Quasi-stationary and chaotic convection in low rotating spherical shells

Summary

The geophysical flow simulation experiment ‘GeoFlow’ studies convection phenomena in rotating spherical shells under influence of a spherical symmetric buoyancy field. It is a space station experiment, that is backed by three-dimensional numerical simulation done with a spectral code. Here we present simulated dynamics in the low rotational regime. Flow patterns are characterized by solutions of axisymmetric, cubic and pentagonal symmetry with adjustment to rotating axes. For the example of a cubic pattern in supercritical convection regime, the evolution of heat transfer and kinetic energy is discussed, if the rotational influence increases. While these global variables point out that the flow is stationary in the rotating reference frame, it is the local variable of spherical harmonics in azimuthal direction which shows a periodic drift, i.e. the pattern is counter rotating to the sphere. Transition to chaos is in form of a sudden onset.