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Dynamic localized turbulent diffusion and its impact on the galactic ecosystem

Rennehan, Douglas and Babul, Arif and Hopkins, Philip F. and Davé, Romeel and Moa, Belaid (2019) Dynamic localized turbulent diffusion and its impact on the galactic ecosystem. Monthly Notices of the Royal Astronomical Society, 483 (3). pp. 3810-3831. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20190206-135711599

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Abstract

Modelling the turbulent diffusion of thermal energy, momentum, and metals is required in all galaxy evolution simulations due to the ubiquity of turbulence in galactic environments. The most commonly employed diffusion model, the Smagorinsky model, is known to be overdiffusive due to its strong dependence on the fluid velocity shear. We present a method for dynamically calculating a more accurate, locally appropriate, turbulent diffusivity: the dynamic localized Smagorinsky model. We investigate a set of standard astrophysically relevant hydrodynamical tests, and demonstrate that the dynamic model curbs overdiffusion in non-turbulent shear flows and improves the density contrast in our driven turbulence experiments. In galactic discs, we find that the dynamic model maintains the stability of the disc by preventing excessive angular momentum transport, and increases the metal-mixing time-scale in the interstellar medium. In both our isolated Milky Way-like galaxies and cosmological simulations, we find that the interstellar and circumgalactic media are particularly sensitive to the treatment of turbulent diffusion. We also examined the global gas enrichment fractions in our cosmological simulations, to gauge the potential effect on the formation sites and population statistics of Population III stars and supermassive black holes, since they are theorized to be sensitive to the metallicity of the gas out of which they form. The dynamic model is, however, not for galaxy evolution studies only. It can be applied to all astrophysical hydrodynamics simulations, including those modelling stellar interiors, planetary formation, and star formation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/sty3376DOIArticle
https://arxiv.org/abs/1807.11509arXivDiscussion Paper
ORCID:
AuthorORCID
Rennehan, Douglas0000-0002-1619-8555
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2018 December 7. Received 2018 November 27; in original form 2018 July 30. This research was enabled in part by support provided by WestGrid and Compute/Calcul Canada. DR and AB acknowledge support from NSERC (Canada) through the Discovery Grant program. DR thanks the organizers of the Computing the Universe: At the Intersection of Computer Science and Cosmology conference in Oaxaca, Mexico for an invited talk, and also James Wadsley and Andrey Kravtsov for their recommendations at the conference that led to the further refinement of this research project. DR also thanks Valentin Perret for the DICE code, and Fabrice Durier, Ondrea Clarkson, Austin Davis, and Maan Hani for many useful discussions during the course of this research. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NSF Collaborative Research Grant #1715847 and CAREER grant #1455342, and NASA grants NNX15AT06G, JPL 1589742, 17-ATP17-0214. We would also especially like to thank our referee, Wolfram Schmidt, for his contributions in improving the final version of this study.
Group:TAPIR
Funders:
Funding AgencyGrant Number
WestGridUNSPECIFIED
Compute CanadaUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
NSFAST-1715847
NSFAST-1455342
NASANNX15AT06G
JPL1589742
JPL17-ATP17-0214
Subject Keywords:diffusion, hydrodynamics, turbulence, methods: numerical, galaxies: intergalactic medium, galaxies: ISM
Record Number:CaltechAUTHORS:20190206-135711599
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190206-135711599
Official Citation:Douglas Rennehan, Arif Babul, Philip F Hopkins, Romeel Davé, Belaid Moa; Dynamic localized turbulent diffusion and its impact on the galactic ecosystem, Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, 1 March 2019, Pages 3810–3831, https://doi.org/10.1093/mnras/sty3376
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92742
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:07 Feb 2019 15:43
Last Modified:07 Feb 2019 15:43

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