Magnetohydrodynamic nanofluids flow and heat transfer with radiative heat flux and exothermic chemical reactions

Abstract

Nanofluids are highly effective in optimizing thermal management in engineering systems. The complex and multifaceted properties of nanofluids require in-depth exploration that transcends their immediate technological and environmental applications. The exothermic chemical reactions and fundamental attributes of nanofluids have intricate mechanisms to advance flow and heat transfer. To understand the mechanisms and challenges associated with chemical reactions in nanofluids, this study investigates the flow dynamics and heat transfer in a nanofluid-filled annulus formed between a square and a circle, considering the effects of radiative heat flux, magnetohydrodynamics (MHD), and exothermic chemical reactions governed by Arrhenius kinetics. The finite element method is employed to solve the governing equations, and the accuracy of the numerical scheme is confirmed against published works. The distribution of velocity magnitude, isotherms, vorticity function, and Nusselt number are examined across a wide range of critical parameters for the copper oxide-water nanofluid. The current study also displays the heat transfer enhancement for 42 nanofluids. The results indicate that, for the copper oxide-water nanofluid, both the thermal Rayleigh number and the exothermic chemical reaction parameter significantly impact the convective flow. The average Nusselt number exhibits an increasing trend with rising Frank–Kamenetskii and Rayleigh numbers but follows a decreasing pattern with an increase in the radiation parameter. Higher Frank–Kamenetskii numbers, in conjunction with reduced radiation parameters, significantly enhance heat transfer. The Nusselt number decreases as the magnetic field intensity and the radius of the inner circle of the annulus increase. The optimal average Nusselt number is achieved with a $45°-45°-90°$ magnetic field orientation and a nanoparticle volume fraction of 3%. Copper oxide-water nanofluid shows a slightly higher average Nusselt number than the other nanofluids studied.