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Stability of an Electrically Conducting Fluid Flow between Coaxial Cylinders under Magnetic field
Author(s): HAMZA BENHACINE, BRAHIM MAHFOUD, MOHAMED SALMI
Keywords: Coaxial cylinders; fluid layers; heat transfer; magnetic field; vortex breakdown.
This research aims to describe, the region of the existence of vortex breakdown, the stability margin, and the fluid layers produced by swirling flow in vertical annuli filled with an electrically conducting fluid under the combined effect of thermal gradient and the axial magnetic field. The governing Navier-Stokes, temperature, and potential equations are solved using the finite-volume method. Three combinations of aspect ratios (γ) and Reynolds numbers (Re) are compared. The pumping action sets up a secondary circulation along the meridional plane of the annular gap. For certain combinations, the vortex breakdown bubble occurred near the inner wall. Bifurcation in form of multiple fluid layers becomes apparent when the temperature difference exceeds a critical value. These fluid layers play the role of thermal insulation and limit the heat transfer between the hot top and cold bottom of the coaxial cylinders. Both the vortex breakdown and fluid layers could be suppressed by the magnetic field; the increasing of Hartmann number (Ha) would reduce the number of fluid layers. Diagrams represent the effect of increasing Richardson number (Ri) on the bifurcation (fluid layers) are established. Then stability diagrams corresponding to the transition from the multiple fluid layers zone to the one fluid layer zone for increasing Prandtl number (Pr) are obtained.

Journal of Applied Fluid Mechanics

The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating.

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