Significance of porous elliptical cylinder on the MHD natural convection

Abstract

In this analysis, the significance of different alignments of porous elliptical cylinder and orientation of magnetic field intensity on the buoyancy driven flow and heat transfer traits in an enclosure is investigated through lattice Boltzmann technique. Various amalgamations of the orientations of curved porous cylinder and magnetic field are carried out for the first time, which is essential in real-time applications like compact electronic devices, nuclear reactor cooling, and heat exchangers. The classical outcome of the individual parameters considered in the study can be altered through different combinations, and this information serves for the favourable heat transfer performance. This parametric study focuses on the effects of buoyancy force (Ra=104, 105, &106), non-dimensional permeability (Da=10−5, 10−4, &10−3), magnetic field intensity (Ha=0, 25, & 50), magnetic field orientation (γM=0°, 45°, &90°), and orientation of the porous elliptical cylinder (Case-1=0°, Case-2=30°, Case-3=45°, &Case-4=90°) on the hydro-thermal behaviour in and around the porous cylinder. The Darcy–Brinkman–Forchheimer equation is linked with the LB flow evolution equation to obtain the flow features of porous medium. It is observed that the flow-field intensity in and around the porous zone is directly proportional the imposed buoyancy force and permeability. Unsteady traits in flow and thermal fields are seen at higher Ra and Da when the porous body is not streamlined. The amount of fluid penetration and the distance travelled by it in the porous zone are the deciding factors for the heat transfer variation of different orientations of the porous cylinder. The sway of buoyancy force on the heat transfer intensification is hampered by the intensity of magnetic field. In the case of Θ=0° the % increment in mean Nusselt number (NuM) at Ra=105 with respect to Ra=104 is 108.2%, 66.6%, & 18.2% for Ha=0, 25, & 50, respectively. Although, magnetic field has displayed adverse influence on the thermal performance, by tuning the orientation of the magnetic force, the heat transfer can be significantly improved (about 9.3% increment when γM=90°, Ra=106&Da=10−3). The impact of magnetic field and its orientation are found to be significant when the buoyancy force and permeability are more. At lower permeabilities of the cylinder, the streamlined shape offered higher heat transfer rate, whereas, at higher permeabilities such pattern reverses. Besides, it is seen that few amalgamations of parameters embraced in the study offered a drastic variation in flow and heat transfer behaviour.