The variations of breakup and non-breakup regions for ferrofluid microdroplets in T-junctions with a proposed correlation

Lots of attention has been paid to microfluidic and nanofluidic instruments in recent decades. One of the interesting instruments in this field that has attracted scientists is T-junctions. This paper reports an empirical study on the variation of breakup and non-breakup regions for ferrofluid microdroplets in symmetrical T-junctions under an asymmetrical magnetic field in the center of the junction. The asymmetrical magnetic field was generated using a permanent magnet on the right side of the T-junction. During the tests, ferrofluid microdroplets with different lengths and various velocities were entered into the T-junction and were influenced by an asymmetrical magnetic field. Results show that the increment in the magnetic flux density causes a higher possibility of non-breakup for ferrofluid microdroplets. Therefore, the breakup and non-breakup region in the diagram of non-dimensional length versus Ca number shifts upward. On the other hand, it was observed that the increment in Ca number is a key factor in breaking the microdroplets in the T-junction. Finally, a correlation was proposed to predict the breakup and non-breakup region due to different amounts of magnetic flux density and Ca number.