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Article Dans Une Revue Journal of Fluid Mechanics Année : 2015

Stretching of capsules in an elongation flow, a route to constitutive law

Résumé

Soft bio-microcapsules are drops bounded by a thin elastic shell made of cross-linked proteins. Their shapes and their dynamics in flow depend on their membrane constitutive law characterized by shearing and area-dilatation resistance. The deformations of such capsules are investigated experimentally in planar elongation flows and compared with numerical simulations for three bidimensional models: Skalak, neo-Hookean and generalized Hooke. An original cross-flow microfluidic set-up allows the visualization of the deformed shape in the two perpendicular main fields of view. Whatever the elongation rate, the three semi-axis lengths of the ellipsoid fitting the experimental shape are measured up to 180 % of stretching of the largest axis. The geometrical analysis in the two views is sufficient to determine the constitutive law and the Poisson ratio of the membrane without a preliminary knowledge of the shear elastic modulus Gs. We conclude that the membrane of human serum albumin capsules obeys the generalized Hooke law with a Poisson ratio of 0.4. The shear elastic modulus is then determined by the combination of numerical and experimental variations of the Taylor parameter with the capillary number.
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Dates et versions

hal-01315786 , version 1 (13-05-2016)

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Clement de Loubens, Julien Deschamps, Gwenn Boedec, Marc Leonetti. Stretching of capsules in an elongation flow, a route to constitutive law. Journal of Fluid Mechanics, 2015, 767, pp.R3. ⟨10.1017/jfm.2015.69⟩. ⟨hal-01315786⟩
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