Proceedings of the International Astronomical Union

Table of Contents - 01 June 2010 - Volume 6, Symposium S271 (Astrophysical Dynamics: From Stars to Galaxies)  

Contributed Papers

Nonlinear Dynamos

David Gallowaya1

a1 School of Mathematics and Statistics, University of Sydney, NSW 2006, Australia email: dave@maths.usyd.edu.au

Abstract

This paper discusses nonlinear dynamos where the nonlinearity arises directly via the Lorentz force in the Navier-Stokes equation, and leads to a situation where the Lorentz force and the velocity and the magnetic field are in direct competition over substantial regions of the flow domain. Filamentary and non-filamentary dynamos are contrasted, and the concept of Alfvénic dynamos with almost equal magnetic and kinetic energies is reviewed via examples. So far these remain in the category of toy models; the paper concludes with a discussion of whether similar dynamos are likely to exist in astrophysical objects, and whether they can model the solar cycle.

(Online publication August 12 2011)

Keywords

  • magnetic fields;
  • MHD;
  • Sun: magnetic fields;
  • stars: magnetic fields