Numerical Analysis of Unsteady Natural Convection in a Circular Enclosure With an Internal Hot Channel: Combined Impact of Exothermic Reaction and Magnetohydrodynamics on Aluminum Oxide/Water

ABSTRACT Overheating, decreased performance, and system failures can result from ineffective thermal management in electronics, energy systems, and industrial processes where high‐efficiency heat exchange is essential. This study delves into the sophisticated heat transfer characteristics and flow dynamics of an aluminum oxide‐water nanofluid filled in a circular configuration containing a chamfered square heater at its center. Optimizing the efficiency of heat transfer requires an understanding of how nanofluids behave in these geometries. The study employs numerical simulations to comprehend different factors' impact on fluid dynamics and heat exchange process. The operating parameters, such as Rayleigh number (10 3 , Frank–Kamenetskii factor (, Hartman number , heater diameter to enclosure diameter ratio (, and concentration of nanosolids (), were methodically investigated. The methodology includes solving the governing equations for mass, momentum, and energy conservation utilizing the finite element technique. In contrast to earlier research on straightforward heaters, this study examines a chamfered square heater and shows how its shape affects flow and heat transfer in response to magnetic fields and nanoparticle loading. The investigation outcomes reveal that raising the Rayleigh number to 10 5 causes convection enhancement, increasing fluid speed by more than 5.81% and heat transfer efficiency and significantly raising the average Nusselt number by 187.5%. While increasing the Frank–Kamenetskii factor to F k = 4 has no effect on flow dynamics, it may decrease the average Nusselt number by 63%, which would lessen the efficiency of heat transmission. Furthermore, changing the chamfered square heater's diameter impacts heat transmission and fluid motion, with smaller diameters encouraging greater heat exchange and higher fluid velocities. Aluminum oxide nanoparticles remove vortices and improve thermal conductivity to improve fluid motion and heat transmission; nevertheless, fluid velocity is hindered by overly high concentrations of the nanoparticles. Reducing the Hartman number highlights the impact of magnetic field intensity on nanofluid behavior by increasing fluid velocity and heat transfer by achieving a rise in Nu avg of 22.4%. By clarifying the complex relationships between operating parameters and nanofluid behavior in enclosed geometries, these findings aid in the optimization of thermal management systems.