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Nonlinear Evolution of Instabilities Between Dust and Sound Waves

Moseley, Eric R. and Squire, Jonathan and Hopkins, Philip F. (2018) Nonlinear Evolution of Instabilities Between Dust and Sound Waves. . (Unpublished) http://resolver.caltech.edu/CaltechAUTHORS:20190206-105610955

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Abstract

We study the non-linear evolution of the acoustic 'Resonant Drag Instability' (RDI) using numerical simulations. The acoustic RDI is excited in a dust-gas mixture when dust grains stream through gas, interacting with sound waves to cause a linear instability. We study this process in a periodic box by accelerating neutral dust with an external driving force. The instability grows as predicted by linear theory, eventually breaking into turbulence and saturating. As in linear theory, the non-linear behavior is characterized by three regimes - high, intermediate, and low wavenumbers - the boundary between which is determined by the dust-gas coupling strength and the dust-to-gas mass ratio. The high and intermediate wavenumber regimes behave similarly to one another, with large dust-to-gas ratio fluctuations while the gas remains largely incompressible. The saturated state is highly anisotropic: dust is concentrated in filaments, jets, or plumes along the direction of acceleration, with turbulent vortex-like structures rapidly forming and dissipating in the perpendicular directions. The low-wavenumber regime exhibits large fluctuations in gas and dust density, but the dust and gas remain more strongly coupled in coherent 'fronts' perpendicular to the acceleration. These behaviors are qualitatively different from those of dust 'passively' driven by external hydrodynamic turbulence, with no back-reaction force from dust onto gas. The virulent nature of these instabilities has interesting implications for dust-driven winds in a variety of astrophysical systems, including around cool-stars, in dusty torii around active-galactic-nuclei, and in and around giant molecular clouds.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/1810.08214arXivDiscussion Paper
ORCID:
AuthorORCID
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:We would like to thank Stefania Moroianu for a number of helpful discussions. Support for PFH, JS, & ERM 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. Numerical calculations were run on the Caltech compute cluster “Wheeler,” allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
NSFAST-1715847
NSFAST-1455342
NASANNX15AT06G
JPL1589742
JPL17-ATP17-0214
NSFTG-AST130039
NSFOAC-1713353
NASASMD-16-7592
Subject Keywords:instabilities — turbulence — ISM: kinematics and dynamics — star formation: general— galaxies: formation— planets and satellites: formation
Record Number:CaltechAUTHORS:20190206-105610955
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190206-105610955
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92722
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:08 Feb 2019 15:23
Last Modified:08 Feb 2019 15:23

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