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Instabilités de cisaillement dans l'écoulement concentrique de deux fluides miscibles

Abstract : In this report, experiments of shear instabilities in a co-current and coreannular flow of two miscible fluids are presented. The two fluids have the same density but the annular fluid has a higher viscosity than the core fluid. Two control parameters have been used, the Reynolds number and the core fluid radius. We have always obtained an unstable flow and two instability patterns have been observed : pearls and mushrooms. We have built the diagram of occurrence of the patterns in the map of the two control parameters. For mushroom patterns, and for some values of control parameters, instabilities appear near the inlet and exhibit a thin spectral width. This behavior might be a signature of a transition between convective and absolute instabilities. We have tried to characterize the convective or absolute nature of the system with experimental measurements, such as frequency forcing experiments. Our experimental results agree partly with numerical simulations, and reasonably well with a longwave linear stability analysis.
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https://tel.archives-ouvertes.fr/tel-00276589
Contributor : Marguerite d'Olce <>
Submitted on : Wednesday, April 30, 2008 - 1:06:53 PM
Last modification on : Monday, December 14, 2020 - 9:52:15 AM
Long-term archiving on: : Friday, September 28, 2012 - 2:20:09 PM

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  • HAL Id : tel-00276589, version 1

Citation

Marguerite d'Olce. Instabilités de cisaillement dans l'écoulement concentrique de deux fluides miscibles. Dynamique des Fluides [physics.flu-dyn]. Université Pierre et Marie Curie - Paris VI, 2008. Français. ⟨tel-00276589⟩

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