Simulation de globules rouges modèles et analyse analytique de modèles de suspensions très concentrées

Abstract : The principal objective of this thesis is devoted to study the dynamics and rheology of a suspension of dense particles which behave as complex fluids. The first part of this thesis is dedicated to the study of the deformation, the dynamic behavior and rheology of a single neutrally buoyant suspended vesicle (a closed phospholipid membrane), as a response to external applied flows (simple shear and confined Poiseuille flows), is studied in the limit of small Reynolds. The study based on numerical simulations using the boundary integral method. This study is inspired by the behavior of red blood cells in the microvasculature. Our study is then dedicated on the effects of confinement and capillary number on the shape, the dynamic behavior and the effective viscosity of a vesicles suspension. We have shown that for rigid membranes (small capillary number) may be exist other shapes parachute and slipper, these shapes are : (i) Centered Snaking, (ii) Off-Centered Snaking and (iii) Peanut-shaped. Equally, we examined the influence of viscosity contrast on the dynamics and rheology of a vesicle. We have shown that there is a phase of "coexistence" between the slipper and parachute shape. The coexistence of shapes seems to be supported by experiments, though a systematic experimental study is lacking. In the second part of this thesis, we proposed an analytical model and a numerical study for study the dynamics and rheology properties of a rigid particles suspended in a confined Poiseuille flow. The flow rate, the dissipation and the apparent viscosity are studied as a function of the underlying structure. Equally, the numerical study is in good qualitative agreement with the analytical theory considering long plates. The numerical study is based on a fluid dynamic particle method where the particles are represented by a scalar field having high viscosity inside.
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Najim Tahiri. Simulation de globules rouges modèles et analyse analytique de modèles de suspensions très concentrées. Hématologie. Université de Grenoble, 2013. Français. ⟨NNT : 2013GRENY022⟩. ⟨tel-01469938⟩

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