http://arxiv.org/abs/1504.07835
We present a set of convective dynamo simulations in rotating spherical fluid shells based on an anelastic approximation of compressible fluids. The simulations extend into a “buoyancy-dominated” regime where the buoyancy forcing is dominant while the Coriolis force is no longer balanced by pressure gradients and strong anti-solar differential rotation develops as a result. Dynamos in this regime are strongly dominated by dipole components but at the same time their magnetic energies are relatively small compared to the corresponding kinetic energies of the flow. Despite being relatively weak the self-sustained magnetic fields are able to reverse the direction of differential rotation to solar-like. We find that the convection in the buoyancy-dominated regime is significantly stronger near the pole than in the equatorial region, leading to non-oscillatory dipolar dynamo solutions. The results are obtained with a new simulation code for modelling of convection and MHD dynamo generation in rotating spherical shells under the anelastic approximation. The model equations and the new code are also presented here along with code validation results based on benchmark dynamo models.
R. Simitev, A. Kosovichev and F. Busse
Thu, 30 Apr 15
41/43
Comments: 4 figures and 2 tables