Reducing Particle Exposure and SARS-CoV-2 Risk in Built Environments through Accurate Virtual Twins and Computational Fluid Dynamics

Abstract

The World Health Organization has pointed out that airborne transmission via aerosol particles can be a strong vector for the spread of SARS-CoV-2. Protecting occupants from infectious diseases or harmful particulate matter (PM) in general can be challenging. While experimentally outlining the detailed flow of PM in rooms may require complex setups, computational fluid dynamics (CFD) simulations can provide insights into improving the safety of the built environment and the most effective positioning of air-purifying devices. While previous studies have typically leveraged Reynolds-averaged Navier–Stokes (RANS) approaches for predicting particle propagation, the turbulence length scales accurately captured in these simulations may not be sufficient to provide a realistic spread and the mixing of particles under the effects of forced convection. In this paper, we experimentally validate a Lattice Boltzmann very large eddy simulation (VLES) approach including particle modeling. We also demonstrate how this simulation approach can be used to improve the effectiveness of air filtration devices in realistic office environments.

Predicting Contamination Spread Inside a Hospital Breakroom with Multiple Occupants Using High Fidelity Computational Fluid Dynamics Simulation on a Virtual Twin

“…The coupling between the Lagrangian particle simulator with the flow solver in Pow-erFLOW tracks the trajectory of millions of particles accurately [38,39]. Figure 6 shows an image of droplets transported by cough airflow simulated using the described methodology.…”

“…A Gaussian distribution was selected for modeling the particle size, with a mean of 2.8 µm and a standard deviation σ of 0.5 µm. This distribution was selected based on the methodology developed and used from previous works [38,42]. The size of the droplets ranged from 0.46 µm to 4.9 µm, covering both aerosols and droplets in the study.…”

“…In order to predict the flow from the mouth accurately, fine resolution was added in the mouth region. The selected computational domain was subdivided using a non-conformal mesh of cubic elements into multiple variable resolutions (VRs), and an appropriate resolution was selected for each different region to accurately resolve the flow structures following the methodology described in [38], which showed good agreement with the physical experiment. The finest cell size used in this study was 2 mm.…”

“…A joint venture study with the German institute research Institut für Energie-und Umwelttechnik e. V (IUTA) showed particle/contaminant propagation and risk assessment in closed spaces, including the effect of filtering devices with simulations using the commercial CFD software PowerFLOW TM 6-2021. LBM with the VLES method was experimentally validated to improve the effectiveness of filtration devices in realistic office environments [38]. Such studies highlighted the importance of having an efficient HVAC system with appropriate sizing and settings to generate an airflow pattern that will help mitigate the risks of cross-contamination.…”

Evaluation of Surrogate Aerosol Experiments to Predict Spreading and Removal of Virus-Laden Aerosols

“…However, if this is not feasible, Küpper et al showed that placing APs in the corner of a room is still effective if there is no disturbance for the air flow at the intake and outlet [37]. Aerosol spreading has also been described numerically to spatially resolve aerosol spreading, i.e., for a more precise evaluation of room mixing, prediction of infection risk, or the optimized positioning of filtering devices [38][39][40][41][42][43]. Most of these considerations mainly cover unsteady situations.…”