Oscillatory migrating magnetic fields in helical turbulence in spherical domains
Abstract
We present direct numerical simulations of the equations of compressible magnetohydrodynamics in a wedge-shaped spherical shell, without shear, but with random helical forcing which has negative (positive) helicity in the northern (southern) hemisphere. We find a large-scale magnetic field that is nearly uniform in the azimuthal direction and approximately antisymmetric about the equator. Furthermore, the large-scale field in each hemisphere oscillates on nearly dynamical time scales with reversals of polarity and equatorward migration. Corresponding mean-field models also show similar migratory oscillations with a frequency that is nearly independent of the magnetic Reynolds number. This mechanism may be relevant for understanding equatorward migration seen in the solar dynamo.
Cite
@article{arxiv.0901.2364,
title = {Oscillatory migrating magnetic fields in helical turbulence in spherical domains},
author = {Dhrubaditya Mitra and Reza Tavakol and Petri J. Käpylä and Axel Brandenburg},
journal= {arXiv preprint arXiv:0901.2364},
year = {2015}
}
Comments
Consistent with the published verstion (emulateapj)