Colliding respiratory jets as a mechanism of air exchange and pathogen transport during conversations
Colliding respiratory jets as a mechanism of air exchange and pathogen transport during conversations
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DOI：
10.1017/jfm.2021.915
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发表时间：
2021-11-16
影响因子：
3.7
通讯作者：
Stone, Howard A.
中科院分区：
文献类型：
--
作者：
Giri, Arghyanir;Biswas, Neelakash;Stone, Howard A.
在新冠肺炎大流行中，人与人之间的空气交流已成为传播SARS-CoV-2病毒的重要媒介。我们研究了两个未戴面具的人之间的气流和交换，近距离面对面交谈，这可能会传播高剂量的病原体，因为与远程空气传播相比，稀释较小。我们进行了流动可视化实验和直接的呼吸射流碰撞的数值模拟，模拟了对话的初始阶段。喷流的演化和动力学受到扬声器嘴之间垂直偏移的影响。在低偏移量时，喷嘴的迎头碰撞会产生“阻塞效应”，暂时使易受影响的扬声器免受携带病原体的喷嘴的影响，尽管喷嘴的横向扩散增强了。足够大的偏移量会阻止喷嘴之间的相互作用。在中等偏移量(8-10厘米，间隔1米)，喷流卷吸和吸入有助于将携带病原体的唾液滴输送到易感说话者的嘴巴。尽管两个扬声器的呼吸喷流相互作用会产生阻塞效应，但预计会进行空气交换。
Air exchange between people has emerged in the COVID-19 pandemic as the important vector for transmission of the SARS-CoV-2 virus. We study the airflow and exchange between two unmasked individuals conversing face-to-face at short range, which can potentially transfer a high dose of a pathogen, because the dilution is small when compared to long-range airborne transmission. We conduct flow visualization experiments and direct numerical simulations of colliding respiratory jets mimicking the initial phase of a conversation. The evolution and dynamics of the jets are affected by the vertical offset between the mouths of the speakers. At low offsets the head-on collision of jets results in a `blocking effect', temporarily shielding the susceptible speaker from the pathogen carrying jet, although, the lateral spread of the jets is enhanced. Sufficiently large offsets prevent the interaction of the jets. At intermediate offsets (8-10 cm for 1 m separation), jet entrainment and the inhaled breath assist the transport of the pathogen-loaded saliva droplets towards the susceptible speaker's mouth. Air exchange is expected, in spite of the blocking effect arising from the interaction of the respiratory jets from the two speakers.