This study aims at experimentally investigating the influence of magnetic field on the rheological behavior of water–carbon nanotube (CNT)/magnetite (Fe3O4) nanofluid. Tetramethylammonium hydroxide (TMAH) and Gum arabic (GA) are respectively used to stabilize the nanofluid. Scanning Electron Microscope (SEM), Dynamic Light Scattering (DLS) and X-ray Diffraction (XRD) methods were used to characterize the prepared nanofluid samples. Experiments were performed to evaluate the viscosity of water– CNT/magnetite nanofluid in the shear rate range of 1–100 s−1, volume fraction range of 0.5-1.5%, and magnetic field strength range of 0–480 mT. It was found that the presence of an external magnetic field causes an increase in the viscosity of the water– CNT/magnetite nanofluid. In addition, the results depicted that the viscosity of the nanofluid augments by boosting the concentration of the nano-materials. Moreover, it was reported that increasing the magnetic field strength to more than 360 mT has a negligible influence on the augmentation of nanofluid viscosity. Furthermore, the non- Newtonian shear thinning behavior was depicted because of the decrease in viscosity with intensifying the shear rates.
