Large-scale magnetic field saturation and the Elsasser number in rotating spherical dynamo models

Autor:	Nicholas A. Featherstone, Ryan J. Orvedahl, Michael A. Calkins
Rok vydání:	2021
Předmět:	Physics Convection Scale (ratio) Space and Planetary Science Astronomy and Astrophysics Astrophysics Mechanics Magnetohydrodynamics Saturation (chemistry) Physics::Geophysics Dynamo Magnetic field
Zdroj:	Monthly Notices of the Royal Astronomical Society: Letters. 507:L67-L71
ISSN:	1745-3933 1745-3925
Popis:	Numerical simulations are used to investigate large-scale (mean) magnetic field generation in rotating spherical dynamos. Beyond a certain threshold, we find that the magnitude of the mean magnetic field becomes nearly independent of the system rotation rate and buoyancy forcing. The analysis suggests that this saturation arises from the Malkus-Proctor mechanism in which a Coriolis-Lorentz force balance is achieved in the zonal component of the mean momentum equation. When based on the large-scale magnetic field, the Elsasser number is near unity in the saturated regime. The results show that the large and small magnetic field saturate via distinct mechanisms in rapidly rotating dynamos, and that only the axisymmetric component of the magnetic field appears to follow an Elsasser number scaling.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::1b978de1299682975aece1119660ffff https://doi.org/10.1093/mnrasl/slab097 Zobrazit plný text záznamu