Magnetic viscosity by localized shear flow instability in magnetized accretion disks

Matsumoto, Ryoji; Tajima, T.

doi:10.1086/175739

Cited by 155 publications

(144 citation statements)

References 13 publications

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“…There is vast literature studying this mechanism in local shearing box simulations with an ideal MHD description (Brandenburg et al 1995;Hawley et al 1995Hawley et al , 1996Matsumoto & Tajima 1995;Stone et al 1996;Sano et al 2004). …”

Section: Introductionmentioning

confidence: 99%

Turbulence and Steady Flows in Three-Dimensional Global Stratified Magnetohydrodynamic Simulations of Accretion Disks

Flock

Dzyurkevich

Klahr

et al. 2011

ApJ

127

177

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We present full 2π global 3-D stratified MHD simulations of accretion disks. We interpret our results in the context of proto-planetary disks. We investigate the turbulence driven by the magneto-rotational instability (MRI) using the PLUTO Godunov code in spherical coordinates with the accurate and robust HLLD Riemann solver. We follow the turbulence for more than 1500 orbits at the innermost radius of the domain to measure the overall strength of turbulent motions and the detailed accretion flow pattern.We find that regions within two scale heights of the midplane have a turbulent Mach number of about 0.1 and a magnetic pressure two to three orders of magnitude less than the gas pressure, while outside three scale heights the magnetic pressure equals or exceeds the gas pressure and the turbulence is transonic, leading to large density fluctuations. The strongest large-scale density disturbances are spiral density waves, and the strongest of these waves has m = 5. No clear meridional circulation appears in the calculations because fluctuating radial pressure gradients lead to changes in the orbital frequency, comparable in importance to the stress gradients that drive the meridional flows in viscous models. The net mass flow rate is well-reproduced by a viscous model using the mean stress distribution taken from the MHD calculation.The strength of the mean turbulent magnetic field is inversely proportional to the radius, so the fields are approximately force-free on the largest scales. Consequently the accretion stress falls off as the inverse square of the radius.

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Section: Introductionmentioning

confidence: 99%

Turbulence and Steady Flows in Three-Dimensional Global Stratified Magnetohydrodynamic Simulations of Accretion Disks

Flock

Dzyurkevich

Klahr

et al. 2011

ApJ

127

177

View full text Add to dashboard Cite

show abstract

“…The magnetic shear instability can be completely suppressed by a sufficiently strong magnetic field (see Urpin 1996;Kitchatinov & Rüdiger 1997). Simulations of MRI in disks (Hawley et al 1995;Matsumoto & Tajima 1995;Brandenburg et al 1995;Torkelsson et al 1996;Arlt & Rüdiger 2001) show that the turbulence generated strongly enhances angular momentum transport.…”

Section: Introductionmentioning

confidence: 99%

The stability of magnetized protostellar disks with the Hall effect and buoyancy

Урпин

Rüdiger²

2005

A&A

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Abstract. The stability properties of cool protostellar disks are examined by use of the dispersion relation taking into account the Hall effect and buoyancy. Depending on the conditions, different types of instabilities can arise in different regions of the disk. In very low-ionized regions the instability associated with baroclinic effects of buoyancy is likely most efficient. The shearHall instability will be responsible for destabilization of regions with a weak magnetic field (parallel to the rotation axis) and with low conductivity (Λ < a e , Λ = σB 2 /ρΩ Elsässer number, a e magnetization parameter of electrons). The magnetorotational instability modified by buoyancy should be the main destabilizing factor in regions with sufficiently strong magnetic fields and/or high conductivity (Λ > a e ). For a magnetic field amplitude of 1 Gauss the transition between both the regions happens at approximately 1 AU.

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“…Many classical studies of the magneto-rotational instability (MRI) were conducted with the ideal MHD approach and the local shearing box approximation (Brandenburg et al 1995;Hawley et al , 1996Matsumoto & Tajima 1995;Stone et al 1996;Sano et al 2004), partly reviewed in Balbus & Hawley (1998). However, recent developments have shown that critical questions about turbulence in accretion disks can only be addressed in global simulations (Fromang & Nelson 2006;Lyra et al 2008;Fromang & Nelson 2009;Fromang & Papaloizou 2007;Davis et al 2010).…”

Section: Introductionmentioning

confidence: 99%

High-order Godunov schemes for global 3D MHD simulations of accretion disks

Flock¹,

Dzyurkevich²,

Klahr³

et al. 2010

A&A

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We assess the suitability of various numerical MHD algorithms for astrophysical accretion disk simulations with the PLUTO code. The well-studied linear growth of the magneto-rotational instability is used as the benchmark test for a comparison between the implementations within PLUTO and against the ZeusMP code. The results demonstrate the importance of using an upwind reconstruction of the electro-motive force (EMF) in the context of a constrained transport scheme, which is consistent with plane-parallel, grid-aligned flows. In contrast, constructing the EMF from the simple average of the Godunov fluxes leads to a numerical instability and the unphysical growth of the magnetic energy. We compare the results from 3D global calculations using different MHD methods against the analytical solution for the linear growth of the MRI, and discuss the effect of numerical dissipation. The comparison identifies a robust and accurate code configuration that is vital for realistic modeling of accretion disk processes.

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Magnetic viscosity by localized shear flow instability in magnetized accretion disks

Cited by 155 publications

References 13 publications

Turbulence and Steady Flows in Three-Dimensional Global Stratified Magnetohydrodynamic Simulations of Accretion Disks

Turbulence and Steady Flows in Three-Dimensional Global Stratified Magnetohydrodynamic Simulations of Accretion Disks

The stability of magnetized protostellar disks with the Hall effect and buoyancy

High-order Godunov schemes for global 3D MHD simulations of accretion disks

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