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Spread of Virus in a Classroom - scSTREAM

Spread of Virus in a Classroom - scSTREAM

Picture 1: Classroom Model
This guest post on Innovation Intelligence was written by Nari Yoon, CFD Engineer at Cradle North America. sc/Tetra and scSTREAM for CFD analysis, both developed by Software Cradle.

Sigh—the sweetest two-month vacation just whizzed by like a bullet, and school is back in session, with all the excitement and exhilaration of new beginnings. And guess what else? Flu season is on its way!

Some might have heard that one student with the flu could infect an entire classroom of children. While this sounds scary, it appears to be true. According to the New York State Department of Health, students within three feet of the infected student can “easily be infected” by inhaling airborne droplets. How is that possible? How fast do the droplets travel and how wide do they spread over the class?

Simulation Model

Figure 2: Simulation Model and Conditions.

We decided to test the flu virus spread with our tool of choice, computational fluid dynamics (CFD) simulation
A poor sick student was seated in the middle of the classroom, coughing and sneezing every 10 seconds. Diameters of 10 µm, 5 µm, and 1 µm droplets at a speed of 30, 45, and 100 miles per hour, respectively, were expelled.Unfortunately, the subject did not bother to cover his mouth in the simulation. Having the previously established steady-state flow as an initial condition, transient analysis was run.


Figure 4: Velocity Distribution at breathing level.
The figure below shows the estimated transmission of the cough series. The students with red color become very susceptible to flu, and the ones with yellow become moderately susceptible. In our result, it took only five minutes for most of the students to be exposed to the germs. (Maybe he coughed too often!) If the sick student were seated at the far left, from which location the flow is actively moving to the right, the time lapse to infection would have been even shorter.

Virus Distribution at around head height (between 0.9m and 1.5m)

Red: Concentration > 1           Yellow: Concentration > 0.5
Figure 5: Virus diffusion distribution at 0.9m - 1.5m.

Students exposed to viruses

Red: 100% Probable           Yellow: 50-100% Probable
Figure 6: Potential students exposed to viruses


Using scSTREAM to simulate classroom air flow and virus diffusion shows that more than half of the students in the classroom will be exposed to viruses from a student seated in the middle of the room. Students who do not feel well should be strongly encouraged to stay home untill they feel better


Application Details

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