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Ecoulements de fluides complexes dans des canaux sub-microniques

Abstract : Rheology of high molecular weight polymer solutions at submicroscale is investigated, with a particular emphasis on the wall slip characterization. Our approach is to measure the velocity of a pressure-driven flow in sub-microchannels in order to determine an effective viscosity of fluids. We have been using fluorescence photobleaching as a non-invasive technique to evaluate the velocity of a pressure-driven flow in 175 to 4000 nm high channels. A striking reduction of the effective viscosity is observed with the confinement, as compared to the bulk one. Direct measurement of slip velocity in microchannels is performed, using z-resolved micro-Particle Image Velocimetry (PIV). This study enables to draw two important conclusions, which have never been experimentally demonstrated. Slippage of polymer solutions in the semi-dilute unentangled regime is greatly reduced by confinement. A distinction of bulk and surface phenomena seems no longer valid at the submicroscale. This experimental method is also adapted to the study of surfactant solutions flows at the submicroscale.
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https://tel.archives-ouvertes.fr/tel-00820571
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Submitted on : Monday, May 6, 2013 - 10:20:26 AM
Last modification on : Tuesday, December 7, 2021 - 2:06:02 PM

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  • HAL Id : tel-00820571, version 1

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Amandine Cuenca. Ecoulements de fluides complexes dans des canaux sub-microniques. Chimie-Physique [physics.chem-ph]. Université Bordeaux 1 Sciences et Technologie; Université Sciences et Technologies - Bordeaux I, 2012. Français. ⟨tel-00820571⟩

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