Passive breakups of drops in microfluidic geometries
Résumé
Using two different geometries, rectangular obstacles and asymmetric loops, we investigate the breakup dynamics of deformable objects such as drops and bubbles confined in microfluidic devices. We thoroughly study two distinct flow configurations that depend on whether object-to-object hydrodynamic interactions are allowed. When such interactions are introduced, we find that the volume of the daughter objects created after breakup may solely depends on the geometrical features of the devices and therefore is not affected by the hydrodynamic and physicochemical variables or in contrast may lead to periodical sequences of fragmentation events; these results are in very different from those obtained for non-interacting objects. For both configurations, we provide simple phenomenological models that well capture experimental findings and predict the evolution of the volume of the daughter objects with the controlling dimensionless quantities that are identified. We introduce a mean-field approximation which permits to account for the interactions between objects during breakup and we discuss its conditions of validity.