2004/10/19 by Nathanaël Schaeffer, Nathanael Schaeffer, Schaeffer, Nathanael +2
Biochemistry, Genetics and Molecular Biology · Engineering · Physics and Astronomy · #Astrophysics (astro-ph) #Classical Physics (physics.class-ph) #FOS: Physical sciences #Fluid dynamics and aerodynamics studies #Geomagnetism and Paleomagnetism Studies #Geophysics (physics.geo-ph) #Solar and Space Plasma Dynamics #astro-ph #physics.class-ph #physics.geo-ph
paper · pdf · doi:10.48550/arxiv.physics/0410134
arxiv created 2004/10/19 · openalex publication_date 2004/10/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Rapidly rotating spherical kinematic dynamos are computed using the combination of a quasi geostrophic (QG) model for the velocity field and a classical spectral 3D code for the magnetic field. On one hand, the QG flow is computed in the equatorial plane of a sphere and corresponds to Rossby wave instabilities of a geostrophic internal shear layer produced by differential rotation. On the other hand, the induction equation is computed in the full sphere after a continuation of the QG flow along the rotation axis. Differential rotation and Rossby-wave propagation are the key ingredients of the dynamo process which can be interpreted in terms of αΩ dynamo. Taking into account the quasi geostrophy of the velocity field to increase its time and space resolution enables us to exhibit numerical dynamos with very low Ekman (rapidly rotating) and Prandtl numbers (liquid metals) which are asymptotically relevant to model planetary core dynamos.