Sneezing and asymptomatic virus transmission

Abstract

The novel coronavirus disease (COVID-19) spread pattern continues to show that geographical barriers alone cannot contain a virus. Asymptomatic carriers play a critical role in the nature of this virus quickly escalating into a global pandemic. Asymptomatic carriers may transmit the virus unintentionally through sporadic sneezing. A novel Computational Fluid Dynamics (CFD) approach has been proposed with a realistic modeling of a human sneeze achieved by the combination of state-of-the-art experimental and numerical methods. This modeling approach may be suitable for future engineering analyses aimed at reshaping public spaces and common areas, with the main objective to accurately predict the spread of aerosol and droplets that may contain pathogens. This study shows that the biomechanics of a human sneeze, including complex muscle contractions and relaxations, can be accurately modeled by the angular head motion and the dynamic pressure response during sneezing. These have been considered as the human factors and were implemented in the CFD simulation by imposing a momentum source term to the coupled Eulerian–Lagrangian momentum equations. The momentum source was modeled by the measured dynamic pressure response in conjunction with the angular head motion. This approach eliminated the need to create an ad hoc set of inlet boundary conditions. With this proposed technique, it is easier to add multiple fixed and/or moving sources of sneezes in complex computational domains. Additionally, extensive sensitivity analyses based on different environmental conditions were performed, and their impact was described in terms of potential virus spread.

Numerical investigation of aerosol transport in a classroom with relevance to COVID-19

“…Computational fluid dynamics has been used in many studies to investigate aerosol transport in outdoor conditions, 14 indoor conditions such as hospitals, 6,15 and even inside the human airway system with good agreement with the experimental data. 16,17 During the COVID-19 pandemic, significant efforts have been made to develop computational fluid dynamics models of the human sneeze, 18 investigate mask mechanics, 19 and study aerosol transport and air flow in different environments and conditions such as aircrafts, 20 vehicular cabins, 1 urinals and toilets, 21,22 public spaces, 23 and indoor spaces. 24,25 Despite these efforts, to the authors’ knowledge, no studies have investigated aerosol transport in a classroom environment although classroom sizes, the air conditioning layout, and aerosol source distribution are characteristically different than hospital care units and other indoor spaces discussed in the literature.…”

Extended lifetime of respiratory droplets in a turbulent vapour puff and its implications on airborne disease transmission

“…However, such direct numerical simulations are highly nontrivial, too. It has been attempted with Euler-Lagrangian approaches with Reynolds-averaged Navier-Stokes (RANS) approximations for a single droplet [46], for multiple droplets [47][48][49] and large eddy simulations (LES) [50], which however are insufficient to properly resolve the small scales of the mixing process, which are crucial for the droplet evaporation. Also temperature and humidity fields are not fully coupled, which however determine the evaporation rate and thus the lifetime of the droplets and are essential to properly describe their collective effects.…”

The role of computational fluid dynamics tools on investigation of pathogen transmission: Prevention and control

“…Small droplets were diluted in the air with million particles which may cause diseases within 6 m in theory. Moreover, in Busco et al (2020) research work, the sneezing zone which may contain virus carriers like droplets or aerosols was modeled by using CFD method. It was proved in this investigation that the biomechanics of sneezing can be predicted by the signal generated from contractions or relaxations of head muscles; Dbouk and Drikakis (2020a) analyzed the effect of the wind speed on the transmission of coughing droplets and found 2 m social distance may not sufficiently prevent pathogen transmission.…”