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

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.

4 pages, 4 figures

References in corpus (4)

• On magnetic field generation in Kolmogorov turbulence
• Large scale flow effects, energy transfer, and self-similarity on turbulence
• Influence of turbulence on the dynamo threshold
• Numerical simulations of current generation and dynamo excitation in a mechanically-forced, turbulent flow

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