Violent expiratory events: on coughing and sneezing
Violent expiratory events: on coughing and sneezing
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DOI：
10.1017/jfm.2014.88
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发表时间：
2014-04-01
影响因子：
3.7
通讯作者：
Bush, John W. M.
中科院分区：
文献类型：
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作者：
Bourouiba, Lydia;Dehandschoewercker, Eline;Bush, John W. M.
咳嗽和喷嚏等剧烈呼吸事件在传染性疾病和易感人群之间的传播中起着关键作用。我们展示了对此类剧烈呼气事件的流体动力学进行实验和理论综合研究的结果。对打喷嚏和咳嗽事件的直接观察表明，此类气流是多相湍流浮力云，其中有各种大小的悬浮液滴。我们的观察结果指导我们建立了一个含病原体液滴与湍流浮力动量团相互作用的理论模型。为了预测病原体的范围，我们依次建立了离散和连续的液滴从云中降落的模型。根据离散沉降模型，液滴会一直悬浮在云中，直到其沉降速度与减速云的沉降速度相匹配。通过调整湍流流体的沉降模型，我们建立了一个连续沉降模型。理论模型的预测结果通过一系列模拟实验中收集的数据进行了测试，在这些模拟实验中，充满颗粒的云被喷射到相对稠密的环境中。我们的研究强调了呼吸道云的多相性质的重要性，特别是云内循环对最小微滴的悬浮作用，从而扩大了呼吸道病原体的传播范围。
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.