The dispersion of viral droplets plays a key role in the transmission of COVID-19. In this work, we analyze the dispersion of cough-generated droplets in the wake of a walking person for different space sizes. The air flow is simulated by solving the Reynolds-averaged Navier–Stokes equations, and the droplets are modeled as passive Lagrangian particles. Simulation results show that the cloud of droplets locates around and below the waist height of the manikin after 2 s from coughing, which indicates that kids walking behind an infectious patient are exposed to higher transmission risk than adults. More importantly, two distinct droplet dispersion modes occupying significantly different contamination regions are discovered. A slight change of space size is found being able to trigger the transition of dispersion modes even though the flow patterns are still similar. This shows the importance of accurately simulating the air flow in predicting the dispersion of viral droplets and implies the necessity to set different safe-distancing guidelines for different environments.

中文翻译：

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空间大小对步行者咳嗽产生的飞沫扩散的影响

病毒飞沫的扩散在 COVID-19 的传播中起着关键作用。在这项工作中，我们分析了在不同空间大小下行走的人后咳嗽产生的飞沫的分散情况。通过求解雷诺平均 Navier-Stokes 方程来模拟气流，并将液滴建模为被动拉格朗日粒子。模拟结果表明，在咳嗽 2 秒后，飞沫云位于人体模型腰部高度的周围和下方，这表明走在感染患者身后的孩子比成年人面临更高的传播风险。更重要的是，发现了两种不同的液滴分散模式，它们占据了显着不同的污染区域。发现空间大小的轻微变化能够触发分散模式的转变，即使流动模式仍然相似。这表明准确模拟空气流动在预测病毒飞沫扩散方面的重要性，并暗示有必要为不同环境设置不同的安全距离准则。