| Abstrakt: |
The Graetz-Nusselt problem is addressed with non-Newtonian power-law nano fluids with slip boundary conditions. In the said fluid model, the power-law coeffcient m and ow index n depend on the nanoparticle concentration φ. The Al2O3-water nano fluid is considered and results are obtained for typical values of nanoparticle concentration, i.e., φ = 1%,2%,3%,4% and 5%. First of all, we calculate the analytical solution of the fully developed velocity field for power-law nano fluid via the Navier linear slip law. Next, the temperature profile is obtained by utilizing the condition of the specified surface temperature. The longitudinal conduction (which is possible with a low Peclet number) is also considered. The graphical results of mean temperature and local Nusselt number are presented for various values of slip length, nanoparticle concentration, power-law index, and Peclet number. As expected, the concentration of nanoparticles boosts the heat transfer rate, while the slippery boundaries always provide larger ow rates of nano fluid. The analysis reveals that the presence of nanoparticles increases the local Nusselt number and mean temperature. Furthermore, the thermal entry length is considerably enhanced upon raising the nanoparticle concentration and slip length. In addition, decreasing the Péclet number also enhances thermal entrance length. [ABSTRACT FROM AUTHOR] |
