http://arxiv.org/abs/2305.01312
The centrifugal force is often omitted in simulations of stellar convection. This force might be important in rapidly rotating stars such as solar analogues due to its $\Omega^2$ scaling, where $\Omega$ is the rotation rate of the star. We study the effects of the centrifugal force in a set of 21 semi-global stellar dynamo simulations with varying rotation rates. Among these, we include three control runs aimed at distinguishing the effects of the centrifugal force from the nonlinear evolution of the solutions. We solve the 3D MHD equations with the Pencil Code in a solar-like convective zone in a spherical wedge setup with a $2\pi$ azimuthal extent. We decompose the magnetic field in spherical harmonics and study the migration of azimuthal dynamo waves (ADWs), energy of different large-scale magnetic modes, and differential rotation. In the regime with the lowest rotation rates, $\Omega = 5-10\Omega_\odot$, where $\Omega_\odot$ is the rotation rate of the Sun, we see no marked changes in neither the differential rotation nor the magnetic field properties. For intermediate rotation with $\Omega = 20-25\Omega_\odot$ we identify an increase of the differential rotation as a function of centrifugal force. The axisymmetric magnetic energy tends to decrease with centrifugal force while the non-axisymmetric one increases. The ADWs are also affected, especially the propagation direction. In the most rapidly rotating set with $\Omega=30\Omega_\odot$, these changes are more pronounced and in one case the propagation direction of the ADW changes from prograde to retrograde. Control runs suggest that the results are a consequence of the centrifugal force and not due to the details of the initial conditions or the history of the run. We find that the differential rotation and properties of the ADWs change as a function of the centrifugal force only when rotation is rapid enough.
F. Navarrete, P. Käpylä, D. Schleicher, et. al.
Wed, 3 May 23
48/67
Comments: 8 pages, 7 figures, submitted to A&A