Modeling Evaporation of Water Droplets as Applied to Survival of Airborne Viruses
Modeling Evaporation of Water Droplets as Applied to Survival of Airborne Viruses
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DOI：
10.3390/atmos11090965
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发表时间：
2020-09-01
期刊：
影响因子：
2.9
通讯作者：
Nosonovsky, Michael
中科院分区：
文献类型：
--
作者：
Dombrovsky, Leonid A.;Fedorets, Alexander A.;Nosonovsky, Michael
许多病毒，如冠状病毒，往往会在空气中通过微滴传播。微滴的蒸发可能会降低它们的传染性。然而，小液滴的蒸发是一个涉及传质、传热、扩散、对流和太阳辐射吸收的复杂过程。病毒学研究表明，空气传播的病毒存活对空气湿度和温度非常敏感。我们采用了一个考虑了努森层的液滴蒸发模型。该模型表明，蒸发对环境空气的温度和相对湿度(RH)都很敏感。我们还讨论了各种机制，如太阳辐射的影响，环境空气中运动液滴的动态松弛，以及液滴的重力沉积。对晴空下光谱辐射通量的最大估计值表明，辐射对单个水滴蒸发的贡献不大。我们的结论是，在小相对湿度甚至中等高相对湿度下，微滴在几十秒内蒸发，空气中的对流热流在每种情况下都是主要机制。文中得到的数值结果与已发表的实验室实验和许多病毒感染的季节性都很好地定性一致。可能需要复杂的实验技术来原位观察病毒与有机颗粒和微滴中的活细胞的相互作用。新的受控液滴团簇技术被认为是这种实验方法学的一种有前途的候选技术。
Many viruses, such as coronaviruses, tend to spread airborne inside water microdroplets. Evaporation of the microdroplets may result in a reduction of their contagiousness. However, the evaporation of small droplets is a complex process involving mass and heat transfer, diffusion, convection and solar radiation absorption. Virological studies indicate that airborne virus survival is very sensitive to air humidity and temperature. We employ a model of droplet evaporation with the account for the Knudsen layer. This model suggests that evaporation is sensitive to both temperature and the relative humidity (RH) of the ambient air. We also discuss various mechanisms such as the effect of solar irradiation, the dynamic relaxation of moving droplets in ambient air and the gravitational sedimentation of the droplets. The maximum estimate for the spectral radiative flux in the case of cloudless sky showed that the radiation contribution to evaporation of single water droplets is insignificant. We conclude that at small and even at moderately high levels of RH, microdroplets evaporate within dozens of seconds with the convective heat flux from the air being the dominant mechanism in every case. The numerical results obtained in the paper are in good qualitative agreement with both the published laboratory experiments and seasonal nature of many viral infections. Sophisticated experimental techniques may be needed for in situ observation of interaction of viruses with organic particles and living cells within microdroplets. The novel controlled droplet cluster technology is suggested as a promising candidate for such experimental methodology.