A LATTICE BOLTZMANN STUDY OF NANO-MAGNETO-HYDRODYNAMIC FLOW WITH HEAT TRANSFER AND ENTROPY GENERATION OVER A POROUS BACKWARD FACING-STEP CHANNEL

Abstract

In this study, a numerical investigation of a magneto-hydrodynamic (MHD) and backward-facing nanofluidic flow was performed using the thermal lattice Boltzmann method (LBM) with multiple distribution functions to handle dynamic and thermal fields, including the magnetic force. The Cu-H₂O based nanofluid is considered as the working fluid, and the Brinkman-Forchheimer model is adopted to mathematically formulate the porous medium. In addition, heat transfer, pumping power, thermal performance index, and entropy generation within a backward-facing step open-ended channel with adiabatic walls has been investigated. A preliminary comparison of the simulation outcome with available numerical results shows that the in-house built code aptly describes the nanofluid flow behavior and heat transfer process. Afterward, a parametric examination of the impact of Hartmann number (0.0 &le; <i>Ha</i> &le; 25), Darcy number (10^-3 &le; <i>Da</i> &le; 1.0), Eckert number (0 &le; <i>Ec</i> &le; 10), nanoparticles volume fraction (0&#37; &le; &phi; &le; 4&#37;), and magnetic field tilt (0 &le; &gamma; &le; &pi;/2) on streamlines, isotherms, friction factor (<i>C_f</i>), pressure drop, pumping power, average Nusselt number (<i>Nu</i>_av), thermal performance index (<i>PI</i>), and average entropy generation ratio (S*) has been conducted. Based on the findings obtained, it can be stated that increases in the nanoparticles' volume fraction and <i>Ha</i> rise <i>Nu</i>_av, pressure drop (&Delta;<i>P</i>), and pumping power (<i>P_pump</i>) occur. On the other hand, <i>PI</i> and S* drop when &phi; and <i>Ha</i> rise. Bejan's number has also been shown to increase with <i>Ha</i>. It also turned out that increasing the magnetic field tilt involves a rise in heat transfer, pressure drop, and pumping power, except for <i>PI</i> and entropy generation.