Modelling vesicle dynamics in extended geometries and in micro-fluidic devices

Abstract : Dynamical behavior and deformation of a single neutrally buoyant suspended vesicle (a closed phospholipid membrane), as a response to external applied flows (simple shear and Poiseuille flows), is studied in the limit of small Reynolds numbers. Unbounded and confined geometries are both considered here. For this purpose we use three-dimensional analytical calculation (small deformation theory) as well as two-dimensional simulations (lattice-Boltzmann and boundary integral methods) to solve the corresponding hydrodynamical equations and to track explicitly the vesicle dynamics. The small deformation theory is used to draw the phase-diagram summarizing the known vesicle dynamical regimes (tank-treading, tumbling and vacillating-breathing), under shear flow. Impact of varying controlling parameters on the evolution of various quantities characterizing each vesicle dynamical regime is reported. We present also how we adapted the lattice Boltzmann method to simulate dynamics of vesicles in confined geometries (e.g. a micro-channel). As benchmarkings, the vesicle equilibrium shapes in a fluid at rest are recovered together with dynamical behavior of a vesicle under simple shear flow - tank-treading -. The effect of confinement on the vesicle dynamics is investigated. Lateral migration of a vesicle placed in unbounded and semi-bounded Poiseuille flow is investigated using the boundary integral method simulations. In the unbounded geometry we find that the nonlinear character of the Poiseuille flow, together with the vesicle deformability, causes a lateral migration of the vesicles towards the flow centerline. In the presence of a bounding wall an additional lift force appears. In this situation we investigate the interplay between the wall- and the Poiseuille flow curvature- induced lift forces. A similarity law for the lateral migration velocity (as a function of relevant structural and flow parameters) that is consistent with experimental results is proposed.
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Contributor : Badr Kaoui <>
Submitted on : Saturday, February 6, 2010 - 8:29:28 PM
Last modification on : Tuesday, September 11, 2018 - 11:00:02 AM
Long-term archiving on : Friday, June 18, 2010 - 7:18:01 PM

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Badr Kaoui. Modelling vesicle dynamics in extended geometries and in micro-fluidic devices. Biological Physics [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2009. English. ⟨tel-00453963⟩

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