Issue
EPL
Volume 85, Number 1, January 2009
Article Number 19001
Number of page(s) 5
Section Geophysics, Astronomy and Astrophysics
DOI http://dx.doi.org/10.1209/0295-5075/85/19001
Published online 16 January 2009
EPL, 85 (2009) 19001
DOI: 10.1209/0295-5075/85/19001

Bistability and hysteresis of dipolar dynamos generated by turbulent convection in rotating spherical shells

R. D. Simitev1 and F. H. Busse2

1   Department of Mathematics, University of Glasgow - Glasgow G12 8QW, UK, EU
2   Institute of Physics, University of Bayreuth - Bayreuth D-95440, Germany, EU

r.simitev@maths.gla.ac.uk

received 4 October 2008; accepted in final form 28 November 2008; published January 2009
published online 16 January 2009

Abstract
Bistability and hysteresis of magnetohydrodynamic dipolar dynamos generated by turbulent convection in rotating spherical fluid shells is demonstrated. Hysteresis appears as a transition between two distinct regimes of dipolar dynamos with rather different properties including a pronounced difference in the amplitude of the axisymmetric poloidal field component and in the form of the differential rotation. The bistability occurs from the onset of dynamo action up to about 9 times the critical value of the Rayleigh number for onset of convection and over a wide range of values of the ordinary and the magnetic Prandtl numbers including the value unity.

PACS
91.25.Cw - Origins and models of the magnetic field; dynamo theories.
92.60.hk - Convection, turbulence, and diffusion.
47.20.Ky - Nonlinearity, bifurcation, and symmetry breaking.

© EPLA 2009