Browsing by Author "Kouadri, Amar"

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    Analytical solution of non-newtonian nanofluid flows within circular duct under convective boundary condition
    (International Information and Engineering Technology Association, 2021) Tahiri, Antar; Mansouri, Kacem; Rahmani, Kouider; Kouadri, Amar; Douroum, Embarek
    At the outset, this work aims to carried out an analytical investigation of forced convection by establishing a laminar flow into circular duct under convective boundary conditions of the third type for non-Newtonian nanofluid, the fluid containing TiO2 uniformly dispersed in aqueous solution with 0.5wt% of CMC solutions (Carboxymethyl Cellulose) is used as working fluid. The viscous dissipation effects are taken into account, the employed methodology is based on a combination of the Ritz variational approach with the Laplace transformation technique, so the power-law fluids flow model is used to describe the non-Newtonian fluid behavior. The effect of dimensionless parameters such as Biot (Bi), Brinkman (Br), Peclet (Pe) numbers, power-law index (n), and nanoparticles concentration (φ) on the temperature distribution contours and on the examined local Nusselt number. Our results have been compared with those found in the literature in particular the cases of base fluids (φ=0) with and without viscous dissipation effects
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    Ecoulements engendrés par la rotation différentielle de parois d'enceintes cylindriques et coniques
    (2007) Kouadri, Amar
    Ce travail propose une étude numérique de certaines structures d’écoulements secondaires, engendrées par la rotation différentielle des parois d’une enceinte de type rotor-stator cylindrique. Une attention particulière est réservée au phénomène d’éclatement tourbillonnaire, de type bulbe, axisymétrique, stationnaire et stable qui se superpose à l’écoulement de base. Ce phénomène est communément caractérisé par une zone d’écoulement axial inverse, d’extension limitée, précédée par l’existence d’un point d’éclatement sur l’axe de la cavité. La modélisation numérique, en différences finies, a permis sa mise en évidence et sa caractérisation. Dans le cadre d’une tentative de contrôle de l’éclatement, l’étude révèle que la co-rotation différentielle d’un moyeu central, de faible rayon, entraîne la disparition progressive des zones éclatées ; alors que, la contra-rotation tend à favoriser leur apparition. Ces résultats numériques, concluants, confirment des résultats expérimentaux récents, recensés dans la littérature. De même, les solutions indiquent qu’une légère inclinaison de la paroi latérale constitue un nouveau moyen, non-intrusif, de contrôle
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    Vortex breakdown control in confined swirling flows
    (2008) Saci, Rachid; Kouadri, Amar
    Confined steady flows, which display on-axis or off-axis vortex breakdown, have been numerically studied, with particular attention focused on means of controlling the vortex breakdown bubbles. Firstly, the model flow driven by one end disk of a cylindrical enclosure, which exhibits two distinct on-axis vortex bubbles, has been considered. The resulting computations revealed that, sloping slightly the stationary sidewall, beyond a threshold angle, provided an effective means of removing the secondary vortex structure, and the flow remains steady. Besides, this technique is shown to significantly modify the flow topology which displays off-axis bubbles, induced by the co-rotation of the end disks. Then, the effectiveness of adding a near-axis swirl, as suggested in recent experimental works, has been analysed numerically and found to substantially alter on-axis reverse flows