Using laser flow visualization to display this is pretty pathetic. Nonetheless I see a karman vortex street. Which means it’s time to do some math to expose this! https://twitter.com/ingrahamangle/status/1265096356135342083

Karman vortex streets occur at a Reynolds number defined by Re=UL/ν where U is the free steam velocity, L is characteristic, and ν is kinematic viscosity.

So here we have ν = 1.5111x10^-5 kg/(m*s) assuming this was done at room temperature at 1atm.

We’ll assume this was done in a rather typical setting. Maybe 6 feet for the characteristic length? Probably less.

I guess we can round down. 1.5m.

And then we’ll use the free stream velocity of a cough. 22.5 m/s, on average.

So we get a Reynolds number of 2233472. You cannot see those vortex patterns from this scenario at that Reynold's number. So this is faked. Debunked. Bullshit.

The characteristic length would have to be .00067 m, or 2/100th of a foot, far smaller than even that vortex pattern, to get our calculation within the realm of karman vortex street reynold's numbers.

now for some possible explanations about how they did this. they either used a very low cough velocity-- far lower than the actual velocity of a cough, to create this pretty swirly patterns. OR. they used interference.

flow instabilities always dissipate outwards. they're fractal in nature. which means that this right half of the picture is moving the wrong direction.

but doesn't that prove their point?! if the velocity is faster, imagine how much further the cough would spread!? true. but this is a transitional instability. flow is still transitional. there is not yet chaotic flow. when you cough, you're just spreading stuff out everywhere.

you aren't going to inhale someone's vortex of germs from them coughing. that air is traveling so fast, you can barely catch it on video using methods similar to laser visualization. look what it looks like when a proper scientist does this.