With high-speed camera

formation of ferrofluid droplets in mineral oil was studied in a Y-shaped microchannel with cross section of 400 μm×400 μm. In the system of water-based ferrofluid (EMG 807) as dispersed phase and mineral oil with 4%(mass) surfactant sorbitan lauric acid ester (Span-20) as continuous phase

three types of flow regimes were observed

i.e.

slug

dripping and jetting flows. Study of two-phase flow rates

capillary number of continuous phase and magnetic flux density on droplet size and formation process showed that both two-phase flow rates and magnetic field could regulate droplet size. At constant flow rate of the dispersed phase

droplet size decreased with increasing ratio of two-phase flow rates. The droplet size decreased with the increase of capillary number of continuous phase and magnetic flux density

but increased along with the increase of flow rate of the dispersed phase. A correlation of droplet size was proposed on parameters of two-phase flow rates

capillary number of continuous phase

and magnetic Bond number

which offered accurate prediction with experimental data.