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Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event

Airborne particles are a major route for transmission of COVID-19 and many other infectious diseases. When a person talks, sings, coughs, or sneezes, nasal and throat secretions are spewed into the air. After a short initial fragmentation stage, the expelled material is mostly composed of spherical...

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Autores principales: Fabregat, Alexandre, Gisbert, Ferran, Vernet, Anton, Ferré, Josep Anton, Mittal, Ketan, Dutta, Som, Pallarès, Jordi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: AIP Publishing LLC 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060975/
https://www.ncbi.nlm.nih.gov/pubmed/33897242
http://dx.doi.org/10.1063/5.0045416
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author Fabregat, Alexandre
Gisbert, Ferran
Vernet, Anton
Ferré, Josep Anton
Mittal, Ketan
Dutta, Som
Pallarès, Jordi
author_facet Fabregat, Alexandre
Gisbert, Ferran
Vernet, Anton
Ferré, Josep Anton
Mittal, Ketan
Dutta, Som
Pallarès, Jordi
author_sort Fabregat, Alexandre
collection PubMed
description Airborne particles are a major route for transmission of COVID-19 and many other infectious diseases. When a person talks, sings, coughs, or sneezes, nasal and throat secretions are spewed into the air. After a short initial fragmentation stage, the expelled material is mostly composed of spherical particles of different sizes. While the dynamics of the largest droplets are dominated by gravitational effects, the smaller aerosol particles, mostly transported by means of hydrodynamic drag, form clouds that can remain afloat for long times. In subsaturated air environments, the dependence of pathogen-laden particle dispersion on their size is complicated due to evaporation of the aqueous fraction. Particle dynamics can significantly change when ambient conditions favor rapid evaporation rates that result in a transition from buoyancy-to-drag dominated dispersion regimes. To investigate the effect of particle size and evaporation on pathogen-laden cloud evolution, a direct numerical simulation of a mild cough was coupled with an evaporative Lagrangian particle advection model. The results suggest that while the dispersion of cough particles in the tails of the size distribution are unlikely to be disrupted by evaporative effects, preferential aerosol diameters (30–40 μm) may exhibit significant increases in the residence time and horizontal range under typical ambient conditions. Using estimations of the viral concentration in the spewed fluid and the number of ejected particles in a typical respiratory event, we obtained a map of viral load per volume of air at the end of the cough and the number of virus copies per inhalation in the emitter vicinity.
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spelling pubmed-80609752021-04-22 Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event Fabregat, Alexandre Gisbert, Ferran Vernet, Anton Ferré, Josep Anton Mittal, Ketan Dutta, Som Pallarès, Jordi Phys Fluids (1994) ARTICLES Airborne particles are a major route for transmission of COVID-19 and many other infectious diseases. When a person talks, sings, coughs, or sneezes, nasal and throat secretions are spewed into the air. After a short initial fragmentation stage, the expelled material is mostly composed of spherical particles of different sizes. While the dynamics of the largest droplets are dominated by gravitational effects, the smaller aerosol particles, mostly transported by means of hydrodynamic drag, form clouds that can remain afloat for long times. In subsaturated air environments, the dependence of pathogen-laden particle dispersion on their size is complicated due to evaporation of the aqueous fraction. Particle dynamics can significantly change when ambient conditions favor rapid evaporation rates that result in a transition from buoyancy-to-drag dominated dispersion regimes. To investigate the effect of particle size and evaporation on pathogen-laden cloud evolution, a direct numerical simulation of a mild cough was coupled with an evaporative Lagrangian particle advection model. The results suggest that while the dispersion of cough particles in the tails of the size distribution are unlikely to be disrupted by evaporative effects, preferential aerosol diameters (30–40 μm) may exhibit significant increases in the residence time and horizontal range under typical ambient conditions. Using estimations of the viral concentration in the spewed fluid and the number of ejected particles in a typical respiratory event, we obtained a map of viral load per volume of air at the end of the cough and the number of virus copies per inhalation in the emitter vicinity. AIP Publishing LLC 2021-03 2021-03-31 /pmc/articles/PMC8060975/ /pubmed/33897242 http://dx.doi.org/10.1063/5.0045416 Text en © 2021 Author(s) Published under license by AIP Publishing. 1070-6631/2021/33(3)/033329/13/$30.00 https://creativecommons.org/licenses/by/4.0/All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ).
spellingShingle ARTICLES
Fabregat, Alexandre
Gisbert, Ferran
Vernet, Anton
Ferré, Josep Anton
Mittal, Ketan
Dutta, Som
Pallarès, Jordi
Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title_full Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title_fullStr Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title_full_unstemmed Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title_short Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
title_sort direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event
topic ARTICLES
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060975/
https://www.ncbi.nlm.nih.gov/pubmed/33897242
http://dx.doi.org/10.1063/5.0045416
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