Self-Similar Turbulent Dynamo

Alexander A. Schekochihin, Steven C. Cowley, Jason L. Maron, James C. McWilliams

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The amplification of magnetic fields in a highly conducting fluid is studied numerically. During growth, the magnetic field is spatially intermittent: it does not uniformly fill the volume, but is concentrated in long thin folded structures. Contrary to a commonly held view, intermittency of the folded field does not increase indefinitely throughout the growth stage if diffusion is present. Instead, as we show, the probability-density function (PDF) of the field-strength becomes self-similar. The normalized moments increase with magnetic Prandtl number in a powerlike fashion. We argue that the self-similarity is to be expected with a finite flow scale and system size. In the nonlinear saturated state, intermittency is reduced and the PDF is exponential. Parallels are noted with self-similar behavior recently observed for passive-scalar mixing and for map dynamos.

Original languageEnglish (US)
JournalPhysical review letters
Volume92
Issue number6
DOIs
StatePublished - 2004

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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