The onset of magnetoconvection at large Prandtl number in a rotating layeri. Finite magnetic diffusion

Citation
Ph. Roberts et Ca. Jones, The onset of magnetoconvection at large Prandtl number in a rotating layeri. Finite magnetic diffusion, GEOPH ASTRO, 92(3-4), 2000, pp. 289-325
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS
ISSN journal
0309-1929 → ACNP
Volume
92
Issue
3-4
Year of publication
2000
Pages
289 - 325
Database
ISI
SICI code
0309-1929(2000)92:3-4<289:TOOMAL>2.0.ZU;2-1
Abstract
This paper develops further a convection model that has been studied severa l times previously as a very crude idealization of planetary core dynamics. A plane layer of electrically-conducting fluid rotates about the vertical in the presence of a magnetic field. Such a field can be created spontaneou sly, as in the Childress-Soward dynamo, but here it is uniform, horizontal and externally-applied. The Prandtl number of the fluid is large, but the E kman, Elsasser and Rayleigh numbers are of order unity, as is the ratio of thermal to magnetic diffusivity. Attention is focused on the onset of conve ction as the temperature difference applied across the layer is increased, and on the preferred mode, i.e., the planform and time-dependence of small amplitude convection. The case of main interest is the layer confined betwe en electrically-insulating no-slip walls, but the analysis is guided by a p arallel study based on illustrative boundary conditions that are mathematic ally simpler.