An
oscillatory secondary bifurcation for
magnetoconvection
and
rotating convection at small aspect ratio
Mike Proctor
DAMTP, University of Cambridge, UK
We
consider the dynamics of convection in a strong vertical magnetic field, and in
the presence of rapid rotation. In both these cases, in circumstances which can
be realised in the laboratory, the onset of convection is in the form of tall
thin cells. Because of this, the dynamics near onset is characterised by an
interaction between the
cellular modes and the horizontally averaged
temperature profile. The effects on the dynamics are slight in the case of a
Boussinesq fluid. However in both cases, when the layer is stratified
(non-Boussinesq), the convection can lose stability to oscillations close to
onset. Properties of the oscillations and their stability to long-wavelength
modulation are extensively investigated.