The University of Southampton
University of Southampton Institutional Repository

Observation of aerodynamic instability in the flow of a particle stream in a dilute gas

Observation of aerodynamic instability in the flow of a particle stream in a dilute gas
Observation of aerodynamic instability in the flow of a particle stream in a dilute gas

Forming macroscopic solid bodies in circumstellar discs requires local dust concentration levels significantly higher than the mean. Interactions of the dust particles with the gas must serve to augment local particle densities, and facilitate growth past barriers in the metre size range. Amongst a number of mechanisms that can amplify the local density of solids, aerodynamic streaming instability (SI) is one of the most promising. This work tests the physical assumptions of models that lead to SI in protoplanetary discs (PPDs). We conduct laboratory experiments in which we track the three-dimensional motion of spherical solid particles fluidised in a low-pressure, laminar, incompressible, gas stream. The particle sizes span the Stokes-Epstein drag regime transition and the overall dust-to-gas mass density ratio, is close to unity. A recently published study establishes the similarity of the laboratory flow to a simplified PPD model flow. We study velocity statistics and perform time-series analysis of the advected flow to obtain experimental results suggesting an instability due to particle-gas interaction: (i) there exist variations in particle concentration in the direction of the mean relative motion between the gas and the particles, that is the direction of the mean drag forces; (ii) the particles have a tendency to catch up to one another when they are in proximity; (iii) particle clumping occurs on very small scales, which implies local enhancements above the background by factors of several tens; (iv) the presence of these density enhancements occurs for a mean approaching or greater than 1; (v) we find evidence for collective particle drag reduction when the local particle number density becomes high and when the background gas pressure is high so that the drag is in the continuum regime. The experiments presented here are precedent-setting for observing SI under controlled conditions and may lead to a deeper understanding of how it operates in nature.

Hydrodynamics, Instabilities, Planets and satellites: formation, Protoplanetary disks, Turbulence
0004-6361
Capelo, Holly L.
18bc345d-887f-40b7-8eb8-0bbb1b8e24ab
Molaček, Jan
ef9ece8f-7864-4805-9743-e7dac738dbff
Lambrechts, Michiel
844c0ede-c0f2-4007-a68b-897f735fc3a0
Lawson, John
4e0b1895-51c5-41e6-9322-7f79e76e0e4c
Johansen, Anders
32aa4f39-923c-49da-815f-7c6050ed9d2d
Blum, Jürgen
747e8127-435a-4cbc-8125-aa69612f2c8a
Bodenschatz, Eberhard
e8658e96-6c7b-4385-94fa-a23fb68edeb5
Xu, Haitao
2108313f-1485-42f6-afb0-58d4c93ec35b
Capelo, Holly L.
18bc345d-887f-40b7-8eb8-0bbb1b8e24ab
Molaček, Jan
ef9ece8f-7864-4805-9743-e7dac738dbff
Lambrechts, Michiel
844c0ede-c0f2-4007-a68b-897f735fc3a0
Lawson, John
4e0b1895-51c5-41e6-9322-7f79e76e0e4c
Johansen, Anders
32aa4f39-923c-49da-815f-7c6050ed9d2d
Blum, Jürgen
747e8127-435a-4cbc-8125-aa69612f2c8a
Bodenschatz, Eberhard
e8658e96-6c7b-4385-94fa-a23fb68edeb5
Xu, Haitao
2108313f-1485-42f6-afb0-58d4c93ec35b

Capelo, Holly L., Molaček, Jan, Lambrechts, Michiel, Lawson, John, Johansen, Anders, Blum, Jürgen, Bodenschatz, Eberhard and Xu, Haitao (2019) Observation of aerodynamic instability in the flow of a particle stream in a dilute gas. Astronomy and Astrophysics, 622, [A151]. (doi:10.1051/0004-6361/201833702).

Record type: Article

Abstract

Forming macroscopic solid bodies in circumstellar discs requires local dust concentration levels significantly higher than the mean. Interactions of the dust particles with the gas must serve to augment local particle densities, and facilitate growth past barriers in the metre size range. Amongst a number of mechanisms that can amplify the local density of solids, aerodynamic streaming instability (SI) is one of the most promising. This work tests the physical assumptions of models that lead to SI in protoplanetary discs (PPDs). We conduct laboratory experiments in which we track the three-dimensional motion of spherical solid particles fluidised in a low-pressure, laminar, incompressible, gas stream. The particle sizes span the Stokes-Epstein drag regime transition and the overall dust-to-gas mass density ratio, is close to unity. A recently published study establishes the similarity of the laboratory flow to a simplified PPD model flow. We study velocity statistics and perform time-series analysis of the advected flow to obtain experimental results suggesting an instability due to particle-gas interaction: (i) there exist variations in particle concentration in the direction of the mean relative motion between the gas and the particles, that is the direction of the mean drag forces; (ii) the particles have a tendency to catch up to one another when they are in proximity; (iii) particle clumping occurs on very small scales, which implies local enhancements above the background by factors of several tens; (iv) the presence of these density enhancements occurs for a mean approaching or greater than 1; (v) we find evidence for collective particle drag reduction when the local particle number density becomes high and when the background gas pressure is high so that the drag is in the continuum regime. The experiments presented here are precedent-setting for observing SI under controlled conditions and may lead to a deeper understanding of how it operates in nature.

This record has no associated files available for download.

More information

Published date: 1 February 2019
Keywords: Hydrodynamics, Instabilities, Planets and satellites: formation, Protoplanetary disks, Turbulence

Identifiers

Local EPrints ID: 455463
URI: http://eprints.soton.ac.uk/id/eprint/455463
ISSN: 0004-6361
PURE UUID: b81f061e-dee7-41b3-bb93-7189380e04d6
ORCID for John Lawson: ORCID iD orcid.org/0000-0003-3260-3538

Catalogue record

Date deposited: 22 Mar 2022 17:39
Last modified: 11 Jul 2024 02:03

Export record

Altmetrics

Contributors

Author: Holly L. Capelo
Author: Jan Molaček
Author: Michiel Lambrechts
Author: John Lawson ORCID iD
Author: Anders Johansen
Author: Jürgen Blum
Author: Eberhard Bodenschatz
Author: Haitao Xu

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×