Journal title
Journal of Fluid Mechanics
DOI
10.1017/jfm.2017.324
Volume
822
Last updated
2024-03-27T10:05:07.87+00:00
Page
822R31-822R310
Abstract
© 2017 Cambridge University Press. We demonstrate that the critical magnetic Reynolds number Rm c for a turbulent nonhelical dynamo in the limit of low magnetic Prandtl number Pm (i.e. Pm=Rm/Re ≪ 1) can be significantly reduced if the flow is subjected to global rotation. Even for moderate rotation rates the required energy injection rate can be reduced by a factor of more than 10 3 . This strong decrease in the onset is attributed to the transfer of energy to the large scales, forming a large-scale condensate, and the reduction in the turbulent fluctuations that cause the flow to have a much larger cutoff length scale than in a non-rotating flow of the same Reynolds number. The dynamo thus behaves as if it is driven just by the large scales that act as a laminar flow (i.e. it behaves as a high Pm dynamo) even though the actual Reynolds number is much higher than the magnetic Reynolds number (i.e. low Pm). Our finding thus points to a new paradigm for the design of new experiments on liquid metal dynamos.
Symplectic ID
732156
Submitted to ORA
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Publication type
Journal Article
Publication date
10 Jul 2017