scholarly journals MHD simulations of the magnetorotational instability in a shearing box with zero net flux

2007 ◽  
Vol 476 (3) ◽  
pp. 1113-1122 ◽  
Author(s):  
S. Fromang ◽  
J. Papaloizou
Keyword(s):  
Magnetorotational Instability ◽  
Mhd Simulations ◽  
Net Flux

scholarly journals MHD simulations of the magnetorotational instability in a shearing box with zero net flux

2007 ◽  
Vol 476 (3) ◽  
pp. 1123-1132 ◽  
Author(s):  
S. Fromang ◽  
J. Papaloizou ◽  
G. Lesur ◽  
T. Heinemann
Keyword(s):  
Magnetorotational Instability ◽  
Mhd Simulations ◽  
Net Flux

scholarly journals HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations

2020 ◽  
Vol 497 (1) ◽  
pp. 451-465 ◽  
Author(s):  
Janosz W Dewberry ◽  
Henrik N Latter ◽  
Gordon I Ogilvie ◽  
Sebastien Fromang
Keyword(s):  
Binary Systems ◽  
Wave Excitation ◽  
Mhd Turbulence ◽  
Magnetorotational Instability ◽  
X Ray ◽  
Mhd Simulations ◽  
The Face ◽  
Inertial Wave ◽  
Net Flux ◽  
Magnetohydrodynamic Simulations

ABSTRACT Trapped inertial oscillations (r modes) provide a promising explanation for high-frequency quasi-periodic oscillations (HFQPOs) observed in the emission from black hole X-ray binary systems. An eccentricity (or warp) can excite r modes to large amplitudes, but concurrently, the oscillations are likely damped by magnetohydrodynamic (MHD) turbulence driven by the magnetorotational instability (MRI). We force eccentricity in global, unstratified, zero-net-flux MHD simulations of relativistic accretion discs and find that a sufficiently strong disc distortion generates trapped inertial waves despite this damping. In our simulations, eccentricities above ∼0.03 in the inner disc excite trapped waves. In addition to the competition between r-mode damping and driving, we observe that larger amplitude eccentric structures modify and in some cases suppress MRI turbulence. Given the variety of distortions (warps as well as eccentricities) capable of amplifying r modes, the robustness of trapped inertial wave excitation in the face of MRI turbulence in our simulations provides support for a discoseismic explanation for HFQPOs.

Global Hall-MHD simulations of magnetorotational instability in a plasma Couette flow experiment

2011 ◽  
Vol 18 (6) ◽  
pp. 062904 ◽  
Author(s):  
F. Ebrahimi ◽  
B. Lefebvre ◽  
C. B. Forest ◽  
A. Bhattacharjee
Keyword(s):  
Couette Flow ◽  
Magnetorotational Instability ◽  
Mhd Simulations ◽  
Flow Experiment ◽  
Hall Mhd

scholarly journals 8.10. Three-dimensional global MHD simulations of jet formation in active galactic nuclei

1998 ◽  
Vol 184 ◽  
pp. 363-364
Author(s):  
R. Matsumoto ◽  
K. Shibata
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Three Dimensional ◽  
Galactic Nuclei ◽  
Equatorial Region ◽  
Astrophysical Jets ◽  
Magnetorotational Instability ◽  
Jet Formation ◽  
Mhd Simulations ◽  
Avalanche Flow

Magnetically driven jets from accretion disks are considered to be the most promising models of astrophysical jets. Uchida & Shibata (1985) and Shibata & Uchida (1986) first carried out two-dimensional nonlinear MHD simulations of jet formation from a magnetized disk. Matsumoto et al. (1996) applied the Uchida-Shibata model to a gas torus in active galactic nuclei and showed that the surface layer of the torus accretes faster than the equatorial region like an avalanche because magnetic braking most effectively extracts angular momentum from that layer. A magnetized torus subjects to global non-axisymmetric instabilities (Curry & Pudritz 1996) and local magnetorotational instability (Balbus & Hawley 1991). We carried out three-dimensional global MHD simulations to show the non-axisymmetric effects on the torus, avalanche flow and jet formation.

scholarly journals Magnetic Activity Following Re-Accretion on to Galaxies

2004 ◽  
Vol 217 ◽  
pp. 174-176
Author(s):  
H. Nishikori ◽  
M. Machida ◽  
R. Matsumoto
Keyword(s):  
Magnetic Fields ◽  
Galactic Center ◽  
Plasma Heating ◽  
Three Dimensional ◽  
Magnetic Activity ◽  
Initial Condition ◽  
Disk Drives ◽  
Magnetorotational Instability ◽  
Mhd Simulations ◽  
Dark Matters

We carried out global three-dimensional magnetohydrody-namical (MHD) simulations of galactic gaseous disks re-accreting intergalactic plasma. As the initial condition, we assume that a rotating slender torus is formed at 10kpc from the galactic center. We assume a gravitational potential generated by bulge stars, disk stars and dark matters. Numerical results indicate that magnetorotational instability (MRI) growing in the torus amplifies magnetic fields and generates turbulence. The Maxwell stress enhanced by turbulent magnetic fields drives mass accretion of the disk gas. The amplification of magnetic fields in the accreting gas disk drives magnetic activities such as flares and plasma heating due to magnetic reconnection. The magnetic activity is maintained for time scales longer than the accretion time scale, typically 5Gyr.

scholarly journals 3D MHD simulations of planet migration in turbulent stratified disks

2010 ◽  
Vol 6 (S276) ◽  
pp. 515-516
Author(s):  
Ana Uribe ◽  
Hubert Klahr ◽  
Mario Flock ◽  
Thomas Henning
Keyword(s):  
Numerical Simulations ◽  
Mass Ratio ◽  
Magnetorotational Instability ◽  
Intermediate Mass ◽  
Primary Mass ◽  
Mhd Simulations ◽  
Planet Migration ◽  
Low Mass ◽  
The Times ◽  
Random Fluctuations

AbstractWe performed 3D MHD numerical simulations of planet migration in stratified disks using the Godunov code PLUTO (Mignone et al. 2007). The disk is invaded by turbulence generated by the magnetorotational instability (MRI). We study the migration for planets with different mass to primary mass ratio. The migration of the low-mass planet (q=Mp/Ms=10−5) is dominated by random fluctuations in the torque and there is no defined direction of migration on timescales of 100 orbits. The intermediate-mass planet (q=Mp/Ms=10−4) can experience systematic outwards migration that was sustained for the times we were able to simulate.

scholarly journals Magnetohydrodynamics in a cylindrical shearing box

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Takeru K Suzuki ◽  
Tetsuo Taki ◽  
Scott S Suriano
Keyword(s):  
Mhd Equations ◽  
Radial Dependence ◽  
Mhd Turbulence ◽  
Magnetorotational Instability ◽  
Mhd Simulations ◽  
Self Consistent ◽  
Consistent Manner ◽  
Set Up ◽  
Isothermal Equation ◽  
Physical Quantities

ABSTRACT We develop a framework for magnetohydrodynamical (MHD) simulations in a local cylindrical shearing box by extending the formulation of the Cartesian shearing box. We construct shearing-periodic conditions at the radial boundaries of a simulation box from the conservation relations of the basic MHD equations, taking into account the explicit radial dependence of physical quantities. We demonstrate quasi-steady mass accretion, which cannot be handled by the standard Cartesian shearing box model, with an ideal MHD simulation in a vertically unstratified cylindrical shearing box for up to 200 rotations. In this demonstrative run we set up (i) net vertical magnetic flux, (ii) a locally isothermal equation of state, and (iii) a sub-Keplerian equilibrium rotation, whereas the sound velocity and the initial Alfvén velocity have the same radial dependence as that of the Keplerian velocity. Inward mass accretion is induced to balance the outward angular momentum flux of the MHD turbulence triggered by the magnetorotational instability in a self-consistent manner. We discuss detailed physical properties of the saturated magnetic field, in comparison to the results of a Cartesian shearing box simulation.

scholarly journals Recent results from simulations of the magnetorotational instability

2010 ◽  
Vol 6 (S274) ◽  
pp. 422-428 ◽  
Author(s):  
James M. Stone
Keyword(s):  
Particle Acceleration ◽  
First Principles ◽  
Mhd Turbulence ◽  
Magnetorotational Instability ◽  
Nonlinear Saturation ◽  
Global Models ◽  
Mhd Simulations ◽  
Control Saturation ◽  
Future Work ◽  
Local Shearing

AbstractThe nonlinear saturation of the magnetorotational instability (MRI) is best studied through numerical MHD simulations. Recent results of simulations that adopt the local shearing box approximation, and fully global models that follow the entire disk, are described. Outstanding issues remain, such as a first-principles understanding of the dynamo processes that control saturation with no net magnetic flux. Important directions for future work include a better understanding of basic plasma processes, such as reconnection, dissipation, and particle acceleration, in the MHD turbulence driven by the MRI.

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