A CFD Approach for Risk Assessment Based on Airborne Pathogen Transmission

Abstract

The outbreak of COVID-19 necessitates developing reliable tools to derive safety measures, including safe social distance and minimum exposure time under different circumstances. Transient Eulerian–Lagrangian computational fluid dynamics (CFD) models have emerged as a viably fast and economical option. Nonetheless, these CFD models resolve the instantaneous distribution of droplets inside a computational domain, making them incapable of directly being used to assess the risk of infection as it depends on the total accumulated dosage of infecting viruses received by a new host within an exposure time. This study proposes a novel risk assessment model (RAM) to predict the temporal and spatial accumulative concentration of infectious exhaled droplets based on the bio-source’s exhalation profile and droplet distribution using the CFD results of respiratory events in various environmental conditions. Unlike the traditional approach in the bulk movement assessment of droplets’ outreach in a domain, every single droplet is traced inside the domain at each time step, and the total number of droplets passing through any arbitrary position of the domain is determined using a computational code. The performance of RAM is investigated for a series of case studies against various respiratory events where the horizontal and the lateral spread of risky zones are shown to temporarily vary rather than being fixed in space. The sensitivity of risky zones to ambient temperature and relative humidity was also addressed for sample cough and sneeze cases. This implies that the RAM provides crucial information required for defining safety measures such as safety distances or minimum exposure times in different environments.

Practical Mitigation Strategies for Countering the Spread of Aerosolized COVID-19 Virus (SARS-CoV-2) Using Ventilation and HEPA Air Purifiers: A Literature Review

“…The researchers found this intervention to be "somewhat effective." D' Alessandro et al (2021) andMotamedi Zoka et al (2021) used the Eulerian-Lagrangian CFD approach to simulate the distribution of infectious exhaled droplets in various environments.…”

Numerical modeling of a sneeze, a cough and a continuum speech inside a hospital lift

“…There exist many studies addressed to health related safe measures. Motamedi Zoka et al [ 16 ] presented a new risk assessment model based on horizontal spreading of droplets and found a low propagation hazard in coughs, but a high droplet spreading for sneezes. According to this study, a low RH achieves more droplets spread but in lower concentrations than a high RH, case where the volumetric concentration is higher but in zones near to the source.…”

Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom

“…CFD simulation of exhaled droplets, during transmission indoors, has been studied by several researchers [17,[26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Most of the studied cases describe the transfer of exhaled droplets from an infected person to others under different locations, conditions, and ventilation systems.…”