Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-11-03
Mon.Not.Roy.Astron.Soc. 325 (2001) 685-692
Astronomy and Astrophysics
Astrophysics
8 pages, 11 figs, submitted to MN (revised, newly added Sect 6)
Scientific paper
10.1046/j.1365-8711.2001.04468.x
The evolution of magnetic fields is studied using simulations of forced helical turbulence with strong imposed shear. After some initial exponential growth, the magnetic field develops a large scale travelling wave pattern. The resulting field structure possesses magnetic helicity, which is conserved in a periodic box by the ideal MHD equations and can hence only change on a resistive time scale. This constrains strongly the growth time of the large scale magnetic field, but less strongly the length of the cycle period. Comparing with the case without shear, the time scale for large scale field amplification is shortened by a factor Q, which depends on the relative importance of shear and helical turbulence, and which controls also the ratio of toroidal to poloidal field. The results of the simulations can be reproduced qualitatively and quantitatively with a mean-field alpha-Omega dynamo model with alpha-effect and the turbulent magnetic diffusivity coefficients that are less strongly quenched than in the corresponding alpha^2-dynamo.
Bigazzi Alberto
Brandenburg Axel
Subramanian Kandaswamy
No associations
LandOfFree
The helicity constraint in turbulent dynamos with shear does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The helicity constraint in turbulent dynamos with shear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The helicity constraint in turbulent dynamos with shear will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-111864