Study of magnetohydrodynamics-based-mixed convection & entropy generation within the rectangular enclosure with two obstacles for Cu-SiO₂ multiwalled carbon nanotubes ternary hybrid nanofluids

Abstract

This work employs the multirelaxation time lattice Boltzmann method (MRT-LBM) to investigate the heat transfer and entropy generation characteristics due to mixed convection in a rectangular enclosure with a discrete heater subjected to an external magnetic field. The enclosure contains Cu-SiO₂ multiwalled Carbon nanotubes ternary nanofluid. In particular, the effect of Hartmann number (0 ≤ Ha ≤ 90), Richardson number (0≤ Ri ≤ 10), the volume fraction of nanofluids (0 ≤ $\varphi$≤1), and the location of obstacles over the various aspects of thermohydrodynamics and entropy generation characteristics have been elaborated. Three cases are categorized based on the arrangement of the obstacles in the enclosure. Case 1 and Case 3 represent the alienated arrangement of the obstacles where the first obstacle is located below and above the second, respectively, while Case 2 represents the in-tandem arrangement of the obstacles. The results illustrate the reversal of flow velocity at Ha = 90 for all Ri. It is observed that case 2 is best suited for Nusselt number enhancement. It is seen that when Ri = 0.1 and 1 Case 2 and at Ri = 10, Case 1 augments heat transfer for Ha = 0.

Keywords:

• Adiabatic obstacle
• mixed convection
• MRT-LBM
• ternary hybrid nanofluid

Annex