Dispersion behaviors of exhaled droplets under a displacement ventilated room: Lagrangian simulations

This paper adopts an Eulerian-Lagrangian approach to investigate the dispersion behaviors of human exhaled droplets under the displacement ventilation in a typical office room. A particle source in-cell (PSI-C) scheme is used to correlate the concentration with the Lagrangian particle trajectories in computational cells. Droplets with size from 0.1-20μm are released from a numerical thermal manikin’s (NTM) nose or mouth with different initial momentums and directions. The possible cross-infection risk caused by the exhaled infectious droplets is investigated. It is found that droplets exhaled from the NTM’s nose could be caught by its thermal plume whereas droplets exhaled from the NTM’s mouth could penetrate the thermal plume. Droplet sizes affect their dispersion behaviors. The cross-infection risk is small and doesn’t depend a lot on the ventilation conditions in this study.