Grand Challenges in Protoplanetary Disc Modelling

Haworth, Thomas J.; Ilee, J. D.; Forgan, Duncan; Facchini, Stefano; Price, Daniel J.; Boneberg, Dominika M.; Booth, Richard A; Clarke, C. J.; Gonzalez, Jean-François; Hutchison, Mark; Kamp, I.; Laibe, Guillaume; Lyra, Wladimir; Meru, Farzana; Mohanty, Subhanjoy; Panić, Olja; Rice, Ken; Suzuki, Takeru; Teague, Richard; Walsh, Catherine; Woitke, P.

doi:10.1017/pasa.2016.45

Cited by 69 publications

(34 citation statements)

References 293 publications

(423 reference statements)

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“…There is now overwhelming evidence that planets form from discs of material around young stars (for reviews see e.g. Williams & Cieza 2011;Andrews 2015;Owen 2016;Sicilia-Aguilar et al 2016;Haworth et al 2016a;Ercolano & Pascucci 2017). The vast majority of studies of disc evolution and planet formation consider the young star-disc in isolation and such approaches are proving very effective at understanding the myriad physical processes that take place in planet-forming discs.…”

Section: Introductionmentioning

confidence: 99%

The first multidimensional view of mass loss from externally FUV irradiated protoplanetary discs

Haworth

Clarke

2019

Monthly Notices of the Royal Astronomical Society

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Computing the flow from externally FUV irradiated protoplanetary discs requires solving complicated and expensive photodissociation physics iteratively in conjunction with hydrodynamics. Previous studies have therefore been limited to 1D models of this process. In this paper we compare 2D-axisymmetric models of externally photoevaporating discs with their 1D analogues, finding that mass loss rates are consistent to within a factor four. The mass loss rates in 2D are higher, in part because half of the mass loss comes from the disc surface (which 1D models neglect). 1D mass loss rates used as the basis for disc viscous evolutionary calculations are hence expected to be conservative. We study the anatomy of externally driven winds including the streamline morphology, kinematic, thermal and chemical structure. A key difference between the 1D and 2D models is in the chemical abundances. For instance in the 2D models CO can be dissociated at smaller radial distances from the disc outer edge than in 1D calculations because gas is photodissociated by radiation along trajectories that are assumed infinitely optically thick in 1D models. Multidimensional models will hence be critical for predicting observable signatures of environmentally photoevaporating protoplanetary discs.

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Section: Introductionmentioning

confidence: 99%

The first multidimensional view of mass loss from externally FUV irradiated protoplanetary discs

Haworth

Clarke

2019

Monthly Notices of the Royal Astronomical Society

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“…The condition (2) is violated with our adopted grid computational method (h = 10c s t stop ), but it is possible to closely approach the exact solution by reducing the time step. Figure 2 presents the analogous results for the scheme (19)- (21) for various CF L values. The dot-dashed curves in the upper panels show the gas velocity that the medium would have if the dust exerted no influence on the gas dynamics.…”

Section: Numerical Solution Of the Dustywave Problemmentioning

confidence: 97%

“…The propagation of the sound wave is obtained with acceptable accuracy for both a stiffly coupled and weakly coupled medium. Thus, the condition (2) is not necessary for the piecewise-parabolic advection (PPA) method applied in conjunction with the scheme (19)- (21) or (23)- (24). It is clear that both of the approaches (19)-(21) and (23)-(24) enable the use of a time step determined from the Courant condition (37) for a two-phase medium without additional reduction (15) due to the appearance of the "short" time t stop .…”

Section: Numerical Solution Of the Dustywave Problemmentioning

confidence: 99%

Analysis of Numerical Algorithms for Computing Rapid Momentum Transfers between the Gas and Dust in Simulations of Circumstellar Disks

2018

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Approaches used in modern numerical simulations of the dynamics of dust and gas in circumstellar disks are tested. The gas and dust are treated like interpenetrating continuous media that can exchange momentum. A stiff coupling between the gas and dust phases is typical for such disks, with the dust stopping time much less than the characteristic dynamical time scale. This imposes high demands on the methods used to simulate the dust dynamics. A grid, piecewise-parabolic method is used as the basic algorithm for solving the gas-dynamical equations. Numerical solutions obtained using various methods to compute the momentum exchanges are presented for the case of monodisperse dust. Numerical solutions are obtained for shock tube problem and the propagation of sound waves in a gas-dust medium. The studied methods are compared in terms of their ability to model media with (a) an arbitrary (short or long) dust stopping time, and (b) an arbitrary dust concentration in the gas (varying the dust to gas mass ratio from 0.01 to 1). A method for computing the momentum exchange with infinite-order accuracy in time is identified, which makes it possible to satisfy the conditions (a) and (b) with minimal computational costs. A first-order method that shows similar results in the test computations is also presented. It is shown that the proposed first-order method for monodisperse dust can be extended to a regime when the dust is polydisperse; i.e., a regime represented by several fractions with different stopping times. Formulas for computing the gas and dust velocities for polydisperse dust with each fraction exchanging momentum with the gas are presented. snyt@catalysis.ru 4 The commonly used term for this ratio, the "stopping time", can lead to confusion, since, in the approximation considered here, a particle does not acquire the velocity of the gas, but instead a constant velocity relative to the gas velocity.

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“…where r 0 = 20 AU, St = 2 × 10 −3 . According to (7) under the conditions of a massive disk described in Section 2, this stopping time corresponds to an initial radius for the bodies of 2 − 3 mm. The migration of bodies in the inner region of the disk in a regime in which the stopping time remains constant implies that the radius of solid-phase particles grows in accordance with a law that depends on the surface density and radius.…”

Section: Migration Of a Ringmentioning

confidence: 99%

Analysis of Methods for Computing the Trajectories of Dust Particles in a Gas–Dust Circumstellar Disk

2017

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A systematic analysis of methods for computing the trajectories of solid-phase particles applied in modern astrophysics codes designed for modeling gas-dust circumstellar disks has been carried out for the first time. The motion of grains whose velocities are determined mainly by the gas drag, that is, for which the stopping time or relaxation time for the velocity of the dust to the velocity of the gas tstop is less than or comparable to the rotation period, are considered. The methods are analyzed from the point of view of their suitability for computing the motions of small bodies, including dust grains less than 1 µm in size, which are strongly coupled to the gas. Two test problems are with analytical solutions. Fast first order accurate methods that make it possible to avoid additional restrictions on the time step size τ due to gas drag in computations of the motion of grains of any size are presented. For the conditions of a circumstellar disk, the error in the velocity computations obtained when using some stable methods becomes unacceptably large when the time step size is τ > tstop. For the radial migration of bodies that exhibit drifts along nearly Keplerian orbits, an asymptotic approximation, sometimes called the short friction time approximation or drift flux model, gives a relative error for the radial-velocity computations equals to St 2 where St is the Stokes number, the ratio of the stopping time of the body to some fraction of the rotation period (dynamical time scale) in the disk.

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Grand Challenges in Protoplanetary Disc Modelling

Cited by 69 publications

References 293 publications

The first multidimensional view of mass loss from externally FUV irradiated protoplanetary discs

The first multidimensional view of mass loss from externally FUV irradiated protoplanetary discs

Analysis of Numerical Algorithms for Computing Rapid Momentum Transfers between the Gas and Dust in Simulations of Circumstellar Disks

Analysis of Methods for Computing the Trajectories of Dust Particles in a Gas–Dust Circumstellar Disk

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