ELFT HÍRADÓ

[StatFizSzeminar <statfiz AT glu.elte.hu>]

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                   ELTE Institute of Physics
                SEMINARS IN STATISTICAL PHYSICS


                        2 September 2015
                       Wednesday, 11 a.m.

                          Fred Feudel

    Universität Potsdam, Institut für Physik und Astronomie

  "Dynamo bifurcations in rotating spherical shell convection"


It is generally accepted that dynamo action is responsible for the existence 
of
large-sale magnetic fields in diverse astrophysical objects, an example is the
outer core of the Earth. In the classical model, the dynamo is driven by the
motion of an electrically conductive fluid via electromagnetic induction in a
rotating spherical shell, as described by the magneto-hydrodynamic equations. 
We
study both the nonmagnetic branches which bifurcate primarily from the
conductive state and secondary branches bifurcating from the convective states
which generate eventually the magnetic solutions. For this purpose we
implemented a path-following code which uses Newton methods to trace 
stationary
states and rotating waves (RWs) in order to detect bifurcations of magnetic
branches. In particular we investigate the influence of the rotation rate on
these secondary bifurcations and demonstrate how the supercritcal bifurcations
of dynamo solutions for low rotation rates turn to subcritical bifurcations 
for
higher rotation rates. In the latter case the dynamo is stabilized over a
further saddle node bifurcation.


                          Room 2.54
     1117 Budapest, Pázmány P. sétány 1/A (Northern Block)
              home page: http://glu.elte.hu/~statfiz


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