Effect of shape of nanoparticles on mixed convection nanofluid flow in a porous medium with variable permeability: Analysis of the second law of thermodynamics

Second law analysis of copper-water nanofluid flow in an inclined channel filled with a porous medium having variable permeability is presented in the literature. Hydrodynamic slip and convective boundary conditions are assumed for the flow. Nanoparticles of different shapes are considered, namely, platelet, blade, cylinder and brick. The permeability of the porous medium is assumed to decrease exponentially across the width of the channel. The highly non-linear governing equations are solved using the homotopy analysis method and verified with a closed form solution for a reduced equation. Moreover, comparisons with the existing literature are presented, the results of which were found to be in excellent agreement. Impact of pertinent flow parameters influencing the flow on entropy generation, Bejan number, Nusselt number, skin friction and volume flow rate are discussed and supplemented with graphs. Platelet-shaped nanoparticles have generated the least amount of entropy in the study. The impact of channel inclination angle on skin friction was observed to be highly significant in the analysis.