Splitting behaviors of droplets in fractal tree-shaped microchannels

Droplet splitting in fractal tree-shaped microchannels is studied experimentally in this work. Four flow patterns of droplets splitting in fractal tree-shaped microchannels are distinguished according to the level of bifurcations that all the droplets breakup. The self-similar variation of the droplet pressure and velocity are discussed. And the effect of capillary number and droplet size on the size distribution of daughter and granddaughter droplets are examined quantitatively. The results indicate that the tree-shaped networks with phi = 90 degrees are better than the phi = 120 degrees for the sequential breakup of droplets. Asymmetry in the breakup accumulates as the droplets enter high -level branch channels. Increasing Ca is an effective approach in maintaining the monodispersity of daughter and granddaughter droplets since non-breakup regime is eliminated in the low-levels of branch channels. The per-formance of splitting droplets is deteriorated as the mother droplet size decreases, that increasing inactive branch channels are observed.

Automated summary

This work experimentally studies droplet splitting in fractal tree-shaped microchannels. Four flow patterns of droplet splitting are distinguished based on the level of bifurcations. The self-similar variation of droplet pressure and velocity is discussed, and the quantitative examination of the effect of capillary number and droplet size on daughter and granddaughter droplet size distribution is conducted. The results show that tree-shaped networks with a branching angle of 90 degrees perform better in sequential droplet breakup. Asymmetry in breakup accumulates in high-level branch channels. Increasing the capillary number helps maintain the monodispersity of daughter and granddaughter droplets by eliminating the non-breakup regime in low-level branch channels. The performance of droplet splitting deteriorates as the mother droplet size decreases, with more inactive branch channels observed.