Sensitivity to luminosity, centrifugal force, and boundary conditions in spherical shell convection
Abstract
We test the sensitivity of hydrodynamic and magnetohydrodynamic turbulent convection simulations with respect to Mach number, thermal and magnetic boundary conditions, and the centrifugal force. We find that varying the luminosity, which also controls the Mach number, has only a minor effect on the largescale dynamics. A similar conclusion can also be drawn from the comparison of two formulations of the lower magnetic boundary condition with either vanishing electric field or current density. The centrifugal force has an effect on the solutions, but only if its magnitude with respect to acceleration due to gravity is by two orders of magnitude greater than in the Sun. Finally, we find that the parameterisation of the photospheric physics, either by an explicit cooling term or enhanced radiative diffusion, is more important than the thermal boundary condition. In particular, runs with cooling tend to lead to more anisotropic convection and stronger deviations from the TaylorProudman state. In summary, the fully compressible approach taken here with the Pencil Code is found to be valid, while still allowing the disparate timescales to be taken into account.
 Publication:

Geophysical and Astrophysical Fluid Dynamics
 Pub Date:
 March 2020
 DOI:
 10.1080/03091929.2019.1571586
 arXiv:
 arXiv:1807.09309
 Bibcode:
 2020GApFD.114....8K
 Keywords:

 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 26 pages, 14 figures, accepted to GAFD Special issue on 'Physics and Algorithms of the Pencil Code'