Comprehensive Computational Study on the Influences of Particle Size and Relative Humidity on Aerosol/Droplet Transmission in a Ventilated Room Under Stationary and Dynamic Conditions

Abstract

Given the concerns surrounding the possibility of crosscontamination caused by the airborne transmission of respiratory aerosols (> 5 μm in diameter) and droplets (> 5 μm in diameter) containing infectious viruses, there is a great need for simulations that reliably characterize the behaviour of these particles in real-world scenarios. This study performs a comprehensive transient CFD analysis to investigate the transmission of virus-carrying aerosols and droplets released through coughing by a mobile patient within a typical room equipped with a ventilation system. This computational study elaborately examines how particle size and relative humidity impact the dispersion of aerosols and droplets carrying virus in both mobile and stationary conditions of patients. To enhance the accuracy of this study, effective factors such as evaporation of liquid content within aerosols and droplets and random distribution of the particles, along with considerations for buoyancy, drag, lift, Brownian motion, and gravitational forces, are taken into account. To investigate the influence of aerosol and droplet size, this study considers uniform size distributions of 1, 10, and 100 μm in diameter, comprising 98.2% liquid water and 1.8% solid content. Additionally, different relative humidity levels, 0%, 50%, and 90%, are incorporated to indicate their impact on the dispersion pattern and residence time of the particles in both stationary and dynamic scenarios. According to the results, high levels of relative humidity and individuals’ movement significantly affect the turbulence intensity, airflow pattern, travelling distance, residence time and trajectory of particles, air pressure, and density distributions in such environments.