Heat transfer enhancement of Fe ₃ O ₄ ‐water nanofluid by the thermo‐magnetic convection and thermophorestic effect

The promotion of the heat transfer by ferro-nanofluid under a magnetic field has caught more extensive attention in the field of nuclear industry and energy engineering. Firstly, a modified model based on the Buongiorno model was proposed to investigate the heat transfer considering the Kelvin force in the presence of an inhomogeneous magnetic field to elevate the heat transfer performance of nanofluid using thermomagnetic convection. Secondly, the influence of Kelvin force, thermophoresis, and Brownian motion of nanoparticles on the heat transfer at a moderate Reynolds number was investigated. The numerical results indicate that the chaotic convection induced by the Kelvin force and the thermophoretic effect are much important factors. Thirdly, the numerical results demonstrate that the NSN and NSN/SNS arrangements of magnets should be the preferential selection. Besides, the more powerful magnetic field and greater volume fraction of nanoparticle can produce better heat transfer performance. Finally, the discussions on the underneath mechanisms for heat transfer augment are conducted, and it can be concluded the thermomagnetic convection induced the combination of the magnetic effect and thermophoretic effect may be the key mechanism.