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Fragmentation et coalescence dans les fluides

Abstract : The destabilisation and fragmentation of liquid systems into thin layers frequently occur in many natural as well as industrial processes. This experimental study is devoted to the description, understanding and to the prediction of the mechanisms of instabilities and drop formation.

The first study deals with the fragmentation of a thin fluid layer which freely falls into a Hele-Shaw cell. Mobile contact angles induce different pressures at the interface level and then induce a pressure gradient within the fluid, which favours instability. A linear stability analysis correctly predicts the growth rates and shows the existence of a plateau in the dispersion relation.

The second one is an analysis of drop deformation and break-up within a jet flow. We show that deformation occurs for a particular critical Weber number. We offer a model for the description of the formation and of the ensuing growth of the bag, called bag-breakup.

The third study is about the impact of a drop on a solid of comparable size. We show that the drop gets deform into a liquid sheet surrounded by a rim. We show how the development of the liquid sheet depends on the critical Weber number contrary to its dynamical evolution. We offer a model which correctly predicts the sheet size as well as that of the esulting drops.

A fourth study is devoted to foam coarsening. We show a new experimental device of foam wind tunnel. We compare the traditional experimental devices with ours. We also show an experimental
evidence of von Neumann's law.
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Submitted on : Wednesday, February 27, 2008 - 11:14:03 AM
Last modification on : Thursday, January 23, 2020 - 6:22:06 PM
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  • HAL Id : tel-00259235, version 1

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Benjamin Bossa. Fragmentation et coalescence dans les fluides. Dynamique des Fluides [physics.flu-dyn]. Université de Provence - Aix-Marseille I, 2007. Français. ⟨tel-00259235⟩

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