الفهرس 
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Abstract
This thesis aims to study the thermophoresis and photophoresis phenomena in the micropolar fluid for cylindrical particles. where micropolar fluids are fluids with microstructure. They belong to a class of fluids with non-symmetric stress tensor that we shall call polar fluids Physically, micropolar fluids may represent fluids consisting of rigid, randomly oriented (or spherical) particles suspended in a viscous medium, where the deformation of fluid particles is ignored. Moreover, it is elegant and not too complicated, in other words, manageable to both mathematicians who study its theory and physicists and engineers who apply it. Although, many research studies are published and concerned with studying the behavior of these fluids in various cases, however, there are many aspects and cases regarding the behavior of such fluids in the presence of some effects such as thermophoresis effects that need more investigations and clarifications. This is done by studying the thermophoretic motion of an aerosol cylindrical particle embedded in a gaseous micropolar fluid in the presence of a uniformly temperature gradient in the direction perpendicular to its axis is investigated. The following assumptions are made: the dissipation function of mechanical energy is neglected; Péclet and Reynolds numbers are small, and the Knudsen number is supposed to be small such that the fluid flow can be described by a continuum model. The thermal stress slip is considered into the formulation with the frictional and creeping slips. The thermophoretic migration velocity of the particle is obtained in a closed form. The effect of micropolarity parameter on the motion of the particle is discussed and compared with the limiting case of the classical viscous fluid. It is also being studied the photophoretic motion of an aerosol cylindrical particle embedded in a gaseous micropolar fluid subject to an intense light beam is analytically treated. The Knudsen number is assumed to be suitably small so that the fluid motion is described by a near-continuum slip-flow model. The steady heat equations inside the particle and in the surrounding micropolar gaseous medium are solved under the assumptions of small Péclet number. The thermal stress slip is considered with the frictional and creeping slips. An analytic expression for the photophoretic migration velocity of the cylindrical particle is obtained in terms of thermal and micropolarity parameters and compared with the limiting case of the classical viscous fluid and also the thermophoresis of a circular cylindrical particle bearing a chemical reaction embedded in a gaseous micropolar fluid is investigated when there is a uniform temperature gradient in the direction perpendicular to its axis is investigated. The appropriate equations that govern the heat conductions distributions inside the particle and fluid and the micropolar fluid motion are analytically solved. The thermophoretic velocity of the particle is found as a function of the relevant physical parameters. It is found that when the composition-dependent factor of the chemical reaction does not depend on position, the thermophoretic velocity is diminished with the endothermic and augmented as exothermic reactions. In the case, when this factor is a function of position, the particle velocity can deflect from the direction of the imposed temperature gradient. The results compared with the limiting case of the classical viscous fluid.