Nanoliter-Droplet Breakup in Confined T-Shaped Junctions
Nanoliter-droplet breakup in either symmetrically or asymmetrically confined T-shaped junctions is experimentally studied. The critical condition with which nanoliter droplets will break equally is theoretically analyzed based on the pressure-driven mechanism. The scaling analysis is experimentally confirmed, implying that the droplet breakup in a confined T-shaped junction is a pressure-driven process when the capillary number is less than ∼0.1. A semi-empirical correlation is obtained for predicting the equal breakup in symmetric T-shaped junctions. The critical condition is found to be dependent on the initial droplet length, channel depth and capillary number. Besides the equal breakup of nanoliter droplets, a new droplet breakup pattern, unequal breakup, is observed in the symmetric T-shaped junction. In asymmetric T-shaped junctions the nanoliter-droplet breakup is found to be very difficult.
Keywords: Nanoliter droplet, droplet breakup, confined T-shaped junction, critical condition, microfluidics, capillary number, scaling analysis, interfacial tension, microchannels, flow stability
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