Entropy analysis of Hall-effect-driven TiO2−CoFe2O4/ engine oil-based hybrid nanofluid flow between spinning porous disks with thermal convective boundaries

Abstract

The applications of fluid dynamics and heat transfer between coaxial double-rotating disks are diverse and crucial across various engineering and scientific fields. This study is motivated by the growing need for efficient thermal management in advanced engineering applications, such as cooling systems, energy storage, and magnetohydrodynamic technologies. The research focuses on the heat transfer characteristics and entropy analysis of the flow of a second-grade hybrid nanofluid between two spinning porous disks, incorporating the effects of Hall currents, viscous dissipation, and thermal convective boundaries. The hybrid nanofluid consists of titanium dioxide and cobalt ferrite nanoparticles suspended in engine oil. The governing equations are transformed into non-dimensional forms using a similarity transformation and solved with the semi-analytical homotopy analysis method. Results reveal the effects of parameters on velocity, temperature profiles, Nusselt number, skin friction, entropy generation, and the Bejan number graphically. Notably, the temperature profile improves with increases in the Brinkman number and the thermal Biot number of the lower disk. In contrast, skin friction decreases with higher titanium dioxide volume fraction, porosity parameter, and magnetic field parameter. The heat transfer rate increases with a higher nanoparticle shape factor and magnetic field parameter. These findings offer significant implications for optimizing the thermal performance of nanofluids, particularly in advanced cooling systems, thermal energy storage, and magnetohydrodynamic applications where enhanced heat transfer and efficient thermal management are critical.