Abstract
This study considers the onset of stress-free Boussinesq thermal convection in rotating spherical shells with an aspect ratio ( and being the inner and outer radius), Prandtl numbers , and Taylor numbers . We are particularly interested in the form of the convective cell pattern that develops, and in its time scales, since this may have observational consequences. For a fixed and by decreasing from 0.1 to , a transition between spiraling columnar (SC) and equatorially attached (EA) modes, and a transition between EA and equatorially antisymmetric or symmetric polar (AP/SP) weakly multicellular modes, are found. The latter modes are preferred at very low . Surprisingly, for , the unicellular polar modes become also preferred at moderate because two new transition curves between EA and AP/SP and between AP/SP and SC modes are born at a triple-point bifurcation. The dependence on and of the transitions is studied to estimate the types of modes, and their critical parameters, preferred at different stellar regimes.
1 More- Received 6 September 2017
DOI:https://doi.org/10.1103/PhysRevFluids.3.024801
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