Airborne and aerosol pathogen transmission modeling of respiratory events in buildings: An overview of computational fluid dynamics

Abstract

Pathogen droplets released from respiratory events are the primary means of dispersion and transmission of the recent pandemic of COVID-19. Computational fluid dynamics (CFD) has been widely employed as a fast, reliable, and inexpensive technique to support decision-making and envisage mitigatory protocols. Nonetheless, the airborne pathogen droplet CFD modeling encounters its limitations in the oversimplification of involved physics and the intensive computational demand. Moreover, uncertainties in the collected clinical data required to simulate airborne and aerosol transport such as droplets’ initial velocities, tempo-spatial profiles, release angle, and size distributions are broadly reported in the literature. Furthermore, there is a noticeable inconsistency around these collected data amongst many reported studies. Hence, this study aims to review the capabilities and limitations associated with CFD modeling. Setting the CFD models needs experimental data of respiratory flows such as velocity, particle size, and number distribution. Hence, we will also briefly review the experimental techniques used to measure the characteristics of airborne pathogen droplet transmissions together with their limitations and reported uncertainties. Moreover, the relevant clinical data related to pathogen transmission needed for postprocessing of CFD data and translating them to safety measures will also be reviewed. Eventually, we scrutinize the uncertainty and inconsistency of the existing clinical data available for airborne pathogen CFD analysis to pave a pathway toward future studies ensuing these identified gaps and limitations.

Air curtain as a SARS-CoV-2 spreading mitigation method in a small aircraft cabin

“…The following approach was utilized numerous times when dealing with droplet dispersion problems in confined spaces, including aircraft cabins. 8,9,54,61…”

“…The following approach was utilized numerous times when dealing with droplet dispersion problems in confined spaces, including aircraft cabins. 8,9,54,61 The force balance equation of particle in the Lagrangian reference frame is expressed in equation ( 5). It equates the particle inertia with the significant forces acting on the particle (theory relies on Newton's second law)drag, buoyancy, and others:…”

Ventilation strategies to reduce airborne transmission of viruses in classrooms: A systematic review of scientific literature

“…For the investigation of airborne transmission between people, it is necessary to insert computational thermal manikin(s) in the space geometry and model the dispersion of respiratory droplets and pathogens released by respiratory events [ 33 ]. For this type of applications, it is therefore necessary to carry out multi-phase simulations, where the transport and the trajectories of the pathogen droplets can be described with both a Lagrangian and Eulerian approach [ 34 ]. Various methods can be found in the literature by which the risk of cross-infection of different airflow patterns has been investigated.…”

Bioaerosol distribution characteristics and potential SARS-CoV-2 infection risk in a multi-compartment dental clinic

“…According to Morawska [ 48 ], the evaporation time of 1 μm particles takes only a few milliseconds. In addition to the extremely short evaporation time, the small particles hardly rupture [ 49 , 50 ]. Thus, the effects of rupture and evaporation were not considered in the CFD simulations because of the small size of the selected bioaerosols.…”