Parallel, grid-adaptive approaches for relativistic hydro and magnetohydrodynamics

Keppens, Rony; Méliani, Z.; Marle, Allard Jan van; Delmont, Peter; Vlasis, Alkis; Holst, B. van der

doi:10.1016/j.jcp.2011.01.020

Cited by 274 publications

(271 citation statements)

References 81 publications

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“…The evolution of the fluid is calculated with MPI-AMRVAC (Message Passing Interface-Adaptive Mesh Refinement Versatile Advection Code) presented in Keppens et al (2012). We used the Lax-Friedrich scheme (see Tóth 1996) with a Koren limiter (Koren 1993).…”

Section: Methodsmentioning

confidence: 99%

Dust-trapping Rossby vortices in protoplanetary disks

Méheut¹,

Méliani²,

Varnière³

et al. 2012

A&A

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Context. One of the most challenging steps in planet formation theory is the one leading to the formation of planetesimals of kilometre size. A promising scenario involves the existence of vortices able to concentrate a large amount of dust and grains in their centres. Up to now this scenario has mostly been studied in 2D razor thin disks. A 3D study including, simultaneously, the formation and resulting dust concentration of the vortices with vertical settling, is still missing. Aims. The Rossby wave instability self-consistently forms 3D vortices, which have the unique quality of presenting a large-scale vertical velocity in their centre. Here we aim to study how this newly discovered effect can alter the dynamic evolution of the dust. Methods. We performed global 3D simulations of the RWI in a radially and vertically stratified disk using the code MPI-AMRVAC. After the growth phase of the instability, the gas and solid phases are modelled by a bi-fluid approach, where the dust is considered as a fluid without pressure. Both the drag force of the gas on the dust and the back reaction of the dust on the gas are included. Multiple grain sizes from 1 mm to 5 cm are used with a constant density distribution. Results. We obtain in a short timescale a high concentration of the largest grains in the vortices. Indeed, in 3 rotations the dust-to-gas density ratio grows from 10 −2 to unity leading to a concentration of mass up to that of Mars in one vortex. The presence of the radial drift is also at the origin of a dust pile-up at the radius of the vortices. Lastly, the vertical velocity of the gas in the vortex causes the sedimentation process to be reversed, the mm size dust is lifted and higher concentrations are obtained in the upper layer than in the midplane. Conclusions. The Rossby wave instability is a promising mechanism for planetesimal formation, and the results presented here can be of particular interest in the context of future observations of protoplanetary disks.

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Section: Methodsmentioning

confidence: 99%

Dust-trapping Rossby vortices in protoplanetary disks

Méheut¹,

Méliani²,

Varnière³

et al. 2012

A&A

Self Cite

112

108

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“…This means that any dynamics occurring within the MHD simulation are purely due to the stress developed in the GNLFFF simulation before the data is transferred into the MHD simulation. We use the AMRVAC code mainly developed at the KU Leuven to run the simulations (Keppens et al 2012). The code solves the MHD equations in their conservative form and we make use of the magnetic field splitting technique (Powell et al 1999) and consider…”

Section: Armvac Codementioning

confidence: 99%

“…We will first use the global non-linear force-free field (GNLFFF) model of Mackay & van Ballegooijen (2006a) which neglects the role of the plasma to consider the formation of the flux rope in the zero-β, quasi-static approximation. Once the flux rope forms and is about to erupt, we apply a full MHD approach, through using the stressed magnetic field configuration from the GNLFFF model as an initial condition in MHD simulations using the AMRVAC code (Keppens et al 2012). With this we can accurately describe the full life span of the evolution of a flux rope from its slow generation to its rapid ejection.…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic simulations of the ejection of a magnetic flux rope

Pagano

Mackay

Poedts

2013

A&A

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Context. Coronal mass ejections (CME's) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the flux rope ejection model. In this model, magnetic flux ropes form slowly over time periods of days to weeks. They then lose equilibrium and are ejected from the solar corona over a few hours. The contrasting time scales of formation and ejection pose a serious problem for numerical simulations. Aims. We simulate the whole life span of a flux rope from slow formation to rapid ejection and investigate whether magnetic flux ropes formed from a continuous magnetic field distribution, during a quasi-static evolution, can erupt to produce a CME. Methods. To model the full life span of magnetic flux ropes we couple two models. The global non-linear force-free field (GNLFFF) evolution model is used to follow the quasi-static formation of a flux rope. The MHD code ARMVAC is used to simulate the production of a CME through the loss of equilibrium and ejection of this flux rope. Results. We show that the two distinct models may be successfully coupled and that the flux rope is ejected out of our simulation box, where the outer boundary is placed at 2.5 R . The plasma expelled during the flux rope ejection travels outward at a speed of 100 km s −1 , which is consistent with the observed speed of CMEs in the low corona. Conclusions. Our work shows that flux ropes formed in the GNLFFF can lead to the ejection of a mass loaded magnetic flux rope in full MHD simulations. Coupling the two distinct models opens up a new avenue of research to investigate phenomena where different phases of their evolution occur on drastically different time scales.

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“…The simulations also show if dust grains are good tracers for the gas-driven dynamics in the bow shock. The hydrodynamical computations were done using MPI-AMRVAC code (Keppens et al 2012;van Marle et al 2011). More details Rodgers & Glassgold (1991) on the numerical method and initial conditions are given in Appendix E. The simulation was run for five different situations, using variations of a basic model to explore several aspects of the bow shock morphology and its dependence on the properties of the wind and the ambient medium.…”

Section: Constraints From Hydrodynamical Modellingmentioning

confidence: 99%

“…For the simulations the MPI-AMRVAC hydrodynamics code (Keppens et al 2012) was used. For a comparison to similar work, we refer to van Marle et al (2011).…”

Section: Appendix A: Previous Images Of the Bow Shock Around Betelgeusementioning

confidence: 99%

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

Decin

Cox

Royer

et al. 2012

A&A

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Context. The interaction between stellar winds and the interstellar medium (ISM) can create complex bow shocks. The photometers on board the Herschel Space Observatory are ideally suited to studying the morphologies of these bow shocks. Aims. We aim to study the circumstellar environment and wind-ISM interaction of the nearest red supergiant, Betelgeuse. Methods. Herschel PACS images at 70, 100, and 160 μm and SPIRE images at 250, 350, and 500 μm were obtained by scanning the region around Betelgeuse. These data were complemented with ultraviolet GALEX data, near-infrared WISE data, and radio 21 cm GALFA-HI data. The observational properties of the bow shock structure were deduced from the data and compared with hydrodynamical simulations. Results. The infrared Herschel images of the environment around Betelgeuse are spectacular, showing the occurrence of multiple arcs at ∼6-7 from the central target and the presence of a linear bar at ∼9 . Remarkably, no large-scale instabilities are seen in the outer arcs and linear bar. The dust temperature in the outer arcs varies between 40 and 140 K, with the linear bar having the same colour temperature as the arcs. The inner envelope shows clear evidence of a non-homogeneous clumpy structure (beyond 15 ), probably related to the giant convection cells of the outer atmosphere. The non-homogeneous distribution of the material even persists until the collision with the ISM. A strong variation in brightness of the inner clumps at a radius of ∼2 suggests a drastic change in mean gas and dust density ∼32 000 yr ago. Using hydrodynamical simulations, we try to explain the observed morphology of the bow shock around Betelgeuse. Conclusions. Different hypotheses, based on observational and theoretical constraints, are formulated to explain the origin of the multiple arcs and the linear bar and the fact that no large-scale instabilities are visible in the bow shock region. We infer that the two main ingredients for explaining these phenomena are a non-homogeneous mass-loss process and the influence of the Galactic magnetic field. The hydrodynamical simulations show that a warm interstellar medium, reflecting a warm neutral or partially ionized medium, or a higher temperature in the shocked wind also prevent the growth of strong instabilities. The linear bar is probably an interstellar structure illuminated by Betelgeuse itself.

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Parallel, grid-adaptive approaches for relativistic hydro and magnetohydrodynamics

Cited by 274 publications

References 81 publications

Dust-trapping Rossby vortices in protoplanetary disks

Dust-trapping Rossby vortices in protoplanetary disks

Magnetohydrodynamic simulations of the ejection of a magnetic flux rope

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

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