Peña-Monferrer C, Antao S, Manson-Sawko R
IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom.
Phys Fluids (1994). 2021 Dec;33(12):123314. doi: 10.1063/5.0070625. Epub 2021 Dec 21.
Asymptomatic virus transmission in public transportation is a complex process that is difficult to analyze computationally and experimentally. We present a high-resolution computational study for investigating droplet dynamics under a speech-like exhalation mode. A large eddy simulation coupled with Lagrangian tracking of drops was used to model a rectangular space with sitting thermal bodies and cross-ventilated with a multislot diffuser. Release of drops from different seat positions was evaluated to analyze the decontamination performance of the ventilation system. The results showed an overall good performance, with an average of 24.1% of droplets removed through the exhaust in the first 40 s. The droplets' distribution revealed that higher concentrations were less prevalent along the center of the domain where the passengers sit. Longitudinal contamination between rows was noted, which is a negative aspect for containing the risk of infection in a given row but has the benefit of diluting the concentration of infectious droplets. Droplets from the window seat raised more vertically and invaded the space of other passengers to a lesser extent. In contrast, droplets released from the middle seat contaminated more the aisle passenger's space, indicating that downward flow from personal ventilation could move down droplets to its breathing region. Droplets released from the aisle were dragged down by the ventilation system immediately. The distance of drops to the mouth of the passengers showed that the majority passed at a relatively safe distance. However, a few of them passed at a close distance of the order of magnitude of 1 cm.
公共交通中无症状病毒传播是一个复杂的过程，难以通过计算和实验进行分析。我们开展了一项高分辨率计算研究，以调查类似说话呼气模式下的液滴动力学。采用大涡模拟结合液滴的拉格朗日追踪，对有坐着的热人体且通过多缝式扩散器进行横向通风的矩形空间进行建模。评估了不同座位位置的液滴释放情况，以分析通风系统的净化性能。结果显示整体性能良好，在前40秒内平均有24.1%的液滴通过排气口排出。液滴分布表明，在乘客就座区域的中心沿线，较高浓度的情况不太普遍。注意到排与排之间存在纵向污染，这对于控制给定排内的感染风险而言是不利方面，但有利于稀释传染性液滴的浓度。靠窗座位的液滴上升得更高，对其他乘客空间的侵入程度较小。相比之下，中间座位释放的液滴对过道乘客空间的污染更大，这表明个人通风产生的向下气流会将液滴向下移动到其呼吸区域。从过道释放的液滴会立即被通风系统拖下。液滴到乘客嘴部的距离表明，大多数液滴是在相对安全的距离通过的。然而，其中有少数液滴是在约1厘米的近距离通过的。
