Axial Magnetic Field Effect on Taylor-Couette Flow

This study is interested in the effect of an axial magnetic field imposed on incompressible flow of electrically conductive fluid between two horizontal coaxial cylinders. The imposed magnetic field is assumed uniform and constant. The effect of heat generation due to viscous dissipation is also taken into account. The inner and outer cylinders are maintained at different uniform temperatures. The movement of the fluid is due to rotation of the cylinder with a constant speed. An exact solution of the equations governing the flow was obtained in the form of Bessel functions. A finite difference implicit scheme was used in the numerical solution. The velocity and temperature distributions were obtained with and without the magnetic field. The results show that for different values of the Hartmann number, the velocity between the two cylinders decreases as the Hartmann number increases. Also, it is found that by increasing the Hartmann number, the average Nusselt number decreases. On the other hand, the Hartmann number does not affect the temperature

Etude analytique et numérique du transfert de chaleur et de masse dans un écoulement de type TCP

Ce travail s’intéresse à l’étude analytique et  numérique de l’influence  du nombre de Reynolds sur le transfert de chaleur et de matière dans un espace annulaire entre deux cylindres coaxiaux, le cylindre intérieur est mis en rotation, sa paroi est maintenue à une température fixe. Le problème est résolu numériquement par la méthode  de différences finies. On étudie le cas de faibles valeurs de Schmidt correspondant aux cas des gaz. Le nombre de Reynolds varie entre 100 et 600

Étude dynamique et thermique de l'influence d'un champ magnétique axial sur un écoulement entre deux cylindres horizontaux en rotation

Cette étude s’intéresse à l’effet d’un champ magnétique axial imposé sur un écoulement incompressible d’un fluide électriquement conducteur entre deux cylindres coaxiaux horizontaux en rotation Le champ magnétique imposé est supposé uniforme et constant, aussi on considère la génération de la chaleur due à la dissipation visqueuse. Les parois du cylindre intérieur et extérieur sont maintenues à des températures différentes et constantes. Le mouvement du fluide est dû à la rotation de cylindre intérieur avec une vitesse constante. Une solution exacte des équations régissant l’écoulement a été obtenu sous forme de fonctions de Bessel. Un schéma implicite de différences finies a été utilisé pour la résolution numérique. Les distributions de vitesse et de températures ont été obtenues avec l’influence du champ magnétique aussi bien que sans le champ magnétique. Les résultats montrent que pour des valeurs modérées du nombre de Hartmann, la vitesse azimutale entre les deux cylindres s’aplatit d’avantage au fur et à mesure que le nombre de Hartmann Ha augmente, aussi en augmentant le nombre de Hartmann, on constate une nette diminution du nombre de Nusselt

Etude numérique du transfert de masse d'un écoulement de Taylor-Couette-Poiseuille

The influence of the radius ratio N and the number of Schmidt on the mass transfer is numerically investigated in the gap between two concentric cylinders with an imposed axial flow. The annular space varies from 0.3 to 0.75. The Reynolds and Schmidt number vary respectively from 100 to 2500 and from 0.7 to 1000. Two cases are considered; inner or outer cylinder is activated. The results show that hydrodynamic instabilities appear for values of Sc Re= 10+4. The radial concentration profile shows the existence of an important gradient at the activated wall that it varies with the axial position. The variation of the mass transfer coefficient K for different Schmidt number and a fixed radius ratio show the increase of the mass transfer with the Schmidt number. The reduction of the annular space promotes mass transfer. The radial concentration gradient is more important for gases (small values of Schmidt) then for liquids (large values of Schmidt). The mass transfer is more important at the inner cylinder. The Sherwood number is proportional to Re+0..3

Women's Experiences of Breastfeeding in a Bottle-Feeding Culture

We consider an ascending laminar air flow in a vertical channel formed by two parallel flat plates wetted by a thin water film and under different temperature and concentration conditions. The study includes a numerical finite volume method for the treatment of the double diffusion problem, where the analytical solution is given to the thermal diffusion. The analytical study showed that the reversed flow is observed only under some wall temperature conditions and also for certain values of Re/Gr. The reversed flow is also strongly dependent on the aspect ratio A, which is based on the cross section of the channel. Indeed, the results show than this dependence is very strong for values less than a certain critical one equal to 2.22. In the absence of the mass transfer the results showed that the evaporation rate remains null along the channel, decreases when the mass gradient is favorable and it finally vanishes at x=15. However, the evaporation rate increases in the case of an unfavorable mass gradient, to cancel at position x=20, then merges with the curve representing the forced convection. In the absence of heat transfer the evaporation rate is less important and amounts to fifty percent of the double diffusion. The results obtained by the analytical and numerical methods are compared each other and with those of a similar works and a good agreement was found