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Updated: May 23, 2026
06:42
Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
Magnetized stratified rotating shear waves
A Salhi1, T Lehner, F Godeferd
1Département de Physique, Faculté des Sciences de Tunis, 1060 Tunis, Tunisia.
Summary
This study analyzes fluid behavior under shear, rotation, stratification, and magnetic fields, revealing how stratification affects magnetorotational instability (MRI). Vertical stratification inhibits MRI less than radial stratification, with implications for astrophysical disks.
Area of Science:
- Astrophysics
- Fluid Dynamics
- Plasma Physics
Background:
- Astrophysical fluids are subject to complex forces including shear, rotation, stratification, and magnetic fields.
- Understanding instabilities like the magnetorotational instability (MRI) is crucial for phenomena in accretion disks.
- Linear spectral theory and the shearing box model are common frameworks for studying these systems.
Purpose of the Study:
- To present a spectral linear analysis of fluid behavior under combined shear, rotation, stratification, and magnetic fields.
- To investigate the impact of radial and vertical stratification on the magnetorotational instability (MRI).
- To analyze the stability of magnetized stratified Keplerian disks and energy dynamics.
Main Methods:
- Utilized spectral linear analysis with advected Fourier modes within the shearing box model.
- Derived a four-component linear differential system incorporating buoyancy and potential magnetic induction.
- Studied stability for both axisymmetric (k(1)=0) and nonaxisymmetric (k(1)≠0) disturbances, employing Levinson's theorem for the latter.
Main Results:
- Purely radial stratification inhibits MRI, while purely vertical stratification does not completely suppress it.
- Demonstrated stability for nonaxisymmetric disturbances with vertical stratification at infinite vertical wavelength, showing oscillatory behavior.
- Identified rapid transient growth in horizontal motion due to aperiodic vortex modes, with energy contributions from low streamwise and vertical wavenumbers.
Conclusions:
- The study provides a detailed characterization of MRI in stratified, magnetized fluids.
- Results offer insights into turbulence generation via bypass mechanisms in astrophysical disks.
- The model shows quantitative agreement with direct numerical simulations for energy spectra in magnetized Keplerian disks.
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