Discrete Phase Modelling Simulation Study of Airborne Droplet Nuclei in a Classroom

Droplet nuclei are known to be the vehicle of airborne respiratory illness. Water droplets produced when humans breathe, sneeze, cough, and even sweat naturally contain cells, electrolytes, and sometimes infectious bacteria and viruses. Droplets larger than 5 μm in diameter tend to fall to the ground by gravity, while the core of smaller diameter droplets remains suspended in the air and moves with the air current. Computational fluid dynamics software using the discrete phase modelling technique examines the transmission distance of droplet nuclei with a diameter of 5–6 μm. The place of investigation is a classroom of 9 m (L) × 3.5 m (H). It is found that with the lower airflow of 1 m/s, and at a distance of 2 m, the concentration of 2.181 kg/m3 is recorded from the source to the student while at 2 m/s, the droplet nuclei concentrations are 1.77 kg/m3 and scattered to the end of the classroom. The method of evacuating the air from within was simulated and found to be the preferable method for directing the air out, with concentrations of 0.029 kg/m3 at a distance of 4 m.