Modeling of droplet breakup in a microfluidic T-shaped junction with a phase-field model

A phase-field method is applied to the modeling of flow and breakup of droplets in a T-shaped junction in the hydrodynamic regime where capillary and viscous stresses dominate over inertial forces, which is characteristic of microfluidic devices. The transport equations are solved numerically in the three-dimensional geometry, and the dependence of the droplet breakup on the flow rates, surface tension and viscosities of the two components is investigated in detail. The model reproduces quite accurately the phase diagram observed in experiments performed with immiscible fluids. The critical capillary number for droplet breakup depends on the viscosity contrast, with a trend which is analogous to that observed for individual isolated droplets in hyperbolic flow.