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Generation, flow and manipulation of a microfoam

Abstract : This thesis is on the edge of two domains: foam rheology and microfluidics. We present how to create a foam in a microfluidic channel system with a typical smallest dimension for the bubbles of 100 μm and we study its flow. After recalling the state of the art in two-phase microfluidics and 2D foam flows, we present the ensemble of experimental techniques that allow to produce the channel system and image the resulting flow. Then, we investigate microfluidic foam generation using the flow focusing technique. We measure the dependence of the foam properties (liquid fraction, topology) on the input parameters and geometry. We show that the rheology of the foam flow is very non-linear. The pressure-flow rate relation notably presents a threshold, a power law, and discontinuities related to topology transitions. We bring into evidence a retroactive effect of the flow in the channel on foam formation, that leads to a rich dynamical behaviour. We notably find an oscillation between different topologies that we relate to an instability that can either be advected, stationary or absolute. We eventually investigate a method to apply forces on the two-phase flow by ultrasound, to manipulate the foam externally.
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https://tel.archives-ouvertes.fr/tel-00192819
Contributor : Jan-Paul Raven <>
Submitted on : Thursday, November 29, 2007 - 2:42:09 PM
Last modification on : Tuesday, September 11, 2018 - 11:00:02 AM
Long-term archiving on: : Monday, June 27, 2011 - 5:32:18 PM

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  • HAL Id : tel-00192819, version 1

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Jan-Paul Raven. Generation, flow and manipulation of a microfoam. Fluid Dynamics [physics.flu-dyn]. Université Joseph-Fourier - Grenoble I, 2007. English. ⟨tel-00192819⟩

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