dorsal/arxiv
View SchemaQuasi-geostrophic kinematic dynamos at low magnetic Prandtl number
| Authors | Nathanael Schaeffer, Philippe Cardin |
|---|---|
| Categories | |
| ArXiv ID | physics/0410134 |
| URL | https://arxiv.org/abs/physics/0410134 |
Abstract
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 $\alpha\Omega$ 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.
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"abstract": "Rapidly rotating spherical kinematic dynamos are computed using the\ncombination of a quasi geostrophic (QG) model for the velocity field and a\nclassical spectral 3D code for the magnetic field. On one hand, the QG flow is\ncomputed in the equatorial plane of a sphere and corresponds to Rossby wave\ninstabilities of a geostrophic internal shear layer produced by differential\nrotation. On the other hand, the induction equation is computed in the full\nsphere after a continuation of the QG flow along the rotation axis.\nDifferential rotation and Rossby-wave propagation are the key ingredients of\nthe dynamo process which can be interpreted in terms of $\\alpha\\Omega$ dynamo.\nTaking into account the quasi geostrophy of the velocity field to increase its\ntime and space resolution enables us to exhibit numerical dynamos with very low\nEkman (rapidly rotating) and Prandtl numbers (liquid metals) which are\nasymptotically relevant to model planetary core dynamos.",
"arxiv_id": "physics/0410134",
"authors": [
"Nathanael Schaeffer",
"Philippe Cardin"
],
"categories": [
"physics.class-ph",
"astro-ph",
"physics.geo-ph"
],
"title": "Quasi-geostrophic kinematic dynamos at low magnetic Prandtl number",
"url": "https://arxiv.org/abs/physics/0410134"
},
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