Oblique stagnation point flow of hybrid nanofluid on a stretching sheet with modified thermal conductivity models and Darcy's law

Abstract

Hybrid nanofluids have demonstrated improved thermal performance and stability across a wide range of applications, including thermal efficiency systems, solar collectors, energy production, nuclear processes, and enhanced heat transfer. Motivated by these promising applications, this study investigates two-dimensional incompressible oblique stagnation point flow over a stretching/shrinking sheet embedded in a porous medium. The analysis compares two widely used thermal conductivity models, the Yamada-Ota and Xue models, for hybrid nanofluids composed of graphene oxide ($GO$) and iron oxide, magnetite ($F{e}_3{O}_4$) nanoparticles dispersed in a non-Newtonian engine oil (EO) base fluid. Additionally, the influences of thermal radiation, heat generation/absorption, and chemical reactions are incorporated to explore the heat and mass transfer characteristics. The governing equations are transformed into a system of ordinary differential equations using similarity transformations, and the resulting system is solved numerically via the fourth-order Runge-Kutta-Fehlberg integration method combined with an efficient shooting technique. The results reveal that increasing the magnetic field strength enhances the fluid temperature while reducing its velocity. Higher heat generation parameters lead to intensified thermal distribution, while lower permeability increases velocity instability. Quantitatively, the Xue model demonstrates a higher surface heat transfer rate than the Yamada-Ota model, and a larger Schmidt number reduces mass transfer rates. These insights are particularly valuable for optimizing heat and mass transfer in porous thermal management systems.