Combined convection nanofluid flow and heat transfer over microscale forward-facing step

The laminar mixed convection flow of nanofluids over a 3D horizontal microscale forward-facing step (MFFS) was numerically investigated using a finite volume method. Various nanoparticle materials, such as SiO₂, Al₂O₃, CuO, and ZnO, were dispersed in ethylene glycol as a base fluid with volume fractions in the range of 0 and 0.04. The duct has a step height of 650 ìm. The downstream wall was heated with a uniform heat flux of 12 Watt, and the straight wall of the duct was kept at a constant temperature of 323 K. The Reynolds number value was maintained at 35. The results revealed that the SiO₂ nanofluid had the highest Nusselt number, which increased with decreasing nanoparticle material density, increasing volume fraction and decreasing nanoparticles diameter. The static pressure and the wall shear stress increased with increasing particle volume fraction and decreasing particle diameter. Moreover, the nanoparticle volume faction, material and diameters had small effect on the skin friction coefficient.