The onset of turbulent rotating dynamos at the low $Pm$ limit

Abstract

We demonstrate that the critical magnetic Reynolds number $R{m}_c$ for a turbulent non-helical dynamo in the low magnetic Prandtl number $Pm$ limit (i.e. $Pm=Rm/Re\ll 1$) can be significantly reduced if the flow is submitted to global rotation. Even for moderate rotation rates the required energy injection rate can be reduced by a factor more than $10^3$. This strong decrease of the onset is attributed to the reduction of the turbulent fluctuations that makes the flow to have a much larger cut-off length-scale compared to a non-rotating flow of the same Reynolds number. The dynamo thus behaves as if it is driven by laminar behaviour (i.e. high $Pm$ behaviour) even at high values of the Reynolds number (i.e. at low values of $Pm$). Our finding thus points into a new paradigm for the design of new liquid metal dynamo experiments.

5 pages, 6 figures

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Cited by in corpus (6)

• Dynamo theories
• The Turbulent Dynamo
• Condensates in rotating turbulent flows
• Joint Instability and Abrupt Nonlinear Transitions in a Differentially Rotating Plasma
• Inverse cascade of hybrid helicity in $B\Omega$-MHD turbulence
• Principle of Helical \& Nonhelical Dynamo and $\alpha$ effect in Field Structure model