Linear and nonlinear instability in a cylindrical enclosure caused by a rotating magnetic field

Rotating magnetic fields generate a swirling motion in electrically conductive fluids. In previous theoretical and experimental studies this flow was found to be susceptible to non-normal nonlinear transition mechanisms, which are triggered by small perturbations. In this Brief Communication we present a numerical investigation of the transition in a closed cylindrical container. Depending on the magnetic Taylor number, three different scenarios have been identified: a single subcritical burst, a series of supercritical bursts and, at higher Taylor numbers, a sustained unsteady regime. In all three cases, the unsteady stages are governed by Taylor-Gortler vortices.(c) 2007 American Institute of Physics.