Modelling of coughed droplets in a hospital ward

Coughing and its importance for spreading respiratory infectious diseases has been confirmed in many previous studies. The dispersion process of respiratory droplets released by the coughing of a patient in a hospital ward was studied using computational fluid dynamics simulation. Two relatively realistic three-dimensional thermal mannequins with a parallel bed arrangement simulated the patients. The maximum dispersion distances in time under ward ventilation conditions were studied. A velocity profile simulated a time-dependent cough with total duration of 0.4 s. The results indicated that the transport characteristic of droplets due to coughing is highly influenced by their size. Although the effects of gravity or inertia on small droplets (< 40 μm) are negligible and the indoor airflow mostly influences their transport, droplets of > 40 μm are significantly affected by gravity and soon fall as the strong coughing airflow field becomes weaker and the droplets separate from the general flow.