MAGNETOHYDRODYNAMIC FLOW AND HEAT TRANSFER OF FERROFLUID PASSING THROUGH A CONFINED CYLINDER

Abstract

The present investigation numerically studied the hydrothermal behaviors of a ferrofluid with a mixture of water and Fe₃O₄ solid particle of 2% volume concentration over a circular cylinder settled in a confined straight channel experienced with non-uniform magnetic field throughout current transporting wires. The ferrofluid inside the confined channel is assumed as a single phase with volume fraction, Φ=2% and laminar while two symmetrical wires with respect to the channel axis are chosen as a magnetic source. The effects of Hartmann number, Ha, which denotes the magnetic field severity, Reynolds number, Re on the boundary layer detachment and normalized velocity distribution, u/U together with heat transfer enhancement factor, EF are explored utilizing Ansys Fluent 20 package program. When the magnetic field is applied non-uniformly, the flow structure turns into to steady case from an unsteady pattern for Hartmann number, Ha≥10 and separation length, L_s reduces at Re=150 due to the magnetic field induced Lorentz forces which provides extra durability to the ferrofluid flow and damps mainstream flow. According to the results of numerical simulation, the distribution and maximum value of normalized streamwise velocity component, u/U∞ attenuate as Hartmann number, Ha grows in the range of 0≤Ha≤18 since non-uniform magnetic field opposes fluid dynamics and ferrofluid flow motion. Obtained results demonstrated that the heat transfer enhancement factor, EF always improves with increase in the Hartmann number, Ha at Re=25 and 50. This increment is in the vicinity of 17% at Re=25 and 8% at Re=50 when Ha augments from Ha=6 to Ha=14.