Effect of base fluid on mixed convection nanofluid flow over microscale backward-facing step

The numerical implementation of laminar mixed convective flow over a 3-D horizontal microscale backward-facing step (MBFS) is presented to explore the effect of base fluid on the flow and heat transfer characteristics. The energy equations and momentum were discretized by means of a finite volume method (FVM). The SIMPLE algorithm used for the pressure correction and velocity fields in the entire domain in the procedure. The straight wall of the duct was at a constant temperature (Tw = 323 K). While the downstream wall maintained at uniform heat flux (Qw = 12 Watt). The SiO2 nanoparticles with diameter of 25 nm and volume fraction of 0.04 were immersed in four kinds of base fluids (glycerin, engine oil, ethylene glycol and water). The Reynolds number is maintained at Re = 35, and step height was 650 μm. The results revealed that the highest Nusselt number was with using glycerin as a base fluid. It is also revealed that the skin friction coefficient was higher with using water as a base fluid.