Axisymmetry vs. nonaxisymmetry of hydromagnetic Taylor-Couette flows with axial electric currents

Дата и время публикации : 2013-08-05T16:01:06Z

Авторы публикации и институты :
M. Gellert
I. Tereshin
G. Rüdiger

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 13 pages, 14 figures, submitted to JFM
Первичная категория: physics.flu-dyn

Все категории : physics.flu-dyn, astro-ph.SR

Краткий обзор статьи: The stability of a Taylor-Couette flow with resting outer cylinder under the influence of a homogeneous axial electric current is investigated. In the linear theory the critical Reynolds number for axisymmetric perturbations Re=68 is not influenced by the current-induced magnetic field but all the axisymmetric magnetic perturbations decay. The nonaxisymmetric perturbations with |m|=1 are excited even without rotation for large enough Hartmann numbers (‘Tayler Instability’) but the growth rate increases with Reynolds number. In the nonlinear regime shear energy is pumped into the neighboring modes m=0 and |m|=2. The ratio q of the energy of the magnetic |m|=1 modes and the toroidal background field is very small for the pure (non-rotating) Tayler instability and grows strongly if differential rotation is present. For super-Alfv’enic rotation the energy in the |m|=1 modes of flow and field are in equipartition, with about 1% of the centrifugal energy of the inner cylinder. If the electric current is strong enough to be Tayler unstable then even for very fast rotation kinetic modes and magnetic modes are of the same order of magnitude so that any transport of angular momentum is accompanied by similarly strong mixing (of chemicals).

Category: Physics