Mixed convection heat transfer and entropy generation of Cu-water nanofluid in wavy-wall lid-driven cavity in presence of inclined magnetic field

Abstract

An investigation is performed into the effects of an inclined magnetic field on the mixed convection heat transfer characteristics and entropy generation in a nanofluid-filled lid-driven cavity with a wavy surface. The heat energy transport processes within the cavity are visualized by plotting the energy flux vectors. The simulations investigate the effects of the Hartmann number, Richardson number, volume fraction of nanoparticles, inclination angle of the applied magnetic field, wave amplitude of the wavy surface, Reynolds number, and irreversibility distribution ratio on the energy flux vectors, mean Nusselt number, total entropy generation, and Bejan number. The range of the studied parameters is as follows: Richardson number from 10 − 2 to 102, Reynolds number from 1 to 300, Hartmann number from 0 to 50, inclination angle of the applied magnetic field from 0° to 360°, nanoparticle volume fraction from 0% to 4%, wavy-surface amplitude from 0.0 to 0.7, irreversibility distribution ratio from 10 − 6 to 100. It is shown that the energy flux vectors form large closed circulations under higher Richardson numbers and Reynolds numbers. In other words, the mean Nusselt number and total entropy generation increase with an increasing Richardson number and Reynolds number. By contrast, the size of the circulation structures reduces with an increasing Hartmann number. Hence, a larger Hartmann number gives rise to a lower mean Nusselt number and total energy generation. The mean Nusselt number and total entropy generation increase with an increasing volume fraction of nanoparticles and a larger amplitude of the wavy surface. In addition, for a given Richardson number, the mean Nusselt number and total entropy generation can be enhanced by tuning the inclination angle of the magnetic field. Finally, the Bejan number reduces with an increasing Hartmann number, a larger irreversibility distribution ratio, and a lower Richardson number.