A parametric study of droplet deformation through a microfluidic contraction

A numerical parametric study of droplet deformation within an axisymmetric micro-fluidic contraction is performed. The simulations use a transient Volume of Fluid finite volume algorithm and cover parameter ranges representative of micro-sized liquid-liquid systems. We consider two disperse continuous viscosity ratios. When the phases have equal viscosities, the predicted droplet shapes range from short `slugs' constrained by the contraction walls through to long thin `filaments'. When the disperse phase viscosity is lower than that of the continuous phase, capillary waves and other instabilities develop along the droplet surface, leading to more complex shape development and associated fluid dynamics