Turbulent boundary layers and hydrodynamic flow analysis of nanofluids over a plate

A numerical analysis of the log-law behavior for the turbulent boundary layer of a wall-bounded flow is performed over a flat plate immersed in three nanofluids (ZnO-water, SiO2-water, TiO2-water). Numerical simulations using CFD code are employed to investigate the boundary layer and the hydrodynamic flow. To validate the current numerical model, measurement points from published works were used, and the compared results were in good compliance. Simulations were carried out for the velocity series of 0.04, 0.4 and 4 m/s and nanoparticle concentrations 0.1% and 5%. The influence of nanoparticles' concentration on velocity, temperature profiles, wall shear stress, and turbulent intensity was investigated. The obtained results showed that the viscous sub-layer, the buffer layer, and the log-law layer along the potential-flow layer could be analyzed based on their curving quality in the regions which have just a single wall distance. It was seen that the viscous sub-layer is the biggest area in comparison with other areas. Alternatively, the section where the temperature changes considerably correspond to the thermal boundary layer's thickness goes a downward trend when the velocity decreases. The thermal boundary layer gets deep away from the leading edge. However, a rise in the volume fraction of nanoparticles indicated a minor impact on the shear stress developed in the wall. In all cases, the thickness of the boundary layer undergoes a downward trend as the velocity increases, whereas increasing the nanoparticle concentrations would enhance the thickness. More precisely, the log layer is closed with log law, and it is minimal between Y+=50 and Y+=95. The temperature for nanoparticle concentration phi=5% is higher than that for phi=0.1%, in boundary layers, for all studied nanofluids. However, it is established that the behavior is inverted from the value of Y+=1 and the temperature for phi =0.1% is more important than the case of phi =5%. For turbulence intensity peak, this peak exists at Y+=100 for v=4 m/s, Y+=10 for v=0.4 m/s and Y+=8 for v=0.04 m/s.