Dynamics of non-Newtonian droplet breakup with partial obstruction in microfluidic Y-junction

Dynamics of non-Newtonian droplet (CMC aqueous solution) breakup with partial obstruction in microfluidic Y-junction was visually investigated. Three breakup stages were found: squeezing, transition and pinch-off. The effects of the concentration c of CMC, continuous capillary number Ca c and dispersed phase local capillary number Ca d on droplet breakup were studied. In squeezing stage and transition stage, the breakup process could be promoted by increasing Ca d or decreasing c . The pinch-off stage relied primarily on the surface tension and was almost independent of inertial force and viscous force. For the shear thinning non-Newtonian droplet, the length of the daughter droplet was always linearly stretched with time until breakup and the maximum gap width increased with Ca c , but decreased with the increases of c and Ca d .