A picture showing the flow of air when the window is opened differently in a car with two people. The air becomes stagnant and the longer it is stagnated, the redder it becomes. Comparing the second and third figures in the upper row, it can be seen that the aerosol particles have a low density and do not propagate when two people open a window farther from each other. Thesis capture
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There is a high probability of getting infected if you ride with a person with a novel coronavirus infection (COVID-19, Corona 19). This is because the space inside the car is small and the distance between people is close, so there is a high probability that the droplets from the mouth of Corona 19 patients will be mixed with the aerosol and spread. To reduce the chance of infection, the only option is to open the window and ventilate even if the weather is cold.
Vargis Matai, an assistant professor at the Department of Physics at the University of Massachusetts Amherst, USA, used computational fluid dynamics (CFD), which mathematically analyzes the flow of fluids such as air and water, to simulate the air flow inside and outside the car. The car was modeled after the’Prius’ made by Japanese automobile company Toyota, and it was assumed that in addition to the driver, one passenger sat in the rear seat opposite the driver. The car’s speed was maintained at 80 km/h.
The research team analyzed the air flow inside the car by dividing it into six situations where the window was open. There are a total of 16 cases of opening four windows, but the research team found that when all windows were opened, all windows were closed, only the driver’s window was opened, only the passenger side window was opened, and only the driver’s seat and passenger side windows were opened. , Only when the windows opposite the driver’s seat and the passenger side were opened.
The smoothest air flow was when all windows were opened, and the most congested case was when all the windows were closed and the car’s air circulation system was turned on. When all windows were opened, the hourly air exchange rate (CH) was 250, while when all windows were closed, it was 60 times.
Because the car is designed to be streamlined, the airflow is random. For this reason, unexpected results have also appeared in the internal flow. When the driver’s seat and passenger side windows were open, the ACH was 89 times, not much higher than when all windows were closed. On the other hand, when only the window on the driver’s seat was opened, only the window on the passenger side was opened, and when the window on the opposite side of the driver’s seat and the passenger was opened, the ACH was quite high at about 150.
This result suggests that if you open only two windows and you habitually open the nearest window, the virus can spread more than if you open the other window. In this case, not only is the ACH higher, but because air escapes from the passenger window to the front window, there is a high probability that droplets from the passenger’s mouth will ride through the air before reaching the driver.
“Opening a window in a car is less effective than wearing a mask,” said Matai, an assistant professor who led the study, but it helps prevent pathogens from building up inside the car.
The study was published in the December 4th issue of Science Advance, an international journal.
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