Beyond the well-mixed room Respiratory puffs and jets
PROFESSOR: So while I've argued that there are many ways in which a room can become well mixed, hopefully well enough to apply our well mixed criterion for airborne transmission through long range aerosols, there is one very important way in which the transmission problem is never well mixed. And that is taking into account the source of the particles, which is the exhaling of an infected individual which leads to a very high concentration of particles leaving the mouth, which then ends up being dispersed throughout the room. And there is a sort of space and time dependence of that process which we must consider in looking at other possibilities of transmission than just the well mixed background air. So in particular, I've already indicated that the flows generated by breathing tend to be at higher enough Reynolds number to generate turbulence. And in particular, they generate a turbulent jet which ends up taking the form of a cone. Not perfectly but approximatel...