Numerical investigation on natural convection of nanofluids in an inclined square enclosure with non-uniform heated walls

Abstract

Studying natural convection of nano uids in enclosures with non-uniform heated walls is of importance in many engineering applications such as solar energy collection. In this study, we developed a Fully Higher-Order Compact (FHOC) nite di erence method to investigate the natural convection and heat transfer of nano uids in an inclined square enclosure with sinusoidal temperature distributions. Numerical simulations were performed over a range of amplitude ratios, inclination angles, phase deviations, nanoparticles volume fractions, and Rayleigh numbers. Results showed that heat transfer could increase signi cantly by increasing the amplitude ratio and inclination angles in nano uids. Moreover, elevating the nanoparticles volume fraction did not always enhance the heat transfer of nano uids. When the Rayleigh number Ra was low (Ra = 10 3 ), the average Nusselt number decreased as the solid volume fraction parameter, , increased. On the other hand, elevating had favorable e ects on the heat transfer of nano uids when Ra was high (e.g., Ra = 10 4 , 10 5 ). With Ra = 10 4 , the total heat transfer rate decreased with nanoparticles in the order of Cu, CuO, Al2O3, and TiO2. Finally, a correlated expression of the total average Nusselt number, the Rayleigh number, and the solid volume fraction of nanoparticles was empirically obtained.

Thermophoresis and Brownian motion effects of nanoparticles on Radiative heat transfer in Hiemenz flow: Using Spectral Method

“…Hakeem et al [38] numerically investigated the second law for MHD nano uid ow over the stretching surface and showed that nanoparticles generated more entropy than non-metallic particles. Wang and Dai [39] considered natural convection of nano uid in an inclined square cavity with non-uniformly heated walls and found that at a xed Rayleigh number, average Nusselt number was higher for copper nanoparticles. Kasmani et al [40] reported the e ects of thermal radiation, Soret, and Dufour on convective heat transfer of nanoliquid over a wedge in the presence of wall suction and proved that temperature distribution enhanced by raising the values of wedge angle, radiation, Brownian motion, and thermophoresis parameters.…”