The transport and fate of human expiratory droplets play a key role in the transmission of respiratory infectious diseases. In this paper, we present a modeling approach to understand the fundamental dynamics of exhaled droplets in human respiratory activities. The model solves a series of governing equations of droplets and uses a continuous random walk model to simulate turbulent fluctuations in violent expiratory events. The validation of the model shows the improvement in the prediction of dispersion of median-sized droplets. We show that these droplets are sensitive to environmental conditions, including temperature, humidity, and ambient flows. Applying the model to a set of idealized conditions such as free-fall and continuous jets, we demonstrate significantly different impacts of environmental parameters on droplets with different sizes. Using a realistic droplet size distribution and cough duration, we quantify the transport and fate of droplets in the near field of source and the potential influences by ambient conditions. The model we developed from this study could be applied to study the mechanisms for airborne pathogens, e.g., influenza virus and new coronavirus.

中文翻译：

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人类呼出液滴的运输和归宿——一种建模方法

人类呼出飞沫的运输和归宿在呼吸道传染病的传播中起着关键作用。在本文中，我们提出了一种建模方法来了解人类呼吸活动中呼出液滴的基本动力学。该模型求解一系列液滴的控制方程，并使用连续随机游走模型来模拟剧烈呼气事件中的湍流波动。该模型的验证显示了对中等尺寸液滴的分散预测的改进。我们表明这些液滴对环境条件敏感，包括温度、湿度和环境流量。将该模型应用于一组理想化条件，例如自由落体和连续射流，我们证明了环境参数对不同尺寸液滴的显着不同影响。使用真实的液滴尺寸分布和咳嗽持续时间，我们量化了液滴在源近场中的运输和归宿以及环境条件的潜在影响。我们从这项研究中开发的模型可用于研究空气传播病原体的机制，例如流感病毒和新型冠状病毒。