Direct numerical simulation of the turbulent flow generated during a violent expiratory event.
Direct numerical simulation of the turbulent flow generated during a violent expiratory event.
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DOI：
10.1063/5.0042086
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发表时间：
2021-03-01
期刊：
影响因子：
--
通讯作者：
Pallarès J
中科院分区：
文献类型：
--
作者：
Fabregat A;Gisbert F;Vernet A;Dutta S;Mittal K;Pallarès J
SARS-CoV-2（严重急性呼吸道综合征冠状病毒）传播的主要途径包括人说话、咳嗽或打喷嚏时产生的空气飞沫和气溶胶。这些携带病毒的气溶胶的停留时间和空间范围主要由它们的大小和背景流分散它们的能力控制。因此，更好地理解由呼吸事件驱动的流动所发挥的作用是估计载有病原体的颗粒传播感染的能力的关键。在这里，我们数值研究的流体动力学产生的暴力呼气事件类似于轻微的咳嗽。咳嗽可分为初始喷射阶段和耗散阶段，在初始喷射阶段期间，空气通过嘴排出，在耗散阶段期间，随着抽吸穿透环境，湍流强度衰减。由于咳嗽和环境空气之间的温度差而引起的随时间变化的呼出速度和浮力影响整体流动动力学。一个理想化的孤立咳嗽的直接数值模拟（DNS）是用来表征射流/喷烟动力学使用的领先湍流涡环的轨迹，并提取其拓扑结构通过拟合椭圆体的呼出流体轮廓。模拟咳嗽的三维结构表明，假设一个球状的喷烟前未能捕捉到观察到的椭圆形。数值结果表明，虽然分析模型提供了合理的估计的距离由喷烟，轨迹预测表现出较大的偏差从DNS。这里提出的完全解析的流体动力学可以用于通知新的分析模型，从而改善咳嗽引起的病原体负载气溶胶分散的预测。
A main route for SARS-CoV-2 (severe acute respiratory syndrome coronavirus) transmission involves airborne droplets and aerosols generated when a person talks, coughs, or sneezes. The residence time and spatial extent of these virus-laden aerosols are mainly controlled by their size and the ability of the background flow to disperse them. Therefore, a better understanding of the role played by the flow driven by respiratory events is key in estimating the ability of pathogen-laden particles to spread the infection. Here, we numerically investigate the hydrodynamics produced by a violent expiratory event resembling a mild cough. Coughs can be split into an initial jet stage during which air is expelled through mouth and a dissipative phase over which turbulence intensity decays as the puff penetrates the environment. Time-varying exhaled velocity and buoyancy due to temperature differences between the cough and the ambient air affect the overall flow dynamics. The direct numerical simulation (DNS) of an idealized isolated cough is used to characterize the jet/puff dynamics using the trajectory of the leading turbulent vortex ring and extract its topology by fitting an ellipsoid to the exhaled fluid contour. The three-dimensional structure of the simulated cough shows that the assumption of a spheroidal puff front fails to capture the observed ellipsoidal shape. Numerical results suggest that, although analytical models provide reasonable estimates of the distance traveled by the puff, trajectory predictions exhibit larger deviations from the DNS. The fully resolved hydrodynamics presented here can be used to inform new analytical models, leading to improved prediction of cough-induced pathogen-laden aerosol dispersion.
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影响因子：
4.6
作者：
Boersma, BJ;Brethouwer, G;Nieuwstadt, FTM
通讯作者：
Nieuwstadt, FTM
DOI：
10.1063/5.0034032
发表时间：
2020-12-01
期刊：
Physics of fluids (Woodbury, N.Y. : 1994)
影响因子：
--
作者：
Chaudhuri S;Basu S;Saha A
通讯作者：
Saha A
影响因子：
3.7
作者：
Bourouiba, Lydia;Dehandschoewercker, Eline;Bush, John W. M.
通讯作者：
Bush, John W. M.
影响因子：
4.6
作者：
Abani, Neerav;Reitz, Rolf D.
通讯作者：
Reitz, Rolf D.
影响因子：
3.7
作者：
GLEZER, A;COLES, D
通讯作者：
COLES, D