Emulsion-Based Single Drop Generation in a Nonconfined System

Single drop generation in a nonconfined system during the dripping regime is studied to evaluate the effect of operating conditions on the formation time and drop size. The drop itself is composed of a water-in-oil emulsion that rises from a nozzle into a stationary aqueous phase. This emulsion is non-Newtonian and undergoes shear-thinning behavior, leading to an important decrease in viscosity upon exposure to shear forces. Its viscosity and shear-thinning level depend on the inner water fraction besides the oil viscosity. The viscosity appears to affect both the formation and detachment stages as opposed to what was reported in the previous literature. The theoretical volume of the detached drop is calculated based on the equilibrium of the forces acting upon the attached drop, in addition to the volume added in the second stage while considering the fraction of the residual drop left attached to the capillary after detachment. This model allowed for the prediction of the dynamic interfacial tension by minimizing the error between the theoretical and the experimental drop volumes.