The motion of respiratory droplets produced by coughing

Abstract

Coronavirus disease 2019 (COVID-19) has become a global pandemic infectious respiratory disease with high mortality and infectiousness. This paper investigates respiratory droplet transmission, which is critical to understanding, modeling and controlling epidemics. In the present work, we implemented flow visualization, particle image velocimetry (PIV) and particle shadow tracking velocimetry (PSTV) to measure the velocity of the airflow and droplets involved in coughing and then constructed a physical model considering the evaporation effect to predict the motion of droplets under different weather conditions. The experimental results indicate that the convection velocity of cough airflow presents the relationship $t^{-0.7}$ with time; hence, the distance from the cougher increases by $t^{0.3}$ in the range of our measurement domain. Substituting these experimental results into the physical model reveals that the small droplets (initial diameter $D\le$ 100 $\mu$m) evaporate to droplet nuclei and that the large droplets with $D\ge$ 500 $\mu$m and initial velocity $u_0\ge$ 5 m/s travel more than 2 m. Winter conditions of low temperature and high relative humidity can cause more droplets to settle to the ground, which may be a possible driver of a second pandemic wave in the autumn and winter seasons.

arXiv comment27 pages, 15 figures, COVID-19, article

References in corpus (5)

• The Flow Physics of COVID-19
• Modeling ambient temperature and relative humidity sensitivity of respiratory droplets and their role in Covid-19 outbreaks
• A Mathematical Framework for Estimating Risk of Airborne Transmission of COVID-19 with Application to Face Mask Use and Social Distancing
• Visualizing droplet dispersal for face shields and masks with exhalation valves
• Effects of space sizes on the dispersion of cough-generated droplets from a walking person

Cited by in corpus (6)

• Aerosol generation in public restrooms
• Effects of space sizes on the dispersion of cough-generated droplets from a walking person
• Risk Assessment of COVID Infection by Respiratory Droplets from Cough for Various Ventilation Scenarios Inside an Elevator An OpenFOAM based Computational Fluid Dynamic Analysis
• Eulerian-Lagrangian modelling of bio-aerosols irradiated by UV-C light in relation to SARS-CoV-2 transmission
• Airborne virus transmission under different weather conditions
• Airborne Virus Transmission: Increased Spreading Due to Formation of Hollow Particles