The Weber number (We) is most relevant to which mixing/dispersion phenomenon in fluid systems?

Introduction / Context:
The Weber number compares inertial forces to interfacial (surface tension) forces: We = ρ * u^2 * L / σ. It indicates the propensity for drop or bubble breakup in turbulent fields.

Concept / Approach:
When We exceeds a critical value, inertial stresses overcome surface tension, causing a dispersed liquid phase to break into smaller droplets. Thus We is central to predicting drop size in liquid–liquid dispersions and bubble breakup in gas–liquid systems. While it appears in broader mixing discussions, its signature application is liquid-in-liquid dispersion control.

Final Answer:
Dispersion of a liquid into another immiscible liquid (drop breakup)