A numerical investigation is carried out to assess the hydrothermal performance of a water-based hybrid nanofluid
containing both Fe3O4 (magnetite) nanoparticles and carbon nanotubes (CNTs) in a heated tube in the presence of a
constant non-uniform magnetic field. The magnetic field is created by three pairs of permanent magnets. The effects of
Reynolds number, magnetite, and CNT volume concentrations as well as magnetic field strength are investigated. The
acquired data for the case of without magnetic field confirmed higher values of heat transfer and pressure drop as a result of
utilizing nanofluid compared with water. Additionally, it was found that the Nusselt number and pressure drop of the
studied nanofluid samples increase significantly under the magnetic field. Moreover, the influence of magnetic field
increases with an increase in the nanoparticle concentrations and magnetic field strength and decrease in the Reynolds
number. The maximum increments of 109.31% and 25.02% in comparison with the case of without field were obtained in
the average Nusselt number and pressure drop for hybrid nanofluid containing 0.9% magnetite and 1.35% CNT at Reynolds
number of 500.