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We present long-term (~10^4 M) axisymmetric simulations of differentially rotating, magnetized neutron stars in the slow-rotation, weak magnetic field limit using a perturbative metric evolution technique. Although this approach yields…

Astrophysics · Physics 2009-11-11 Zachariah B. Etienne , Yuk Tung Liu , Stuart L. Shapiro

Magneto-rotational instability (MRI) is an important instability mechanism for rotating flows with magnetic fields. In particular, when the strength of the magnetic field tends to zero, the stability criterion for rotating flows is…

Analysis of PDEs · Mathematics 2024-10-28 Zhiwu Lin , Yucong Wang , Wenpei Wu

The Kelvin-Helmholtz instability serves as a simple, well-defined setup for assessing the accuracy of different numerical methods for solving the equations of hydrodynamics. We use it to extend our previous analysis of the convergence and…

Instrumentation and Methods for Astrophysics · Physics 2020-12-09 Martin Obergaulinger , Miguel-Ángel Aloy

Based on the characteristics of the magnetorotational instability (MRI) and the MRI-driven turbulence, we construct a steady model for a geometrically thin disk using "non-standard" $\alpha$-prescription. The efficiency of the angular…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Hiroyuki R. Takahashi , Youhei Masada

Variable density incompressible flows are governed by parabolic equations. The artificial compressibility method makes these equations hyperbolic-type, which means that they can be solved using techniques developed for compressible flows,…

Fluid Dynamics · Physics 2022-03-09 Shannon Leakey , Vassilis Glenis , Caspar J. M. Hewett

Electrostatic gyrokinetic instabilities and turbulence in the Wendelstein 7-X stellarator are studied. Particular attention is paid to the ion-temperature-gradient (ITG) instability and its character close to marginal stability…

Plasma Physics · Physics 2024-07-25 L. Podavini , A. Zocco , J. M. García-Regaña , M. Barnes , F. I. Parra , A. Mishchenko , P. Helander

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

Turbulent transport is known to limit the plasma confinement of present-day optimized stellarators. To address this issue, a novel method to strongly suppress turbulence in such devices is proposed, namely the resonant wave-particle…

Plasma Physics · Physics 2020-09-09 Alessandro Di Siena , Alejandro Banon Navarro , Frank Jenko

The magnetorotational instability (MRI) is considered to be one of the most powerful sources of turbulence in hydrodynamically stable quasi-Keplerian flows, such as those governing accretion disk flows. Although the linear stability of…

Fluid Dynamics · Physics 2017-11-21 A. Guseva , R. Hollerbach , A. P. Willis , M. Avila

Numerical simulations of the magnetorotational instability (MRI) with zero initial net flux in a non-stratified isothermal cubic domain are used to demonstrate the importance of magnetic boundary conditions.In fully periodic systems the…

High Energy Astrophysical Phenomena · Physics 2011-07-08 Petri J. Käpylä , Maarit J. Korpi

The recurrent outbursts that characterise low-mass binary systems reflect thermal state changes in their associated accretion discs. The observed outbursts are connected to the strong variation in disc opacity as hydrogen ionises near 5000…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Henrik N. Latter , John C. B. Papaloizou

The magnetorotational instability (MRI) occurs when a weak magnetic field destabilises a rotating, electrically conducting fluid with inwardly increasing angular velocity. The MRI is essential to astrophysical disk theory where the shear is…

We investigate three-dimensional turbulence in a stably stratified fluid driven by a vertically sheared Kolmogorov flow using direct numerical simulations of the Boussinesq equations. As stratification increases, mean profiles evolve toward…

Fluid Dynamics · Physics 2025-12-16 Alessandro Sozza , Andrea Maffioli

The magnetorotational instability (MRI) is believed to be responsible for most of the angular momentum transport in accretion discs. However, molecular dissipation processes may drastically change the efficiency of MRI turbulence in…

Earth and Planetary Astrophysics · Physics 2015-05-20 Geoffroy Lesur , Pierre-Yves Longaretti

The magnetorotational instability (MRI) is a fundamental mechanism determining the macroscopic dynamics of astrophysical accretion disks. In collisionless accretion flows around supermassive black holes, MRI-driven plasma turbulence…

High Energy Astrophysical Phenomena · Physics 2022-10-26 Fabio Bacchini , Lev Arzamasskiy , Vladimir Zhdankin , Gregory R. Werner , Mitchell C. Begelman , Dmitri A. Uzdensky

We study the saturation near threshold of the axisymmetric magnetorotational instability (MRI) of a viscous, resistive, incompressible fluid in a thin-gap Taylor-Couette configuration. A vertical magnetic field, Keplerian shear and no-slip,…

Astrophysics · Physics 2009-11-13 O. M. Umurhan , O. Regev , K. Menou

The magnetorotational instability is thought to play an important role in enabling accretion in sufficiently ionized astrophysical disks. The rate at which MRI-driven turbulence transports angular momentum is related to both the strength of…

Solar and Stellar Astrophysics · Physics 2015-10-26 Gareth C. Murphy , Martin E. Pessah

We study the chaotic properties of a turbulent conducting fluid using direct numerical simulation in the Eulerian frame. The maximal Lyapunov exponent is measured for simulations with varying Reynolds number and magnetic Prandtl number. We…

Fluid Dynamics · Physics 2019-05-22 Richard Ho , Arjun Berera , Daniel Clark

The dynamo driven by the magnetorotational instability (MRI) is believed to play an important role in the dynamics of accretion discs and may also explain the origin of the extreme magnetic fields present in magnetars. Its saturation level…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Jerome Guilet , Alexis Reboul-Salze , Raphael Raynaud , Matteo Bugli , Basile Gallet

Though usually treated in isolation, the magnetorotational and gravitational instabilities (MRI and GI) may coincide at certain radii and evolutionary stages of protoplanetary discs and active galactic nuclei. Their mutual interactions…

High Energy Astrophysical Phenomena · Physics 2017-12-27 A. Riols , H. Latter