Theory 34/Weber Number/Pesticide spraying
Droplet Retention Is Weber
The claim
Whether a spray droplet adheres to a leaf or bounces off is set by its Weber number, so finer sprays are not necessarily better for retention.
01Mechanism
Impact outcome depends on the balance of kinetic energy and surface tension; above a threshold, the drop fragments or rebounds.
02Prediction
Retention should peak at an intermediate Weber number.
03Refutation
Retention increasing with finer spray would remove the impact threshold.