In this paper, CFD modeling of turbulent heat transfer behavior of Magnesium Oxide–water nanofluid in a circular pipe was studied. The base fluid was pure water and the volume fraction of nanoparticles in the base fluid was 0.0625%, 0.125%, 0.25%, 0.5% and 1%. The applied Reynolds number range was 3000- 19000.Three individual models consist of single phase, VOF and mixture were used. The results showed that the simulated data were in good agreement with the experimental ones. According to the experimental work (literature) and simulation (this research), heat transfer coefficient (h) and Nusselt number (Nu) increased with increasing volume fraction of nanofluid. These data were more than those of pure water. It was concluded that two phase models are more accurate than the others for prediction of upper volume fraction of nanoparticle.
