Concentrated phase emulsion with multi-core morphology under shear: A numerical study

Abstract: We numerically study the dynamic behavior under a symmetric shear flow of selected examples of concentrated phase emulsions with multi-core morphology confined within a microfluidic channel. A variety of new nonequilibrium steady states is reported. Under low shear rates, the emulsion is found to exhibit a solid-like behavior, in which cores display a periodic planetary-like motion with approximately equal angular velocity. At higher shear rates two steady states emerge, one in which all inner cores align along the flow and become essentially motionless and a further one in which some cores accumulate near the outer interface and produce a dynamical elliptical-shaped ring chain, reminiscent of a treadmilling-like structure, while others occupy the center of the emulsion. A quantitative description in terms of i) motion of the cores, ii) rate of deformation of the emulsion and iii) structure of the fluid flow within the channel is also provided.