Numerical study of turbulent forced convection flow of nanofluids in a long horizontal duct considering variable properties

The turbulent flow of nanofluids with different volume concentrations of nanoparticles flowing through a two-dimensional duct under constant heat flux condition is analyzed numerically. The nanofluids considered are mixtures of copper oxide (CuO), alumina (Al2O3) and oxide titanium (TiO2) nanoparticles and water as the base fluid. All the thermophysical properties of nanofluids are temperature-dependent. The viscosity of nanofluids is obtained on basis of experimental data. The predicted Nusselt numbers exhibit good agreement with Gnielinskiʹs correlation. The results show that by increasing the volume concentration, the wall shear stress and heat transfer rates increase. For a constant volume concentration and Reynolds number, the effect of CuO nanoparticles to enhance the Nusselt number is better than Al2O3 and TiO2 nanoparticles.