Violent expiratory events: on coughing and sneezing
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Bourouiba_Violent expiratory events 3-25-15.pdf
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Author(s)
Bourouiba, Lydia
Dehandschoewercker, Eline
Bush, John W. M.
Date Issued
March 2014
Journal
Journal of Fluid Mechanics
Publisher
Cambridge University Press
Citation
Bourouiba, Lydia, Eline Dehandschoewercker, and John W. M. Bush. “Violent Expiratory Events: On Coughing and Sneezing.” Journal of Fluid Mechanics 745 (March 24, 2014): 537–563. © 2014 Cambridge University Press
Version
Final published version
Abstract
Violent respiratory events such as coughs and sneezes play a key role in transferring respiratory diseases between infectious and susceptible individuals. We present the results of a combined experimental and theoretical investigation of the fluid dynamics of such violent expiratory events. Direct observation of sneezing and coughing events reveals that such flows are multiphase turbulent buoyant clouds with suspended droplets of various sizes. Our observations guide the development of an accompanying theoretical model of pathogen-bearing droplets interacting with a turbulent buoyant momentum puff. We develop in turn discrete and continuous models of droplet fallout from the cloud in order to predict the range of pathogens. According to the discrete fallout model droplets remain suspended in the cloud until their settling speed matches that of the decelerating cloud. A continuous fallout model is developed by adapting models of sedimentation from turbulent fluids. The predictions of our theoretical models are tested against data gathered from a series of analogue experiments in which a particle-laden cloud is ejected into a relatively dense ambient. Our study highlights the importance of the multiphase nature of respiratory clouds, specifically the suspension of the smallest drops by circulation within the cloud, in extending the range of respiratory pathogens.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Mathematics
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1017/jfm.2014.88
