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.
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Submitted to: Physical Review Letters (January 2014)
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