PPPL-4982

Nonmodal Growth Of The Magneto-rotational Instability

Authors: J. Squire and A. Bhattacharjee

Abstract:
We analyze the linear growth of the magneto-rotational instability (MRI) in the short time limit using nonmodal methods. Our findings are quite di erent to standard results, illustrating that shearing wave energy can grow at the maximum MRI rate, -dΩ /d In r for any choice of azimuthal and vertical wavelengths. In addition, by comparing the growth of shearing waves with static eigenmode-like structures, we show that over short time-scales shearing waves will always be dynamically more important than static structures in the ideal limit. By demonstrating that some fast linear growth is possible at all wavelengths, these results suggest that nonmodal linear physics could play a fundamental role in MRI turbulence.
__________________________________________________

Submitted to: Physical Review Letters (January 2014)

__________________________________________________

Download PPPL-4982 (pdf 265 KB 14 pp)
__________________________________________________