Growth of the MRI in accretion discs - the influence of radiation transport

Flaig, Markus; Kissmann, R.; Kley, W.

doi:10.1111/j.1365-2966.2009.14496.x

Cited by 8 publications

(8 citation statements)

References 35 publications

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“…The first full radiation magneto-hydrodynamics (RMHD) of that problem were performed in local box simulations by Turner et al (2003) using a flux-limited diffusion (FLD) approach (Levermore & Pomraning 1981). Over the past few years, several accretion disc simulations have been performed using similar numerical schemes (Turner 2004;Hirose et al 2006;Blaes et al 2007;Krolik et al 2007;Flaig et al 2009) and have recently included irradiation heating (Hirose & Turner 2011). More sophisticated radiation hydrodynamics (RHD) methods, like the two-moment method (González et al 2007), are usually very time demanding because they require large matrix inversion.…”

Section: Introductionmentioning

confidence: 99%

Radiation magnetohydrodynamics in global simulations of protoplanetary discs

Flock

Fromang

González

et al. 2013

A&A

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Aims. Our aim is to study the thermal and dynamical evolution of protoplanetary discs in global simulations, including the physics of radiation transfer and magneto-hydrodynamic turbulence caused by the magneto-rotational instability. Methods. We have developed a radiative transfer method based on the flux-limited diffusion approximation that includes frequency dependent irradiation by the central star. This hybrid scheme is implemented in the PLUTO code. The focus of our implementation is on the performance of the radiative transfer method. Using an optimized Jacobi preconditioned BiCGSTAB solver, the radiative module is three times faster than the magneto-hydrodynamic step for the disc set-up we consider. We obtain weak scaling efficiencies of 70% up to 1024 cores. Results. We present the first global 3D radiation magneto-hydrodynamic simulations of a stratified protoplanetary disc. The disc model parameters were chosen to approximate those of the system AS 209 in the star-forming region Ophiuchus. Starting the simulation from a disc in radiative and hydrostatic equilibrium, the magneto-rotational instability quickly causes magneto-hydrodynamic turbulence and heating in the disc. We find that the turbulent properties are similar to that of recent locally isothermal global simulations of protoplanetary discs. For example, the rate of angular momentum transport α is a few times 10 −3 . For the disc parameters we use, turbulent dissipation heats the disc midplane and raises the temperature by about 15% compared to passive disc models. The vertical temperature profile shows no temperature peak at the midplane as in classical viscous disc models. A roughly flat vertical temperature profile establishes in the optically thick region of the disc close to the midplane. We reproduce the vertical temperature profile with viscous disc models for which the stress tensor vertical profile is flat in the bulk of the disc and vanishes in the disc corona. Conclusions. The present paper demonstrates for the first time that global radiation magneto-hydrodynamic simulations of turbulent protoplanetary discs are feasible with current computational facilities. This opens up the window to a wide range of studies of the dynamics of the inner parts of protoplanetary discs, for which there are significant observational constraints.

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Section: Introductionmentioning

confidence: 99%

Radiation magnetohydrodynamics in global simulations of protoplanetary discs

Flock

Fromang

González

et al. 2013

A&A

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“…Some first results in this direction apply the fluxlimited radiation diffusion approach in shearing-box calculations (Turner et al 2002;Turner 2004;Hirose et al 2006;Flaig et al 2009). The latter use a conservative, cell-centered finite volume scheme.…”

Section: Introductionmentioning

confidence: 99%

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

Flock¹,

Dzyurkevich²,

Klahr³

et al. 2010

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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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“…The saturation level of the MRI depends on numerical parameters such as the box size (Johansen, Youdin & Klahr 2009), the numerical resolution (Fromang & Papaloizou 2007; Davis, Stone & Pessah 2010; Simon, Hawley & Beckwith 2009; Shi, Krolik & Hirose 2010, hereafter SKH) and the numerical scheme (Balsara & Meyer 2010). There is also a dependence on the physical parameters viscosity and resistivity (Fromang et al 2007) and, to a lesser extent, also on the thermodynamics (Flaig, Kissmann & Kley 2009, hereafter FK2; see also Turner et al 2003). When doing MRI simulations, it is therefore very important to check the dependence of the results on numerical factors and also to include as much of the relevant physics as possible.…”

Section: Introductionmentioning

confidence: 99%

Vertical structure and turbulent saturation level in fully radiative protoplanetary disc models

Flaig

Kley

Kissmann

2010

Monthly Notices of the Royal Astronomical Society

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We investigate a massive ( g cm−2 at 1 au) protoplanetary disc model by means of 3D radiation magnetohydrodynamic simulations. The vertical structure of the disc is determined self‐consistently by a balance between turbulent heating caused by the magnetorotational turbulence and radiative cooling. Concerning the vertical structure, two different regions can be distinguished: a gas‐pressure‐dominated, optically thick mid‐plane region where most of the dissipation takes place, and a magnetically dominated, optically thin corona which is dominated by strong shocks. At the location of the photosphere, the turbulence is supersonic (), which is consistent with previous results obtained from the fitting of spectra of young stellar objects. It is known that the turbulent saturation level in simulations of MRI‐induced turbulence does depend on numerical factors such as the numerical resolution and the box size. However, by performing a suite of runs at different resolutions (using up to grid cells) and with varying box sizes (with up to 16 pressure scaleheights in the vertical direction), we find that both the saturation levels and the heating rates show a clear trend to converge once a sufficient resolution in the vertical direction has been achieved.

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Growth of the MRI in accretion discs - the influence of radiation transport

Cited by 8 publications

References 35 publications

Radiation magnetohydrodynamics in global simulations of protoplanetary discs

Radiation magnetohydrodynamics in global simulations of protoplanetary discs

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

Vertical structure and turbulent saturation level in fully radiative protoplanetary disc models

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