Modelling the Non-Isothermal Flow of a Nanofluid in a Lid-Driven Cavity from the Perspective of Irreversibility Analysis

This article examines laminar mixed convection of a nanofluid within a square cavity that contains a vertical rectangular obstacle serving as a vortex promoter. Employing Buongiorno's theory, the dimensionless governing equations are numerically solved using the finite element method to analyze the distributions of velocity, temperature, nanoparticle concentration, and entropy generation. Attention is paid to the entropy generation. Results are presented and discussed, showing that increasing the Reynolds number generates a large vortex near the obstacle, which diminishes reverse flow, enhances heat conduction, and increases entropy generation. Moreover, thermophoresis drives tiny nanoparticles from hot to cold regions, affecting heat transfer. Indeed, nanoparticle concentration decreases with higher thermophoresis (N T ) and Brownian motion (N B ) constraints, as these parameters are inversely related to the concentration profile.