Prace Call: 17th
ID: 2018184398, Leader: Turlough Downes
Affiliation: Dublin City University, IE
Research Field: Universe Sciences
Collaborators: Donna Rodgers-Lee University of Hertfordshire UK , Antonella Natta Dublin Institute for Advanced Studies IE
Resource Awarded: 60 Mil. core hours on Marconi - KNL
Virtually all low and intermediate mass stars (such as our Sun) form by accreting material from a surrounding molecular cloud through an accretion disk. It is in these disks, so-called protoplanetary disks, that planets form. Observations indicate that many of these disks are in Keplerian rotation, implying a balance between the centrifugal and gravitational forces. There is a fundamental mystery surrounding the issue of how material can move inward through a protoplanetary disk and onto the young stellar object (YSO). As the material moves inward it must lose angular momentum rapidly - if this did not happen the material could not move in toward the forming star at the observed rates and star formation would be extremely difficult. How, then, does the accreting material lose its angular momentum? One possibility is that an instability such as the magnetorotational instability (MRI) could produce turbulence in the disk which would, itself, create a highly effective viscosity. This viscosity would then act to transfer angular momentum from material at a particular point in the disk to material further out in the disk, thereby enabling accretion. Protoplanetary disks, though, are complex systems comprised of many chemical species and dust grains some of which are charged (and interact with magnetic fields), and some of which are neutral: in short, it is a multifluid system made up of various charged and neutral fluids which move under differing equations of motion. To gain a proper understanding of how turbulence in accretion disks behaves and how it can be generated we must move towards full multifluid modeling. With such modeling we are able to self-consistently investigate possible regions of dust concentrations (of relevance to planet formation) and the creation of disk "gaps" by the action of MRI. This is particularly interesting because current observations of these protoplanetary disks focus on both the gas and the dust in the disks. The dust is not distributed in the same way as the gas, and this project will model the dynamics of the dust self-consistently including, for the first time, the effect of magnetic fields thereby allowing us to make a direct link between disk simulations and dust observations. We will use the the state-of-the-art, massively parallel multi-fluid magnetohydrodynamic code HYDRA, coupled with the power of the MareNostrum4 system, to perform full 3D modeling of the dynamics of these proto-planetary disks including charged dust dynamics. The observational signatures will be derived a posteriori from the simulations using a dust radiative transfer code such as the open-source HYPERION code. HYDRA is well-tested and proven both from the point of view of the published physical results it has generated and in terms of its scalability it has been shown to perform extremely well using 16384 cores on the MareNostrum4 system.