Effect of Blockage Shape on Unsteady Mixed Convective Nanofluid Flow Over Backward Facing Step

Abstract

The current work studies numerically the effects of four various types of blockage shapes on unsteady-mixed convection nanofluid flow over 2D horizontal backward facing step in a duct. SiO2 is considered as nanoparticle with ethylene glycol (EG) as a base fluid, volume fraction of 2% and nanoparticle diameter of 20 nm to investigate the effect of blockage shape after analyzing the streamlines, velocity distribution, Nusselt number, and skin friction coefficient at different times. The downstream of the step was kept at temperature of 330 K, while other walls and sides of the duct were thermally insulated. The governing equations (continuity, momentum and energy) along with the boundary conditions are solved using the finite volume method (FVM). The Reynolds number was in the range of 50?Re?200. The results reveal that after ?=5 the trend of nanofluid flow and recirculation area near the step and behind the blockage shape doesn’t change sensible and this time is selected as a quasi steady time and point of comparison. The velocity distributions in the front facing triangular blockage decrease and has the most value of skin friction coefficient after Re=150.