helical waves. In the absence of molecular diffusion the growth rates of all moments of a magnetic field are calculated analytically, and it is found that the field becomes increasingly intermittent with time. The evolution of normal modes of the ensemble-averaged field is determined; it is shown that the flows considered give fast dynamo action, and magnetic field modes with either sign of magnetic helicity may grow.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 241 , August 1992 , pp. 199 - 214
Copyright
© 1992 Cambridge University Press

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