Impact of Hartmann number and aspect ratio on the heat and mass transfer characteristics in a hexagonal enclosure with a heated circular obstacle inside

Abstract

Hyrdo-thermal performance study in enclosures or cavities is a very promising field of study for industrial components design and implementation. Previous studies have investigated various shapes and conditions, but there is a significant research gap in studying the fluid flow and thermal performance of hexagonal enclosures with circular obstacles under natural convection regimes with the application of magnetic fields. Thus, this study plans to inspect the fluid behavior and thermal performance in a hexagonal-shaped enclosure with a heated bottom wall and circular obstacle using Casson fluid. The variables chosen for analysis include the Hartmann number (0 ≤ Ha ≤ 100), aspect ratio (0.10 ≤ AR ≤ 0.20), Casson number (1 ≤ β ≤ 10), Lewis number (1 ≤ Le ≤ 10), buoyancy ratio (1 ≤ N ≤ 10), and inclination angle of the magnetic field (0° ≤ γ ≤ 90°). The findings are plotted as streamlines, isotherms, iso-concentration plots, and variable plots of average Nusselt and Sherwood numbers for various Casson numbers, buoyancy ratios, Lewis numbers, and inclination angles for variable Hartmann numbers. Results show that both aspect ratio and Hartmann number increase the thermal performance and mass transfer in the enclosure. Buoyancy ratio and inclination angle have a significant role in increasing heat transfer rate. On the other hand, higher Casson number, Lewis number, and buoyancy ratio ensure better mass transfer in the study.