Forced convection heat transfer in a channel under the influence of various non-uniform transverse magnetic field arrangements

Abstract

Magnetic nanofluids (MNFs) are suspensions, comprising a non-magnetic base fluid and magnetic nanoparticles. In modern set of suspensions called smart or functional fluids, fluid flow, particle movement, and heat transfer process can be controlled by magnetic fields. The present study investigated hydro-thermal characteristics of ferrofluid (water and Fe3O4) in a rib-channel exposed to several non-uniform transverse magnetic fields generated by an electric current going through several wires located perpendicularly in the flow between ribs. Two-phase mixture model and control volume technique were used to carry out the study. The effect of transverse magnetic field on heat transfer, consequent pressure loss, and wall shear stress resulting from this kind of magnetic field along the channel was investigated as well as the effect of various magnetic field arrangements. The results showed that magnetic field would have an unexpected influence on increasing Nusselt number in the channel, and raising the strength of magnetic field would cause an increase in minimum and maximum local Nusselt numbers, especially in rib regions. Furthermore, applying external magnetic field could noticeably affect fluid cooling at low Reynolds numbers. The influence of magnetic field on pressure drop and skin friction also are investigated in this study and it is illustrated that applying magnetic field increased skin friction especially in the case which whole magnetic wire located in one side on channel.