Thermal state interplay in inclined magnetohydrodynamics convection of ternary hybrid nanofluids with saw-tooth internal cooling

Abstract

This study presents a comprehensive numerical investigation of inclined magnetohydrodynamic (MHD) natural convection and entropy generation in a square cavity filled with a ternary hybrid nanofluid. The enclosure contains a thermally cooled saw-tooth-shaped inner structure, and the working fluid comprises Multi-Walled Carbon Nanotubes, Copper (Cu), and Ferric Oxide (Fe3O4) nanoparticles suspended in water. An external magnetic field with varying inclination angles is applied to evaluate its impact on heat and flow characteristics. The governing nonlinear partial differential equations for mass, momentum, energy, and entropy transport are solved using the Finite Volume Method, accelerated by a Full Multigrid Algorithm for computational efficiency. Key parameters including the magnetic inclination angle (χ), Hartmann number (Ha), Rayleigh number (Ra), nanoparticle volume fraction (ϕ), and four distinct thermal boundary states are systematically analyzed to understand their effects on flow behavior and thermodynamic irreversibility. The results highlight that state 3, combined with moderate Ha and χ (≈60°), offers an optimal trade-off between thermal performance and entropy generation. The study emphasizes the importance of integrating geometric design, magnetic control, and thermal boundary configuration to enhance the thermofluidic performance of MHD nanofluid systems. Future work may incorporate multi-objective optimization techniques, such as Pareto front analysis, to further refine this balance for practical engineering applications.