Self-similar turbulent dynamo.

Journal article

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.

Authors: Schekochihin, A; Cowley, S; Maron, J; McWilliams, J

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 92
• Issue: 6
• Pages: 064501
• Publication date: 2004-02-01
• DOI: 10.1103/physrevlett.92.064501
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: physics.flu-dyn; nlin.CD; astro-ph