Yao Feng, Liu Xiangdong
Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China.
Phys Fluids (1994). 2021 Dec;33(12):123301. doi: 10.1063/5.0073171. Epub 2021 Dec 1.
The potential risk of spreading a virus during bus transportation motivates us to understand the aerosol transmission of SARS-CoV-2 and seek effective ways to protect passengers in a bus. In this paper, a typical scenario in which the virus spreads in a bus under a windless environment is numerically studied for further understanding of the spreading characteristics of aerosol transmission in an enclosed space. The air flow in the bus and the spreading processes of droplets with different open windows configurations are obtained and analyzed. The variations of droplet concentration in the air with time are examined and analyzed. In addition, the transient droplet concentration deposited on the passengers is also counted to analyze the potential contact transmission. The results indicate that opening a window next to an infected person shows an unsatisfactory performance in limiting droplet spreading range and reducing droplet concentration, eventually leading to a high risk of infection by aerosol transmission following contact transmission. In addition, opening multiple windows also shows an unsatisfactory result for removing droplets in a bus since the turbulence flow accelerates the spreading speed and expands the spreading range. In contrast, the droplets are removed from the indoor space of the bus quickly if a window is opened in the row in front of the infected person, which is beneficial for reducing aerosol and contact transmission in the bus. Furthermore, it is strongly recommended to avoid sitting in the row in front of the infected person where the highest droplet concentration can be observed.
公交车运输过程中病毒传播的潜在风险促使我们去了解严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的气溶胶传播，并寻求保护公交车乘客的有效方法。本文对一种典型场景进行了数值研究，即病毒在无风环境下于公交车内传播，以进一步了解封闭空间内气溶胶传播的扩散特性。获得并分析了公交车内的气流以及不同开窗配置下液滴的扩散过程。研究并分析了空气中液滴浓度随时间的变化情况。此外，还统计了沉积在乘客身上的瞬态液滴浓度，以分析潜在的接触传播情况。结果表明，在感染者旁边开窗在限制液滴扩散范围和降低液滴浓度方面表现不佳，最终导致在接触传播后通过气溶胶传播感染的风险很高。此外，打开多个窗户在去除公交车内的液滴方面也效果不佳，因为紊流会加速传播速度并扩大传播范围。相比之下，如果在感染者前方一排开窗，公交车室内空间的液滴会迅速被去除，这有利于减少公交车内的气溶胶和接触传播。此外，强烈建议避免坐在感染者前方一排，因为在那里可观察到最高的液滴浓度。
