A stress‐balance‐based critical Weber number for droplets and bubbles

Abstract Predicting droplet and bubble breakup in turbulent flows is critical for optimizing multiphase flow processes such as emulsification and atomization. Traditional models based on a fixed critical Weber number () may not capture interfacial‐stress dominance in low‐viscosity fluids or viscous resistance in high‐viscosity droplets. This investigation provides the first direct, systematic validation of the stress‐balance criterion , obtained by combining Hinze stress scalings in an explicit three‐way force balance, in which the breakup threshold scales linearly with capillary number. This formulation provides a seamless framework applicable to both bubbles and droplets with moderate internal viscosity, and reduces reliance on regime‐specific empirical corrections by linking the breakup threshold directly to intrinsic fluid properties. Validation against experimental and simulation data, including bubbles and droplets, demonstrates good predictive accuracy for viscosity ratio up to at least , providing a generalized approach for turbulent multiphase flows.