Numerical study of magnetic field effects on the mixed convection of a magnetic nanofluid in a curved tube

•We modeled hydrothermal behavior of a ferrofluid in a curved tube using mixture model.•Non-uniform magnetic fields were implemented in the perpendicular direction of the flow.•The heat transfer is enhanced due to the secondary flow augmentation.•Secondary flow due to magnetic field is enhanced using high magnetic field gradients.

In this paper, effects of applying a linear magnetic field on a ferrofluid (water and 4 vol% Fe3O4) flow in horizontal straight and curved tubes have been investigated. The hydro-thermal behavior of the flow is investigated numerically using the two phase mixture model and control volume technique. The linear magnetic fields with various gradients in the perpendicular direction of the main flow have been examined. Based on the obtained results the heat transfer coefficient can be enhanced using the curved tube instead of straight tube, adding magnetic nanoparticles to the base fluid and applying external magnetic field. It is concluded that the heat transfer is enhanced due to the secondary flow augmentation (because of centrifugal force and Kelvin force) and thermal conductivity improvement (because of high thermal conductivity of magnetic nanoparticles relative to base fluid).