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Dynamo action at low magnetic Prandtl numbers: mean flow vs. fully turbulent motion

Yannick Ponty·Pablo Mininni·Jean-François Pinton·Hélène Politano·Annick Pouquet
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Abstract

We compute numerically the threshold for dynamo action in Taylor-Green swirling flows. Kinematic calculations, for which the flow field is fixed to its time averaged profile, are compared to dynamical runs for which both the Navier-Stokes and the induction equations are jointly solved. The kinematic instability is found to have two branches, for all explored Reynolds numbers. The dynamical dynamo threshold follows these branches: at low Reynolds number it lies within the low branch while at high kinetic Reynolds number it is close to the high branch.

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Yannick Ponty, Pablo Mininni, Jean-François Pinton, Hélène Politano, Annick Pouquet. 2006-01-16. Dynamo action at low magnetic Prandtl numbers: mean flow vs. fully turbulent motion. https://doi.org/10.1088/1367-2630%2F9%2F8%2F296

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