Magnetorotational instability of dissipative couette flow
Jeremy Goodman,Hantao Ji +1 more
TLDR
In this paper, the authors re-examined the stability of viscous resistive magnetized Couette flow with the emphasis on flows that would be hydrodynamically stable according to Rayleigh's criterion: opposing gradient of angular velocity and specific angular momentum.Abstract:
Axisymmetric stability of viscous resistive magnetized Couette flow is re-examined, with the emphasis on flows that would be hydrodynamically stable according to Rayleigh's criterion: opposing gradients of angular velocity and specific angular momentum. In this regime, magnetorotational instabilities (MRI) may occur. Previous work has focused on the Rayleigh-unstable regime. To prepare for an experimental study of MRI, which is of intense astrophysical interest, we solve for global linear modes in a wide gap with realistic dissipation coefficients. Exchange of stability appears to occur through marginal modes. Velocity eigenfunctions of marginal modes are nearly singular at conducting boundaries, but magnetic eigenfunctions are smooth and obey a fourth-order differential equation in the inviscid limit. The viscous marginal system is of tenth order; an eighth-order approximation previously used for Rayleigh-unstable modes does not permit MRI. Peak growth rates are insensitive to boundary conditions. They are predicted with surprising accuracy by WKB methods even for the largest-scale mode. We conclude that MRI is achievable under plausible experimental conditions using easy-to-handle liquid metals such as gallium.read more
Citations
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Enhanced Angular Momentum Transport in Accretion Disks
TL;DR: In this paper, the status of angular momentum transport in accretion disks is reviewed and the last decade has seen a dramatic increase both in the recognition of key physical properties and in the understanding of the transport.
Journal ArticleDOI
Experimental Observation and Characterization of the Magnetorotational Instability
Daniel R. Sisan,Nicolás Mujica,W. Andrew Tillotson,Yi-Min Huang,William Dorland,Adil Hassam,Thomas M. Antonsen,Daniel P. Lathrop +7 more
TL;DR: This work presents the first experimental observation of the magnetorotational instability of liquid sodium between differentially rotating spheres, with an imposed coaxial magnetic field, and characterize the observed patterns, dynamics, and torque increases.
Journal ArticleDOI
Helical magnetorotational instability in magnetized Taylor-Couette flow.
TL;DR: It is shown that in the resistive limit, HMRI is a weakly destabilized inertial oscillation propagating in a unique direction along the axis, and features of HMRI that make it less attractive for experiments and for resistive astrophysical disks are reported.
Journal ArticleDOI
Viscous, Resistive Magnetorotational Modes
Martin E. Pessah,Chi-kwan Chan +1 more
TL;DR: In this article, the behavior of the magnetorotational instability (MRI) in viscous, resistive plasmas was analyzed and the authors provided a geometrical description of these viscous resistive MRI modes and showed how their physical structure is modified as a function of the Reynolds and magnetic Reynolds numbers.
Journal ArticleDOI
Angular momentum transport in protoplanetary and black hole accretion disks: the role of parasitic modes in the saturation of mhd turbulence
TL;DR: In this article, the spectrum and physical structure of parasitic modes that feed off the fastest, exact (primary) MRI mode when its amplitude is such that the fastest parasitic mode grows as fast as the MRI was analyzed.
References
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A powerful local shear instability in weakly magnetized disks. I - Linear analysis. II - Nonlinear evolution
Steven A. Balbus,John F. Hawley +1 more
TL;DR: In this article, a linear analysis is presented of the instability, which is local and extremely powerful; the maximum growth rate which is of the order of the angular rotation velocity, is independent of the strength of the magnetic field.
Journal ArticleDOI
Instability, turbulence, and enhanced transport in accretion disks
Steven A. Balbus,John F. Hawley +1 more
TL;DR: In this paper, a summary of what is now known of disk turbulence and some knotty outstanding questions (e.g., what is the physics behind nonlinear field saturation?) for which we may soon begin to develop answers.
Journal ArticleDOI
Local Three-dimensional Magnetohydrodynamic Simulations of Accretion Disks
Journal ArticleDOI
Dynamo-generated Turbulence and Large-Scale Magnetic Fields in a Keplerian Shear Flow
TL;DR: In this article, the nonlinear evolution of magnetized Keplerian shear fields is simulated in a local, three-dimensional model, including the eeects of compressibility and stratiication.
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