Self‐similar breakup of viscoelastic thread for droplet formation in flow‐focusing devices

The self‐similarity of the breakup of viscoelastic dispersed thread for droplet formation in flow‐focusing devices is investigated experimentally. A high‐speed camera is used to capture the evolution and angles of the cone‐shaped liquid‐liquid interface. The self‐similar profiles for the liquid‐liquid interface are obtained by normalizing the interface with the minimum width of the dispersed thread. The breakup of the dispersed thread transfers from a self‐similar power law scaling stage with an exponent of 0.36 to a self‐similar exponential scaling stage. The asymptotic cone angles prior to final breakup are consistent with the value of 125.5° and 151°, respectively. The viscoelasticity inhibits the development of finite‐time singularity for the breakup of the liquid‐liquid interface at microscale, similar to the capillary breakup at macroscale. The results demonstrate that the breakup of the viscoelastic dispersed thread for droplet formation exhibits self‐similarity at microscale.