Spherical convective dynamos in the rapidly rotating asymptotic regime | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Spherical convective dynamos in the rapidly rotating asymptotic regime

Type de publication:

Journal Article

Source:

J. Fluid. Mech., Volume 813, p.558-593 (2017)

Résumé:

<p>Self-sustained convective dynamos in planetary systems operate in an asymptotic regime of rapid rotation, where a balance is thought to hold between the Coriolis, pressure, buoyancy and Lorentz forces (the MAC balance). Classical numerical solutions have previously been obtained in a regime of moderate rotation where viscous and inertial forces are still significant. We define a uni-dimensional path in parameter space between classical models and asymptotic conditions from the requirements to enforce a MAC balance and to preserve the ratio between the magnetic diffusion and convective overturn times (the magnetic Reynolds number). Direct numerical simulations performed along this path show that the spatial structure of the solution at scales larger than the magnetic dissipation length is largely invariant. This enables the definition of large-eddy simulations resting on the assumption that small-scale details of the hydrodynamic turbulence are irrelevant to the determination of the lar</p>