Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification

• Published in: Journal of colloid and interface science 2017-11, Vol.505, p.315-324
• Main Authors: Nabavi, Seyed Ali, Vladisavljević, Goran T., Bandulasena, Monalie V., Arjmandi-Tash, Omid, Manović, Vasilije
• Format: Article
• Language: English
• Subjects: Core-shell droplets; Double emulsions; Dripping regime; Dripping-to-jetting transition; Droplet microfluidics; Glass capillary device; Narrowing jetting; Velocity profile; Volume of fluid–continuum surface force model; Widening jetting
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2017.05.115

[Display omitted] Predicting formation mode of double emulsion drops in microfluidic emulsification is crucial for controlling the drop size and morphology. A three-phase Volume of Fluid-Continuum Surface Force (VOF–CSF) model was developed, validated with analytical solutions, and used to investigate drop formation in different regimes. Experimental investigations were done using a glue-free demountable glass capillary device with a true axisymmetric geometry, capable of readjusting the distance between the two inner capillaries during operation. A non-dimensional parameter (ζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζ>5.7, drops were formed in dripping mode; the widening jetting occurred at 5