Experimental and Simulation Study of Spatial Distribution of Human Respiratory Droplets under Typical Indoor Air Distribution Patterns

Abstract

This project is aimed to investigate the impact of the three typical distribution methods, namely the well-mixing, stratified and personalized ventilation methods, on the airborne and droplets transmitted infections in enclosed environments. The special focus is on the aerodynamic dispersion and deposition of the respiratory droplet residuals (RDR), and the key question is whether the three typical air distribution methods can make significant differences in reducing the infection risks from person to person at typical design airflow rates in general open plan office, meeting room and classroom environments.

Based upon the investigator's expertise and the review of the progresses in turbulent airflow and aerosol movement modeling, we will use modeling methods to investigate the problems. Bearing in mind some of the empirical and approximation features of turbulence models and aerosol dispersion and deposition modeling, a cautious two-step approach is adopted by first comparing the modeling results with the experimental results obtained at close to the realistic air flow conditions and examining the impact of the key assumptions of the model parameters, and then applying the models to the three realistic air flow conditions.

People with respiratory infectious disease carry viruses or bacteria in their respiratory fluids including saliva, sputum, and respiratory mucus. These viruses can be dispersed into the external environment in the form of droplets when infected person is breathing, talking, coughing or sneezing. Hosts without immunity are susceptible ones and vulnerable to the viruses. Infection may happen once pathogenladen droplets are inhaled and deposit onto certain locations of respiratory system, or reach mucous membrane by contact. Researches show that ventilation system preserve strong influences on the distribution of respiratory droplets and the transmission of infectious disease. This project systematically investigated the dispersion of human respiratory droplets under three commonly employed ventilation systems, and evaluated the occupant’s exposure at different situations. The outcome of this research can provide some insights in the design of ventilation system, layout of commercial buildings for reducing person to person infections via airborne route.