Theory 23/Mach Number/Respiratory droplets
Droplets Atomise by Mach
The claim
The size distribution of droplets produced by a cough is set by the local Mach number in the airway, so a harder cough produces smaller, farther-travelling droplets.
01Mechanism
Atomisation requires the gas to exceed a velocity at which surface tension can no longer hold a ligament; the ratio sets the resulting drop size.
02Prediction
Drop size should fall as cough Mach rises.
03Refutation
Drop size tracking volume alone would remove velocity.