CFD Simulation of Human Coughs and Sneezes: A Study in Droplet Dispersion, Heat, and Mass Transfer

A Computational Fluid Dynamics simulation of near-field cough and sneeze droplet dispersion and heat and mass transfer is developed. In this study various sources of variability in cough and sneeze processes are considered. These are variations in injection volume (0.5l, 2.5l, and 5.0l) and ambient relative humidity (20%, 40% and 60%). There are a total of 9 simulations for coughs and sneezes in a quiescent background. A large ensemble (5000) of droplets are tracked with diameters in the range 1–500micron. Evaporation and dispersion are predicted as a function of droplet size. Generally, fine droplets evaporate faster than large droplets. Higher relative humidities slow the evaporation process. Larger droplets have greater axial penetration. They also exhibit greater vertical drop due to the effect of gravity. Sideway penetration is increased by higher injection volumes. The buoyancy effect due to thermal energy of the injection is very weak, at least for the 10-second computation duration.