In Liquid Physics, researchers report the use of advanced simulation methods to capture the complex currents when the cold airflow of air conditioners interacts with the hot plume of a dining table and the transport of virus-laden particles within such streams. Scheme of the flow and particle transport, which highlights the two transport routes within the entire restaurant. Mannequins show where customers sit. Credit: Han Liu
More preventative measures, such as shielding under tables and improving the filtering efficiency of air conditioners, may expose COVID-19 inside restaurants with air conditioning.
The detailed physical processes and pathways involved in the transmission of COVID-19 are not yet well understood. Researchers have decided to use advanced fluid dynamics tools for calculations on supercomputers to deepen the transmission and provide a quantitative assessment of how different environmental factors affect the transmission pathways and risk of infection in the air.
A restaurant outbreak in China has been widely reported as strong evidence of COVID-19 transmission by airflow. But it lacked a detailed investigation into exactly how transfer took place.
Why did some people become infected while others did not live in the same area? What specific role did ventilation and air conditioning play in the transmission of diseases? If you investigate these questions, you can develop more accurate preventative measures to improve our safety.
In Physics of liquids, of AIP Publishing, Jiarong Hong and colleagues at the University of Minnesota report using advanced simulation methods to capture the complex currents when the cold airflow of air conditioners interacts with the hot plume of a dining table and the transport of virus-laden particles such flow.
“Our simulation captures various physical factors, including turbulent airflow, thermal effect, aerosol transport in turbulence, limited filtration efficiency of air conditioners, as well as the intricate geometry of space, all of which play a role in airborne transmission,” said Hong.
Although many computer simulation studies have been done on the transmission of COVID-19 in the air, few link the prediction of a high confidence simulation of calculation of the fluid dynamics with the actual infection outbreaks reported by contact detection.
This work is the first realistic case to be simulated and directly linked to the prediction of simulation.
“This has been made possible by advanced computational tools used in our simulation, which can capture the complex currents and aerosol transport and other multiphysics factors involved in a realistic environment,” Hong said.
The results show a remarkable direct link between regions with a high aerosol exposure index and the reported infection patterns in the restaurant, which strongly supports airborne transmission in this outbreak.
Using flow structure analysis and aerosol trace trace, the researchers further identified two potential transmission pathways that are currently being overlooked: the transmission caused by aerosols rising under a table and transmission due to the re-entry of aerosols associated with a limited filtering efficiency of air conditioners.
“Our work highlights the need for more preventative measures, such as better screening under the table and improving the filtration efficiency of air conditioners,” Hong said. “More importantly, our research demonstrates the capability and value of high-reliability computer simulation tools for airborne infection risks and the development of effective preventative measures.”
Reference: “Simulation-Based Study of COVID-19 Outbreaks Related to Air Conditioning in a Restaurant” by Han Liu, Sida He, Lian Shen, and Jiarong Hong, February 9, 2021, Physics of liquids.
DOI: 10.1063 / 5.0040188