I will discuss the formation and breakup of liquid sprays with an emphasis on the underlying instability mechanisms and their consequences for droplet-size statistics.
I will mainly focus on medical sprays (e.g., nose sprays or asthma medication) formed by collections of Rayleigh jets. In a simplified one-dimensional jet geometry we first study the breakup langth of a jet and subsequently resolve the full coalescence dynamics of droplets and ligaments and show how vacuum can be used to suppress the Kelvin–Helmholtz instability that leads to the characteristic fanning out of sprays.
If time permits, I will also discuss agricultural sprays, where Squire–type shear instabilities on a thin liquid sheet set a characteristic ligament scale that can be shown to set the droplet-size distribution in a way that is quantitatively captured by scaling laws in terms of Weber number and density ratio.
