Droplet breakup in the square microchannel with a short square
constriction to generate slug flow
Droplet breakup in micro-constrictions is an important phenomenon in
industrial applications. This work aimed to investigate the droplet
breakup in the square microchannel with a short square constriction to
generate the slug flow, which drew little attention before. Mechanism
analysis indicated that this breakup process included the
shear-force-dominated, squeezing-force-dominated, and pinch-off stages.
Non-uniform daughter droplets were generated in the constriction with
their interface restricted in the horizontal and perpendicular
directions by the microchannel walls. The average relative deviation of
the daughter droplet size was < 30%, much lower than that for
the breakup with the daughter droplet restricted only in one direction.
An empirical equation with a deviation of < 20% was provided
to show the dependence of the daughter droplet size on the operation
conditions. The comparison results suggested that the different
restriction effects of microchannel wall on daughter droplets led to the
different breakup mechanisms in different constrictions.