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Instabilités d'un film liquide en écoulement sur une fibre verticale

Abstract : We consider the instability of a viscous liquid film flowing down a vertical fibre. We explore experimentally the various dynamical regimes arising from the interplay of viscosity, surface tension and inertia. We demonstrate the existence of two different dynamics, the instability being either absolute or convective due to the competition between the capillary Rayleigh-Plateau instability and the advection of the waves by the gravity-induced flow. We obtain a theoretical criterion describing this transition. When the instability is convective, the system behaves as a noise amplifier. We then study the selective spatial response of the film to periodic perturbations at inlet. The destabilisation of the flow leads to the creation of non-linear travelling waves. Those waves are characterised both experimentally and numerically from a non-linear model based on lubrication theory. When viscous and surface tension effects are of the same order, the waves are localised; their particular shape gives rise to attractive or repulsive interactions leading to the formation of bound states. Finally, we focus on the surface tension dominated regime and study the change of dynamics related to the development of recirculation zones in the drops.
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https://tel.archives-ouvertes.fr/tel-00433439
Contributor : Camille Duprat <>
Submitted on : Thursday, November 19, 2009 - 1:22:17 PM
Last modification on : Monday, December 14, 2020 - 9:48:53 AM
Long-term archiving on: : Thursday, June 17, 2010 - 6:57:48 PM

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  • HAL Id : tel-00433439, version 1

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Camille Duprat. Instabilités d'un film liquide en écoulement sur une fibre verticale. Dynamique des Fluides [physics.flu-dyn]. Université Pierre et Marie Curie - Paris VI, 2009. Français. ⟨tel-00433439⟩

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