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Cellular Dynamo in a Rotating Spherical Shell Alexander Getling Lomonosov Moscow State University Moscow, Russia Radostin Simitev, Friedrich Busse University of Bayreuth, Germany. The problem of solar dynamo: interplay between global and local magnetic fields needs to be included.
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Cellular Dynamo in a RotatingSpherical ShellAlexander GetlingLomonosov Moscow State UniversityMoscow, RussiaRadostin Simitev,Friedrich Busse University of Bayreuth, Germany
The problem of solar dynamo:interplay between global and local magnetic fields needs to be included Mean-field electrodynamics → no local fields considered Possible alternative → “deterministic” dynamo with well-defined structural elements in the flow and magnetic field
Kinematic model of cellular dynamo(cell = toroidal eddy): A.V. Getling and B.A. Tverskoy, Geomagn. Aeron. 11, 211, 389 (1971)
Convective mechanism of magnetic-field amplification and structuring
This study is based on numerical simulations of cellular magnetoconvection in a rotating spherical shell
The problem • Spherical fluid shell • Stress-free, electrically insulating boundaries with perfect heat conductivity • Uniformly distributed internal heat sources • Boussinesq approximation • A small quadratic term is present in thetemperaturedependence of density
The case discussed here Geometrical parameter: η = 0.6 Physical parameters: Ri = 3000, Re = − 6000, τ= 10, P= 1, Pm=30 Computational parameter: m = 5
Pseudospectral code employed: F.H. Busse, E. Grote, and A. Tilgner,Stud. Geophys. Geod.42, 211 (1998)
Radial velocity at r=ri+0.5d t = 98.73
Radial magnetic field at r=ro+0.7d t = 98.73 t = 101.73
Azimuthal magnetic field and meridional field lines t = 95.73 t = 101.73
Variations in dipolar-field energy axisymm. pol. axisymm. tor. asymm. pol. asymm. tor.