Phys. Rev. Lett. 101, 144502 (2008) [4 pages]Bypassing Cowling’s Theorem in Axisymmetric Fluid DynamosReceived 9 May 2008; published 1 October 2008 We present a numerical study of the magnetic field generated by an axisymmetrically forced flow in a spherical domain. We show that, even in the absence of nonaxisymmetric velocity fluctuations, a mean magnetic field with a dominant axisymmetric dipolar component can be generated via a secondary bifurcation from an equatorial dipole. We understand the dynamical behaviors that result from the interaction of equatorial and axial dipolar modes using simple model equations for their amplitudes derived from symmetry arguments. © 2008 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.101.144502
DOI:
10.1103/PhysRevLett.101.144502
PACS:
47.65.−d, 52.65.Kj, 91.25.Cw
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