Nonlinear Evolution of Axisymmetric Twisted Flux Tubes in the Solar Tachocline
We numerically study the evolution of magnetic fields and fluid flows in a thin spherical shell. We take the initial field to be a latitudinally confined, predominantly toroidal flux tube. For purely toroidal, untwisted flux tubes, we recover previously known radial-shredding instabilities, and show further that in the nonlinear regime these instabilities can very effectively destroy the original field. For twisted flux tubes, also including a poloidal component, there are several possibilities, including the suppression of the radial-shredding instability, but also a more directly induced evolution, brought about because twisted flux tubes in general are not equilibrium solutions of the governing equations.
KeywordsInterior, tachocline Instabilities Magnetohydrodynamics
Unable to display preview. Download preview PDF.