Droplet breakup

in collaboration with Alexander Leshansky and Shariar Afkhami
We perform experimental studies of droplet breakup in microfluidic T-junctions in a range of capillary numbers lying between 4.10−4 and 2.10−1 and for two viscosity ratios of the fluids forming the dispersed and continuous phases. The present paper extends the range of capillary numbers explored by previous investigators by two orders of magnitude.We single out two different regimes of breakup. In a first regime, a gap exists between the droplet and the wall before breakup occurs. In this case, the breakup process agrees well with the analytical theory of Leshansky and Pismen [Phys. Fluids 21, 023303 (2009)]. In a second regime, droplets keep obstructing the T-junction before breakup. Using physical arguments, we introduce a critical droplet extension for describing the breakup process in this case. This regime has been modeled by A. Leshansky considering a geometrical construction together with a lubrication approach. The numerical simulations provided by S. Afkhami are in agreement with the model, together with the experimental results.

Jullien et al., Phys of Fluids 2009
Afkhami et al. Phys. Rev. Lett., 2012
Obstructed breakup regime :

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