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Low magnetic Prandtl number dynamos with helical forcing

Pablo D. Mininni1 and David C. Montgomery2

  • 1National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307, USA
  • 2Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755, USA

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Phys. Rev. E 72, 056320 – Published 18 November, 2005

DOI: https://doi.org/10.1103/PhysRevE.72.056320

Abstract

We present direct numerical simulations of dynamo action in a forced Roberts flow. The behavior of the dynamo is followed as the mechanical Reynolds number is increased, starting from the laminar case until a turbulent regime is reached. The critical magnetic Reynolds for dynamo action is found, and in the turbulent flow it is observed to be nearly independent on the magnetic Prandtl number in the range from ∼0.3 to ∼0.1. Also the dependence of this threshold with the amount of mechanical helicity in the flow is studied. For the different regimes found, the configuration of the magnetic and velocity fields in the saturated steady state are discussed.

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Outline

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Phys. Rev. E 72, 056320– Published 18 November, 2005
  • Received 5 May 2005

© 2005 American Physical Society

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