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Occlusions pulmonaires, entropion oculaire et anévrismes : une approche physique en physiologie

Abstract : This thesis deals with three physiological issues involving liquid flows and, for two of them, fluid-structure interactions. Each problem is reduced to an experimental set-up respecting its main mechanical and physical properties.

Liquid plugs can resist the air flow in the lungs. Those occlusions result sometimes from the capillary instability. We show that this instability is affected, and sometimes suppressed, by gravity, even at low Bond number : only the smallest airways develop plugs across their lumen. The final stage of the growing of the plugs leads to a singularity specific to the tubular geometry. We develop scaling laws in order to understand it.

The entropion is the turning inward of the border of the eyelid against the eyeball. Previous modelings of the eyelid assumed it was rigid. We study the importance of its elasticity on the coating of the cornea by a tear film. A Landau-Levich-type model is considered. We then look at the possible inversion of the eyelid.

An abdominal aortic aneurysm (AAA) is a locally swollen region of the main artery of the human body. We study experimentally, numerically and theoretically the response of an elastic tube submitted to a pulsatile heart-like flow. On the timescale of one cardiac cycle, we distinguish between two different modes of deformation : the tube can either dilate in a synchronous way on each cycle, or propagate deformation waves. We explain this transition both with a model of elastic waves and by considering the time required to reach equilibrium in the membrane. On very long timescales compared to the cardiac cycle, a windkessel model show a critical flowrate above which the tube grows and develops an "aneurysm". The numerical simulations allow us to couple both the waves and this aneurysm development : they show very interesting issues concerning the preferential location of an aneurysm.
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Contributor : Virginie Duclaux <>
Submitted on : Monday, February 12, 2007 - 11:12:44 PM
Last modification on : Friday, October 23, 2020 - 4:35:15 PM
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Virginie Duclaux. Occlusions pulmonaires, entropion oculaire et anévrismes : une approche physique en physiologie. Biophysique [physics.bio-ph]. Université de Provence - Aix-Marseille I, 2006. Français. ⟨tel-00130610⟩

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