Forced convection heat transfer in a channel under the influence of various non-uniform transverse magnetic field arrangements. (November 2016)

• Record Type: Journal Article
• Authors: Larimi, M.M.; Ghanaat, A.; Ramiar, A.; Ranjbar, A.A.
• Is Part Of: International journal of mechanical sciences. Volume 118(2016)
• Page Start: 101
• Page End: 112
• Publication Date: 2016-11
• Subjects: Ferro-fluid -- Non-uniform magnetic field -- Heat transfer -- Surface friction; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2016.09.023
• Languages: English
• ISSNs: 0020-7403

Abstract

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 Fe3 O4 ) 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. Highlights: The effect of non-uniform transverse magnetic field on heat transfer augmentation along the channel is investigated. Rising magnetic number show a significant effect on local Nusselt number due to increasing recirculation in ribs area. It is investigated that the effect of magnetic source on Nusselt number would be more sensible if the all current carrying wires are in one side of channel. The results showed that magnetic field could increase pressure drop and surface friction coefficient along the channel, especially at low Reynolds number.