Issue |
A&A
Volume 397, Number 2, January II 2003
|
|
---|---|---|
Page(s) | 393 - 399 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20021568 | |
Published online | 17 December 2002 |
Numerical simulations of kinematic dynamo action
1
Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Spain
2
The Institute for Solar Physics of the Royal Swedish Academy of Sciences, SCFAB, 10691 Stockholm, Sweden
3
The Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
Corresponding author: V .D. Archontis, vasilis@ll.iac.es
Received:
2
May
2002
Accepted:
21
October
2002
Numerical simulations of kinematic dynamo action in
steady and three-dimensional ABC flows are presented with special
focus on the difference in growth rates between cases with single
and multiple periods of the prescribed velocity field. It is found
that the difference in growth rate (apart from a trivial factor
stemming from a scaling of the rate of strain with the wavenumber
of the velocity field) is due to differences in the recycling of
the weakest part of the magnetic field. The single wavelength
classical ABC-flow experiments impose stronger symmetry
requirements, which results in a suppression of the growth rate.
The experiments with larger wave number achieve growth rates that
are more compatible with the turn-over time scale by breaking the
symmetry of the resulting dynamo-generated magnetic field.
Differences in topology in cases with and without stagnation
points in the imposed velocity field are also investigated, and it
is found that the cigar-like structures that develop in the
classical dynamos are replaced by ribbon structures in
cases where the flow is without stagnation points.
Key words: diffusion / magnetic fields / magnetohydrodynamics (MHD) / turbulence / plasmas
© ESO, 2003
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