Philip Livermore ,  University of Leeds

 
Kinematic theory is a simplification of the full MHD problem in which the flow
of conducting fluid in the Earth's outer core is prescribed, and only the time
evolution of the magnetic field is sought. Traditionally, linear stability
analysis has been used with a certain amount of success, although typical results
show critical dependence on the precise choice of flow. Fluid dynamical studies
have shown that finite time transient behaviour, differing from the results of linear analysis,
may be of fundamental importance
in understanding the growth of instabilities in non-magnetic flow. I present
results of applying similar techniques to the magnetic case, in particular
demonstrating robust growth of axisymmetric fields which may go some way in
explaining their dominance in the geomagnetic field.