Size prediction of drops formed by dripping at a micro T-junction in liquid-liquid mixing

In the present work, the formation of liquid drops by dripping at a micro-scale T-junction with a square cross-section (90 × 90 μm2) was examined. The drop formation process consists of three stages: X-Y and X-growth stages and a detachment stage. In the X-Y growth stage, the tip of the disperse phase grows both in the longitudinal (X) and lateral (Y) directions to form a bulged shape until a maximum value of Y is reached. Then, in the X-growth stage, the bulged part continues to grow but only in X-direction, followed by the detachment stage to be separated out a single drop through a rapid necking process. The entire process is repeated at regular intervals. The volume of the drop is determined by the Y-directional size of the bulged part at the end of the X-growth stage (SE) and the detaching time (ΔtDetach). Based on the measurement and a simple scale analysis, a correlation to represent the drop size was proposed with the flow rates and fluid properties taken as parameters, and physical interpretations on the correlation were provided as well.