Effect of Cavity Undulations and Thermal Boundary Conditions on Natural Convection and Entropy Generation in CuO-Water/Al2O3-Water Nanofluid

Abstract

The present work reports natural convection and entropy generation inside the cavity (with a plane or undulated wall) filled with CuO-Water or Al2O3-Water nanofluid. The results are produced considering the effect of Rayleigh number, Darcy number, Hartmann number and volume fraction of nanofluid (Φ). Heat transfer improves with the mixing of nanoparticles only for the case of Da of 0.01 for all Ra. Various thermal boundary conditions such as uniform, sinusoidally and linearly varying temperature have been imposed at the wavy hot wall. It is found that the average surface Nu for the cavity with uniform temperature is more compared to sinusoidally or linearly varying temperature. Nu for a cavity filled with Al2O3-Water nanofluid is slightly lower than the CuOWater nanofluid for all cases. Local Nu for the plane and undulated wall has been plotted, which shows that it is maximum at the crest of the undulated wall. In addition to the heat transfer, entropy generation is determined against all the relevant parameters, which adds more value to the present work.