Natural Convection and Entropy Generation in a Porous Enclosure Filled with Non-Newtonian Nanofluid

In the present work, the analysis of natural convection and entropy generation in a square porous cavity, having either a flat or a wavy vertical wall, filled with a non-Newtonian nanofluid is reported. The effect of Rayleigh number , non-Newtonian power-law index (0.6–1.4), Darcy number (0.0001–0.01), Hartmann number (0–90), and volume fraction of CuO nanoparticles (0–0.12) on heat transfer characteristics has been thoroughly examined. It is found that the average surface Nusselt number for an undulated wall is less than that of a plane wall. for all the cases increases with and and decreases with . The mixing of the nanoparticles with both Newtonian and non-Newtonian fluids enhances the heat transfer only for of 0.01 and less than 30 for all . When is low at 0.0001, the addition of nanoparticles to a fluid enhances the heat transfer for all the cases except of at less than 1. The entropy generation is significant near the vertical wall because of the higher temperature and velocity gradient. The magnitude of is found to be very less as compared with and . , , and increase with an increase in for all cases; however, for a of 60 or 90, there exists an optimum for for a ranging from 0.0005 to 0.001. Finally, the correlation for the average surface as a function of the pertinent input parameters has been proposed for both Newtonian and non-Newtonian fluids, which can be referred in the academics and the industrial world.