Transition laminaire : tourbillons de Taylor entre cylindres coaxiaux tournants en présence de particules sphériques rigides

Abstract : We present a theoretical study of the laminar Taylor vortex flow transition between coaxial rotating cylinders, in presence of spherical rigid particles. For this, we first consider the flow of a pure liquid. Integrating the equation of motion, we determine critical parameters a hydrodynamic field and a rate of growth of the vortices, agreeing with the values furnished by the literature. Applying the same method of integration to the Taylor vortex flow wavy Taylor vortex flow transition, we show a new property of the flow, i.e. a structure, similar to that of non rotating motion of a compressible fluid. The introduction of rigid spherical particles in the flow modifies its hydrodynamic field and its rheological behaviour. With the spherical harmonics method, proposed by LAMB, we then calculate the perburbation brought by the particles to the velocity field of the secondary motion. In the newtonian model (concentration less than 25%), we determine the effect of concentration on the critical angular velocity of the inner cylinder, with a microstructure method, proposed by Allen and Kline. For concentrations larger than the critical value above, the suspension is viscoplastic (Bingham model). For that fluid, we complete Graebel's stability study. We precise the critical parameters and we compute the velocity field for diverse values of the Bingham number. So, we show the role on the secondary motion, of Bingham number, which measures the non newtonian effects
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Blaise Nsom Eyenga Ndille. Transition laminaire : tourbillons de Taylor entre cylindres coaxiaux tournants en présence de particules sphériques rigides. Autre [cond-mat.other]. Université Paul Verlaine - Metz, 1987. Français. ⟨NNT : 1987METZ011S⟩. ⟨tel-01775725⟩

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