Spatiotemporal evolution of aerosols from cough airflow within the partitioned desk area in quiescent air

Abstract

To mitigate potential infection risks, desks with partitions are widely adopted in public spaces. However, aerosol transmission within such areas remains underexplored. In this study, a series of experiments were conducted using Particle Image Velocimetry and an Aerodynamic Particle Sizer to investigate the mechanisms and dynamics of cough airflow, as well as the spatiotemporal evolution of aerosols generated by the airflow. The results reveal that cough airflow behaviour can be categorized into two distinct regimes. Regime I is characterized by a high-velocity jet phase followed by a puffing phase, during which the airflow exhibits well-defined structures and strong dynamics. In Regime II, after the airflow impacts the wall, intrusion flows form and spread along the wall, extending into the surrounding space. Further analysis integrating flow field dynamics with the spatiotemporal evolution of size-resolved aerosol concentrations highlights the critical role of the puff cloud in mixing aerosols with the surrounding air and increasing aerosol concentrations within the affected area. The findings also indicate that intrusion flows are particularly effective at transporting aerosol particles smaller than 7 μm over longer distances. The efficiency of aerosol transport depends on both the number of intrusion flows generated and their initial momentum. Within partitioned areas, these fine aerosols tend to remain suspended for extended periods. By combining insights from fluid dynamics and aerosol behavior, this study elucidates the distinct contributions of both the puff cloud and intrusion flows to aerosol transport, underscoring the potential risks of aerosol transmission within partitioned spaces.