A Numerical study on Turbulent flow and heat transfer of water-Copper Nan fluid Over Unequal Obstacles located at the Ieading edge of a Surface

Turbulent flow and heat transfer of water-copper nanofluid at the leading edge of a surface with two unequal obstacles issimulated numerically. The importance of this study is to simultaneously consider the effect of flow obstacles and nanoparticles on flow and heat transfer of turbulent boundary layer, which can not be found in previous literatures. Turbulent modeling is performed by a modified k- model with two-layer zonal Wolfstein model for near wall treatment. The effects of Reynolds number, distance between the obstacles, the volume fraction and diameter of nanoparticles on the flow parameters are investigated. The results indicates that by changing both the blocks distance and solid volume fraction, the size of recirculation zone between the blocks changes and consequently, the Nusselt number is affected. At large distance between the obstacles, the recirculation zone behind the first block can not reach the second block and hence, the rate of heat transfer decreases. At low Reynolds numbers, convective heat transfer is less than thermal diffusion and therefore, the heat transfer rate is less influenced by the solid volume fraction. Moreover, due to the role of nanoparticles motion on the rate of convective heat transfer, smaller nanoparticles in diameter are more effective in heat transfer enhancement.