Numerical comparison of ventilation modes on the transmission of coughing droplets in a train compartment

Abstract

The ventilation system in the indoor environments plays a significant role in controlling the cross-infection of viruses and the risk of infection. This work investigated the effects of prevailing high-speed train ventilation modes on the spatial distribution features of droplets through computational fluid dynamics (CFD) simulation. The results revealed that under the current ventilation modes, the airflow barrier was formed in the middle of the aisle, and more than 77.36% of the released droplets were limited to accumulate in the releasing side. Moreover, we found that the strong recirculation flows appeared in the circumstance of top air supply mode suppressed the longitudinal transport of droplets. Also, compared to the standard ventilation case of mixed air supply mode, the suspending droplet fraction in the breathing zone decreased by 37.9% for 10 μm after 60 s under top air supply mode, while those decreased by 33.7% for 50 μm. Therefore, the potential infection risk in the high-speed train was less when the air-condition unit implemented top air supply mode. The research outcomes can be useful to optimize air-conditioning flow and reduce the contagion risk in high-speed trains and other public transport environments with similar air supply strategies.