Quote:
Originally Posted by tcar
Smoke does not behave like 'droplets'.
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I believe they used a fog machine, not "smoke". Speaking of which, I do wonder if smoking can help here.
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We use a recreational fog/smoke machine to generate tracer particles for visualizing the expelled respiratory jets, using a liquid mixture of distilled water (4 parts) and glycerin (1 part).
The resulting “fog” or “smoke” is visible in the right panel of Fig. 1 and is composed of microscopic droplets of the vaporized liquid mixture. These are comparable in size to the smallest droplets expelled in a cough jet (∼1 µm–10 µm). We estimate that the fog droplets are less than 10 µm in diameter, based on Stokes’ law and our observation that
they could remain suspended for up to 3 min in completely still air with no perceptible settling. The laser source used to generate the visualization sheet is an off-the-shelf 5 mW green laser pointer with 532 nm wavelength. A plane vertical sheet is created by passing the laser beam through a thin cylindrical rod (diameter 5 mm) made of borosilicate glass.