Hydro-magneto-thermal performance and irreversibility analysis of copper and aluminum oxide-based nanomaterial inside an octagonal enclosure

This study aims to explore the influence of the magnetic field on the buoyancy-driven flow behavior of a hybrid nanomaterial within an impermeable, rigid octagonal enclosure, which consists of a heated circular cylinder. The rectangular fins of variable lengths are attached to the circular cylinder. The considered nanomaterial within an octagonal enclosure is copper and aluminum nanoparticles suspended in water (Cu–Al 2 O 3 /H 2 O). Further, boundary configurations are that the horizontal (lower and upper) walls of an octagonal cavity are kept at high temperature, the vertical walls remain at low temperature and the remaining inclined walls are insulated. Numerical simulations are carried out on the nondimensional governing equations by implementing the Finite Element Method (FEM) incorporating the Galerkin algorithm in robust COMSOL-MULTIPHYSICS software. The velocity field, entropy generation, temperature, Nusselt number, and Bejan number are simulated via streamlines and isotherms. The impact of significant parameters like Hartmann number ([Formula: see text]), heat generation parameter ([Formula: see text]), Rayleigh number ([Formula: see text]), and size of the fins ([Formula: see text], 0.12, 0.17) are also analyzed. The current findings are directly relevant to thermal management systems, viz., compact heat exchangers, electronic device cooling, and solar thermal collectors, where minimal irreversibility and efficient heat dissipation are crucial, as the heat dissipation and irreversibility are explored in the study. Model validation confirms the reliability of the numerical approach. It is found from the study that the temperature within an enclosure is enhanced with a rise in the size (H) of the fins. Entropy reduces with an increase in Hartmann number Ha and size of fins which is a favorable case for a thermal storage system. The average Nusselt number is a decreasing function of Ha and Q and an increasing function of Ra.