Influence of Airflow on Dispersion of COVID-19 Droplets in Classrooms Using Computational Fluid Dynamics

COVID-19, caused by the 2019-nCoV coronavirus, is a global pandemic that spreads through respiratory droplets that are transmitted by inhalation or contact with droplet nuclei produced during sneezing, coughing, and speaking by infected people. COVID-19 can also be spread by air in the infected person’s close-by surroundings. In this study, computational fluid dynamics (CFD) was employed to analyze the airborne transport of virus-laden droplets generated by a coughing event in a typical classroom environment. Simulations were conducted for three ventilation airflow velocities—3, 5, and 7 m/s—under both side and top wall configurations. The results showed that higher airflow velocities significantly reduced the residence time of airborne particles, with the 7 m/s case clearing over 90% of droplets within 60 seconds. Top wall ventilation led to early dispersion near the front rows, while side wall ventilation carried droplets to the rear seats over time. In addition, smaller aerosols (< 1 µm) remained suspended for a significantly longer duration than larger droplets (> 100 µm), indicating higher long-range transmission risk. These findings underscore the importance of optimizing airflow velocity and vent placement to reduce airborne exposure and support safer classroom ventilation design.