Issue |
A&A
Volume 411, Number 3, December I 2003
|
|
---|---|---|
Page(s) | 321 - 327 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20031371 | |
Published online | 17 November 2003 |
Turbulent magnetic Prandtl number and magnetic diffusivity quenching from simulations
1
Department of Energy and Process Engineering, Norwegian University of Science and Technology, Kolbjørn Hejes vei 2B, 7491 Trondheim, Norway
2
NORDITA, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark
3
Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
Received:
21
February
2003
Accepted:
25
August
2003
Forced turbulence simulations are used to determine the
turbulent kinematic viscosity, , from the
decay rate of a large scale velocity field.
Likewise, the turbulent magnetic diffusivity,
,
is determined from the decay of a large scale magnetic field.
In the kinematic regime, when the field is weak, the turbulent
magnetic Prandtl number,
, is about unity.
When the field is nonhelical,
is quenched when
magnetic and kinetic energies become comparable.
For helical fields the quenching is stronger and can be described
by a dynamical quenching formula.
Key words: magnetohydrodynamics (MHD) / turbulence
© ESO, 2003
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