Anisotropic hydrodynamic turbulence in accretion disks

Stoll, Moritz H. R.; Kley, W.; Picogna, Giovanni

doi:10.1051/0004-6361/201630226

Cited by 54 publications

(64 citation statements)

References 14 publications

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“…We again average over the radial and azimuthal domain of the simulation and over 200 snapshots taken between 500 and 700 local orbits. We find radial mass inflow for all models in the midplane, which aligns with the findings of Stoll, Kley & Picogna (2017), who find the same flow reversal applying an anisotropic viscosity model with a heightened z-viscosity component. Therefore, although there is only small to no outward radial angular momentum transport present in the midplane from the VSI, mass can be accreted efficiently.…”

Section: Transport Propertiessupporting

confidence: 89%

Vortex formation and survival in protoplanetary discs subject to vertical shear instability

Manger

Klahr

2018

Monthly Notices of the Royal Astronomical Society

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Several protoplanetary disks observed by ALMA show dust concentrations consistent with particle trapping in giant vortices. The formation and survival of vortices is of major importance for planet formation, because vortices act as particle traps and are therefore preferred locations of planetesimal formation. Recent studies showed that the vertical shear instability (VSI) is capable of generating turbulence and small vortices in protoplanetary disks that have the proper radial and vertical stratification and thermally relax on sufficiently short time scales. But the effect of the azimuthal extend of the disk is often neglected as the disks azimuth is limited to ∆φ ≤ π/2. We aim to investigate the influence of the azimuthal extent of the disk on the longterm evolution of a protoplanetary disk and the possibility of large vortices forming. To this end, we perform 3-dimensional simulations for up to 1000 local orbits using different values of ∆φ = π/2 to 2π for VSI in disks with a prescribed radial density and temperature gradient cooling on short timescales. We find the VSI capable of forming large vortices which can exist at least several hundred orbits in simulations covering a disk with ∆φ ≥ π. This suggests the VSI to be capable to form vortices or at least to trigger vortex formation via a secondary instability, e.g. Rossby Wave Instability or Kelvin Helmholtz Instability.

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Section: Transport Propertiessupporting

confidence: 89%

Vortex formation and survival in protoplanetary discs subject to vertical shear instability

Manger

Klahr

2018

Monthly Notices of the Royal Astronomical Society

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“…The turbulent velocity in the radial direction is significantly less than the one in the vertical direction in the scenario SIafterVSI. This is consistent with Stoll & Kley (2016) and Stoll et al (2017) showing that the vertical shear instability drives anisotropic turbulence. On the other hand, in the scenario SIwhileVSI the radial and the vertical Mach number are comparable near and in the mid-plane.…”

Section: Source Of Turbulencesupporting

confidence: 90%

The coexistence of the streaming instability and the vertical shear instability in protoplanetary disks

Schäfer

Johansen²,

Banerjee

2020

A&A

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The streaming instability is a leading candidate mechanism to explain the formation of planetesimals. Yet, the role of this instability in the driving of turbulence in protoplanetary disks, given its fundamental nature as a linear hydrodynamical instability, has so far not been investigated in detail. We study the turbulence that is induced by the streaming instability as well as its interaction with the vertical shear instability. For this purpose, we employ the FLASH Code to conduct two-dimensional axisymmetric global disk simulations spanning radii from 1 au to 100 au, including the mutual drag between gas and dust as well as the radial and vertical stellar gravity. If the streaming instability and the vertical shear instability start their growth at the same time, we find the turbulence in the dust mid-plane layer to be primarily driven by the streaming instability. It gives rise to vertical gas motions with a Mach number of up to ∼10 −2 . The dust scale height is set in a self-regulatory manner to about 1% of the gas scale height. In contrast, if the vertical shear instability is allowed to saturate before the dust is introduced into our simulations, then it continues to be the main source of the turbulence in the dust layer. The vertical shear instability induces turbulence with a Mach number of ∼10 −1 and thus impedes dust sedimentation. Nonetheless, we find the vertical shear instability and the streaming instability in combination to lead to radial dust concentration in long-lived accumulations which are significantly denser than those formed by the streaming instability alone. Thus, the vertical shear instability may promote planetesimal formation by creating weak overdensities that act as seeds for the streaming instability.

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“…1 in Takeuchi & Lin 2002). In laminar viscous discs (contrary to discs with turbulence driven by magneto-rotational and vertical shear instabilities, see Flock et al 2011 andStoll et al 2017), the gas is therefore expected to flow outward at the disc midplane and inward in the disc upper layers, producing the so-called meridional circulation (Urpin 1984;Kley & Lin 1992;Philippov & Rafikov 2017). This motion can represent a natural way of driving global outward radial transport of dust particles and could explain the refractory inclusions in meteorites (Takeuchi & Lin 2002;Ciesla 2009;Hughes & Armitage 2010).…”

Section: Velocitiesmentioning

confidence: 99%

Gas and multispecies dust dynamics in viscous protoplanetary discs: the importance of the dust back-reaction

Dipierro

Laibe

Alexander

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study the dynamics of a viscous protoplanetary disc hosting a population of dust grains with a range of sizes. We compute steady-state solutions, and show that the radial motion of both the gas and the dust can deviate substantially from those for a single-size dust population. Although the aerodynamic drag from the dust on the gas is weaker than in the case where all grains are optimally coupled to the gas, the cumulative "back-reaction" of the dust particles can still alter the gas dynamics significantly. In typical protoplanetary discs, the net effect of the dust back-reaction decreases the gas accretion flow compared to the dust-free (viscous) case, even for dust-to-gas ratios of order 1%. In the outer disc, where dust grains are typically less strongly coupled to the gas and settle towards the midplane, the dust back-reaction can even drive outward gas flow. Moreover, the radial inward drift of large grains is reduced below the gas motion in the inner disc regions, while small dust grains follow the gas dynamics over all the disc extent. The resulting dust and gas dynamics can give rise to observable structures, such as gas and dust cavities. Our results show that the dust back-reaction can play a major role in both the dynamics and observational appearance of protoplanetary discs, and cannot be ignored in models of protoplanetary disc evolution.

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Anisotropic hydrodynamic turbulence in accretion disks

Cited by 54 publications

References 14 publications

Vortex formation and survival in protoplanetary discs subject to vertical shear instability

Vortex formation and survival in protoplanetary discs subject to vertical shear instability

The coexistence of the streaming instability and the vertical shear instability in protoplanetary disks

Gas and multispecies dust dynamics in viscous protoplanetary discs: the importance of the dust back-reaction

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