EMHD Flow of Ternary Nanofluids Over Stretching/Shrinking Surfaces With Velocity Slip in Porous Media: A Carreau Model for Multiple Geometries

This study presents a comprehensive numerical investigation of electromagnetohydrodynamic (EMHD) boundary-layer flow and heat transfer of a ternary hybrid nanofluid comprising Fe3O4, carbon nanotubes (CNTs), and graphene oxide (GO) dispersed in engine oil. The flow over stretching and shrinking surfaces embedded in a Darcy–Forchheimer porous medium is analyzed considering Carreau-type shear-thinning behavior across flat plate, wedge, and stagnation-point geometries. The governing nonlinear partial differential equations are reduced via Lie symmetry transformations and solved numerically using the RKF45 shooting method in MAPLE. The novelty of this work lies in the integrated analysis of ternary nanoparticles, EMHD effects, surface slip, and radiative heating within a unified framework. Results show that ternary hybridization significantly enhances thermal performance, achieving up to a 5.51% increase in heat transfer compared with mono- and binary nanofluids, with Nusselt number rising from 0.0983 to 0.1005 when the nanoparticle volume fraction increases from 0.01 to 0.02. Key parameters such as wedge angle (γ), nanoparticle volume fraction (ϕ), Weissenberg number (Wi), magnetic field strength, porous medium permeability, stretching/shrinking rate, and slip conditions are: found to strongly influence velocity and temperature profiles. Overall, the study provides a robust theoretical framework for optimizing high-performance nanofluid-based thermal systems, with potential applications in microscale heat transfer devices, electronic cooling, and automotive energy systems.