Skip to Main content Skip to Navigation
Theses

Magneto-convection dans une sphere en rotation rapide: approches experimentale et numerique de la convection dans les noyaux planetaires

Abstract : MAGNETO-CONVECTION IN A RAPIDLY ROTATING SPHERE: NUMERICAL AND EXPERIMENTAL APPROACHES OF THE CONVECTION IN THE PLANETARY CORES We first study the rapidly rotating developed convection in the non-magnetic case. With the help of a Quasi-Geostrophic numerical code, we have derived a scaling that enhances the role of the thermal non-linearities, whatever the value of the Prandtl number is. The distance from convection onset and the critical Rossby mode seem to define the vortices' intensity and size. These numerical results are in agreement with our experimental measurements, in water and liquid gallium, of the temperature fluctuations and the velocity profiles. Nevertheless some strange behaviours (e.g., intense zonal jets) are detected far from criticallity in water. Our magneto-convection study has been achieved after a modification of our experimental and numerical tools. In agreement with previous asymptotics results, our numerical study separates the modified Rossby modes (weak field case) from the magnetic modes (strong field case). The experimental study, with the help of computations, shows a stabilisation of the developed convection and a modification of the vortices' shape. This inhibition seems mainly to be the consequence of the threshold modification with the imposed field. The numerical study of the convection destabilisation by a strong field leads to similar conclusions. The scalings previously derived in the non-magnetic case thus remains valid with a imposed magnetic field.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00008095
Contributor : Nicolas Gillet <>
Submitted on : Monday, January 17, 2005 - 1:02:35 PM
Last modification on : Thursday, November 19, 2020 - 3:54:28 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:41:20 PM

Identifiers

  • HAL Id : tel-00008095, version 1

Collections

Citation

Nicolas Gillet. Magneto-convection dans une sphere en rotation rapide: approches experimentale et numerique de la convection dans les noyaux planetaires. Géophysique [physics.geo-ph]. Université Joseph-Fourier - Grenoble I, 2004. Français. ⟨tel-00008095⟩

Share

Metrics

Record views

523

Files downloads

322