Noninertial lateral migration of vesicles in bounded Poiseuille flow

Cross-streamline noninertial migration of a vesicle in a bounded Poiseuille flow is investigated experimentally and numerically. The combined effects of the walls and of the curvature of the velocity profile induce a movement toward the center of the channel. A migration law (as a function of relevant structural and flow parameters) is proposed that is consistent with experimental and numerical results. This similarity law markedly differs from its analog in unbounded geometry. The dependency on the reduced volume nu and viscosity ratio lambda is also discussed. In particular, the migration velocity becomes nonmonotonous as a function of nu beyond a certain lambda. (c) 2008 American Institute of Physics.