As winter closes more and more indoors and Omigron spreads, scientists are returning to the study of the dynamics of our breathing droplets spreading in space. But developing a model that can predict the behavior of particles from 1 micrometer to 1,000 micrometers is particularly challenging.
Researchers have compared the scattering of cough drops with people climbing stairs.
At AIP Advance, Hongping Wang and his team from the Institute of Engineering and the School of Engineering at the Chinese Academy of Sciences in Beijing provide models showing how the droplets move from the toy through the water tunnel. The tunnel took different slopes, following a man up and down the stairs.
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“There are two different forms of droplet scattering due to different flows,” Wang said.
Toys, 3D printing materials with white resin, each tilted at different angles according to our natural inclination as we climbed and descended the stairs.
The researchers placed glass microspheres in the water tunnel in addition to the toy. When illuminated by light rays, the microspheres visualized the flow of motion in the water behind the toys. This flow field was studied using a technique called particle image velocity measurement.
In computer simulations, particles moving lower than the head and towards the ground “caught” in the flow of water around each toy and moved further and further down. As for the particles above the head, they move horizontally and for relatively long distances, emitting from the surface of the head.
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On the ladder, the particles piled up below the shoulder and moved down a little distance.
In descent simulation, particles scattered over the head were carried over long distances.
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“The biggest challenge is how to use the particles in the water to simulate the droplets in the air.”
Now, researchers plan to study particle behavior, 3D, and experimental conditions when coughing while walking.