Mathai Varghese, Das Asimanshu, Breuer Kenneth
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Center for Fluid Mechanics, Brown University, Providence, Rhode Island 02912, USA.
Phys Fluids (1994). 2022 Feb;34(2):021904. doi: 10.1063/5.0079555. Epub 2022 Feb 7.
Identifying the potential routes of airborne transmission during transportation is of critical importance to limit the spread of the SARS-CoV-2 virus. Here, we numerically solve the Reynolds-averaged Navier-Stokes equations along with the transport equation for a passive scalar in order to study aerosol transmission inside the passenger cabin of an automobile. Extending the previous work on this topic, we explore several driving scenarios including the effects of having the windows fully open, half-open, and one-quarter open, the effect of opening a moon roof, and the scaling of the aerosol transport as a function of vehicle speed. The flow in the passenger cabin is largely driven by the external surface pressure distribution on the vehicle, and the relative concentration of aerosols in the cabin scales inversely with vehicle speed. For the simplified geometry studied here, we find that the half-open windows configuration has almost the same ventilation effectively as the one with the windows fully open. The utility of the moonroof as an effective exit vent for removing the aerosols generated within the cabin space is discussed. Using our results, we propose a "speed-time" map, which gives guidance regarding the relative risk of transmission between and as a function of trip duration and vehicle speed. A few strategies for the removal of airborne contaminants during low-speed driving, or in a situation where the vehicle is stuck in traffic, are suggested.
识别运输过程中空气传播的潜在途径对于限制新冠病毒的传播至关重要。在此，我们通过数值求解雷诺平均纳维-斯托克斯方程以及被动标量的输运方程，来研究汽车乘客舱内的气溶胶传播。在之前关于该主题工作的基础上进行拓展，我们探索了几种驾驶场景，包括车窗全开、半开和四分之一开的影响，开启天窗的影响，以及气溶胶输运随车速的变化规律。乘客舱内的气流主要由车辆外表面压力分布驱动，舱内气溶胶的相对浓度与车速成反比。对于此处研究的简化几何形状，我们发现半开窗配置的通风效果几乎与车窗全开时相同。讨论了天窗作为去除舱内产生的气溶胶的有效出口通风口的效用。利用我们的结果，我们提出了一个“速度-时间”图，它给出了作为行程持续时间和车速函数的、在不同车速下传播相对风险的指导。还提出了一些在低速行驶或车辆堵车情况下去除空气传播污染物的策略。
