Numerical Investigation of Magnetohydrodynamic Forced Convection and Entropy Production of Ferrofluid Around a Confined Cylinder Using Wire Magnetic Sources

The current study numerically explored the hydrothermal flow and entropy generation properties of ferrofluid (water and Fe3O4) on a cylindrical body in the rectangular channel subjected to the non-uniform magnetic field going through current carrying wires. The effect of various parameters, such as ferrofluid volume fraction, phi the strength of the non-uniform magnetic field, Ha, and Reynolds number, Re, on the flow characteristics, and forced convection heat transfer, is investigated using finite-volume-based Ansys Fluent 20. Obtained results demonstrate that the applied magnetic field shortens the length of recirculating wake downstream of the cylinder at Re = 25 and makes unsteady flow with alternate vortex shedding as time-independent steady flow for Hartmann numbers greater than Ha >= 6 at Re = 100. At Re = 50, the total drag coefficient, C-D, gets higher by almost 20% when Ha increases from Ha = 0 to Ha = 6 and subsequently grows by 61% at Ha = 10. The findings show that the average Nusselt number, Nu(avg), demonstrates monotonic behavior with the Ha and it augments when the strength of the non-uniform magnetic field increases. The Nu(avg) improvement is in the vicinity of 11.71% at Ha = 10 and 23.26% at Ha = 18 for Re = 25. The maximum value of entropy generation reduces, S-L, when the non-uniform magnetic field is applied. Moreover, increasing the Hartmann number, Ha influences the high levels region of entropy production by relatively extending this zone towards the downstream of the channel and covering more area around the cylinder. According to the outcomes of numerical simulation, there is an increase in Nu(avg) with 3.98% and 3.88% for Ha = 2 and 18, respectively, when the ferrofluid volume fraction rises from phi = 0% to phi = 4% at Re = 25. Finally, the optimum thermal performance criterion, xi, is obtained at Re = 150 for Ha = 0 and phi = 4%.