Dynamique de vésicules sous cisaillement

Abstract

Giant vesicles are deformable lipid membranes enclosing a fluid, with diameters of several microns. They are useful models for the study of biological flows. Their behaviour under shear flow reveals a complex dynamics involving several regimes: stationary tank-treading motion, periodic fliping or tumbling motion, and periodic vacillating-breathing motion. Our experimental study reveals that the deformability of vesicles strongly influences the dynamics. One noticeable feature is a slowing down of the tumbling motion with respect to the shear rate when the latter increases. A semi-phenomonological model including the deformability of objects helps understand the connection between the slowing down of the tumbling motion and a coupling between rotation and deformation. A new vacillating-breathing motion is also predicted and a complex phase diagram can be established.