Dynamiques d'aspirations d'interfaces complexes

Abstract : Interested in characterizing biological matters of small volumes (bile, cellular aggregates), we develop a capillary aspiration rheometer. We measure the physical properties of the fluid by its deformation and dynamics in the capillary according to the aspiration power. We first test the system with Newtonian fluids. The critical pressure above which the fluid moves, is linked to the initial interface deformation in the capillary and gives a measurement of the surface tension. The displacement of the fluid corresponding to an imposed pressure gives a measurement of the viscosity . Aspirating at constant pressure or at a variable pressure (linearly with time), we extend the domain of viscosities from 10−3 (bile) to 105 Pa.s (cellular aggregates). This range is adequate for biological material. Then we use the system to characterize different complex fluids. We choose the carbopol which stress follows the Herschel-Bulkley law. The critical pressure gives a measurement of the surface tension and minimal stress of carbopol. Aspirated at a pressure linear in time, the carbopol moves at constant velocity and we measure its rheological parameters. Finally, we aspirate cellular aggregates with viscoelastic properties. The aspiration at constant pressure gives a measurement of aggregates viscosity at large times, while the aspiration at variable pressure gives a measurement of the aggregates elasticity
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Submitted on : Thursday, May 24, 2012 - 2:22:54 PM
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Mélanie Durth. Dynamiques d'aspirations d'interfaces complexes. Mécanique des fluides [physics.class-ph]. Ecole Polytechnique X; Université de Séville, 2012. Français. ⟨pastel-00700999⟩

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