The COVID-19 pandemic is caused by the coronavirus SARS-CoV-2. There is evidence that COVID-19 can be spread via virus-carrying aerosols. One example of this is an outbreak in a restaurant in Guangzhou, China, where an asymptomatic COVID-19 patient caused the infection of eight people, both at the same and at adjacent tables. However, the detailed physical processes and pathways involved in such an aerosol transmission are not well understood so far. An improved understanding could, for example, explain why some people became infected while others within the same area did not, or which role ventilation and air conditioning played in virus transmission.
Jiarong Hong and colleagues, University of Minnesota, Minneapolis, USA, have performed a systematic computational fluid dynamics-based investigation of indoor airflow and the associated aerosol transport in this specific restaurant setting in Guangzhou. The team used so-called large eddy simulations (LES) and other numerical methods to simulate processes such as turbulence, flow–aerosol interplay, thermal effects, and the filtration effect of air conditioners. This allowed them to simulate a realistic case of aerosol transmission and test whether predicted infection risks agree with the observed patterns.
The results show a remarkable agreement between regions of high aerosol exposure and the reported infections within the restaurant. According to the researchers, this provides strong evidence of airborne transmission in this outbreak. Based on flow structure analysis and tracing back aerosol movements, the team also found two possible transmission pathways that might be overlooked by existing protective efforts. These pathways are the transmission caused by aerosols rising from beneath a table and transmission due to aerosols associated with the limited filtration efficiency of air conditioners.
- Simulation-based study of COVID-19 outbreak associated with air-conditioning in a restaurant,
Han Liu, Sida He, Lian Shen, Jiarong Hong,
Phys. Fluids 2021, 33, 023301.
https://doi.org/10.1063/5.0040188
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