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Hot accretion flows contain collisionless plasmas that are believed to be capable of accelerating particles to very high energies, as a result of turbulence generated by the magnetorotational instability (MRI). We conduct unstratified…

High Energy Astrophysical Phenomena · Physics 2021-07-14 Xiaochen Sun , Xue-Ning Bai

An important idea underlying a plausible dynamical theory of circulation in three-dimensional turbulence is the so-called Area Rule, according to which the probability density function (PDF) of the circulation around closed loops depends…

Fluid Dynamics · Physics 2021-10-22 Kartik P. Iyer , Sachin S. Bharadwaj , Katepalli R. Sreenivasan

Bearing in mind the application to core-collapse supernovae, we study nonlinear properties of the magneto-rotational instability (MRI) by means of three- dimensional simulations in the framework of a local shearing box approximation. By…

Solar and Stellar Astrophysics · Physics 2015-06-11 Y. Masada , T. Takiwaki , K. Kotake , T. Sano

The evolution of warped disks is governed by internal, oscillatory shear flows driven by their distorted geometry. However, these flows are known to be vigorously unstable to a hydrodynamic parametric instability. In many warped systems,…

Solar and Stellar Astrophysics · Physics 2025-08-25 Callum W. Fairbairn , James M. Stone

We propose that the strength of angular momentum transport in accretion discs threaded by net vertical magnetic field is determined by a self-regulation mechanism: the magnetorotational instability (MRI) grows until its own turbulent…

High Energy Astrophysical Phenomena · Physics 2023-04-18 Mitchell C. Begelman , Philip J. Armitage

Macroscopic gas motions are widespread throughout the solar atmosphere and shearing motions couple to the non--ideal effects, destabilising low frequency fluctuations in the medium. The origin of this non-ideal magnetohydrodynamic…

Solar and Stellar Astrophysics · Physics 2015-06-05 B. P. Pandey , Mark Wardle

The physical modeling of the accretion disk boundary layer, the region where the disk meets the surface of the accreting star, usually relies on the assumption that angular momentum transport is opposite to the radial angular frequency…

High Energy Astrophysical Phenomena · Physics 2012-11-28 Chi-kwan Chan , Martin E. Pessah

We present three-dimensional magnetohydrodynamic simulations of the nonlinear evolution of the magnetorotational instability (MRI) with a non-zero Ohmic resistivity. The properties of the saturated state depend on the initial magnetic field…

Astrophysics · Physics 2009-10-31 Timothy P. Fleming , James M. Stone , John F. Hawley

We investigate the effect of shear viscosity and Ohmic resistivity on the magnetorotational instability (MRI) in vertically stratified accretion disks through a series of local simulations with the Athena code. First, we use a series of…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Jacob B. Simon , John F. Hawley , Kris Beckwith

Using local 3D MHD simulations, we investigate ways in which galactic turbulence associated with the magnetorotational instability (MRI) may influence the formation and properties of GMCs. Our disk models are vertically stratified and…

Astrophysics · Physics 2009-11-10 Woong-Tae Kim , Eve C. Ostriker , James M. Stone

We perform numerical simulations of magneto-rotational instability in a local patch of accretion disk in which radiation pressure exceeds gas pressure. Such conditions may occur in the central regions of disks surrounding compact objects in…

Astrophysics · Physics 2007-05-23 N. J. Turner , J. M. Stone , T. Sano

(abridged) Angular momentum transport and accretion in protoplanetary discs are generally believed to be driven by MHD turbulence via the magneto-rotational instability (MRI). The dynamics of solid bodies embedded in such discs (dust…

Earth and Planetary Astrophysics · Physics 2015-05-19 Richard P. Nelson , Oliver Gressel

During the last decade it has become evident that the magnetorotational instability is at the heart of the enhanced angular momentum transport in weakly magnetized accretion disks around neutron stars and black holes. In this paper, we…

Astrophysics · Physics 2009-11-10 Martin E. Pessah , Dimitrios Psaltis

In Keplerian accretion disks, turbulence and magnetic fields may be jointly excited through a subcritical dynamo process involving the magnetorotational instability (MRI). High-resolution simulations exhibit a tendency towards statistical…

High Energy Astrophysical Phenomena · Physics 2017-02-08 A. Riols , F. Rincon , C. Cossu , G. Lesur , G. I. Ogilvie , P-Y. Longaretti

The magnetorotational instability is thought to be responsible for the generation of magnetohydrodynamic turbulence that leads to enhanced outward angular momentum transport in accretion discs. Here, we present the first formal analytical…

Astrophysics · Physics 2009-11-11 Martin E. Pessah , Chi-kwan Chan , Dimitrios Psaltis

A certain appeal to the alpha model for turbulence and related viscosity in accretion disks was that one scales the Reynolds stresses simply on the thermal pressure, assuming that turbulence driven by a certain mechanism will attain a…

Earth and Planetary Astrophysics · Physics 2021-09-22 Natascha Manger , Thomas Pfeil , Hubert Klahr

Accretion disks around compact stars are formed due to turbulence driven by magnetorotational instability. Despite over thirty years of numerous computational studies on magnetorotational turbulence, the properties of fluctuations in the…

Plasma Physics · Physics 2024-08-30 Yohei Kawazura , Shigeo S. Kimura

We use the mean-field dynamo equations to show that an incoherent alpha effect in mirror-symmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple…

Astrophysics · Physics 2015-06-24 Ethan T. Vishniac , Axel Brandenburg

Turbulent plane-Couette flow suspended with finite-size spheroidal particles is studied using fully particle-resolved direct numerical simulations. The effects of particle aspect ratio on turbulent arguments and particle statistics are…

Fluid Dynamics · Physics 2023-11-06 Cheng Wang , Linfeng Jiang , Chao Sun

We analyze the spectral properties of driven, supersonic compressible magnetohydrodynamic (MHD) turbulence obtained via high-resolution numerical experiments, for application to understanding the dynamics of giant molecular clouds. Via…

Astrophysics · Physics 2009-11-07 Jason G. Vestuto , Eve C. Ostriker , James M. Stone
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