Don't let COVID get the better of you 1 (room with one window)

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What type of experiment is this?

Experimental procedure and explanation:

• The spread of COVID infection has become a severe problem. As a countermeasure, it is necessary to avoid the three Cs (closed space, crowded places, and close-contact settings). We perform an experiment with room ventilation as a way to prevent sealing.
• Using cardboard, make a model of a room 10-cm wide, 10-cm long, and 5-cm high. In addition, a 4-cm wide window was cut in the front wall. A transparent board (a CD case is used in this video) was attached to the ceiling.
• Paper was shredded into small pieces and sprinkled inside the model.
• We applied wind using a fan (a factory fan is used in this video) and observed the movement of the pieces of paper inside.
• You should be ready to collect the pieces of paper that are blown out with a net or using other means so that they do not scatter.
• When wind is applied from the front, the pieces of paper near the window move, but most of the times, the pieces of paper inside do not move. This means that air flow is weak and almost no ventilation is possible.
• Next, when the airflow is applied at a 45° angle, the flow is similarly weak except near the windows, indicating that not much ventilation has been achieved.
• Thus, when there is only one window, we cannot expect much ventilation. If there is only one window, measures such as running an exhaust fan or using a fan to circulate the air inside the room can help to a certain extent.
• In an actual room, the air inside is stirred up when people move about, when there is fluctuation in the wind, or by the mixing and diffusion of flows. Thus, there is a little more ventilation. Simply having one window is not sufficient.
• This experiment can be conducted at home by making a model out of a milk or juice carton and using the transparent lid of a lunch box as a ceiling. We experiment with different window positions and sizes.
• This experimental video was produced with the support of JSPS Grant-in-Aid for Scientific Research 18K03956.

[Keywords]	Ventilation, separation
[Related items]	Don't let COVID get the better of you 2 (room with two windows)
[Reference]	Ryozo Ishiwata and Mitsumasa Nemoto, "The Wondeｒ of Flow" Kodansha Blue Backs, p. 152. Ryozo Ishiwata, "Illustrated Fluid Dynamics Trivia", Natsume Publishing, P68-69.

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