Synergistic Heat Transfer Enhancement in Triangular Enclosures: Hybrid Nanofluid‐Porous Wavy Fin Systems Under Magnetohydrodynamic and Radiation Effects

ABSTRACT This study numerically investigates thermal transport and fluid dynamics in a triangular cavity filled with a MgO–Ag–H 2 O hybrid nanofluid containing an undulating porous fin under electromagnetic field and thermal radiation influences. The governing equations are solved numerically using the Galerkin finite element methodology with Darcy–Forchheimer formulation for porous media representation. A comprehensive parametric study examines the effects of Rayleigh number ( Ra , 10³–10⁶), Darcy number ( Da , 10⁻⁵–10⁻²), Hartmann number ( Ha , 0–80), magnetic field orientation angle ( γ , 0°–90°), nanoparticle concentration ( φ , 0.005–0.02), heat generation coefficient ( λ , 1–5), fin waviness parameter ( n w , 0–6), and radiation intensity factor ( Rd , 1–5). The numerical model is validated against established benchmark solutions, demonstrating excellent agreement. Findings demonstrate that increasing Ra substantially improves thermal transport and flow intensity, with the average Nusselt number rising by up to 65% and maximum velocity magnitudes increasing by over 500 times. Electromagnetic field application inhibits thermal transport, with ( Nu av ) decreasing by 55.6% as Ha increases from 0 to 80. Magnetic field angle optimization shows that γ = 60° provides better heat transfer than γ = 0° at high Ha values. Nanoparticle addition provides moderate thermal enhancement, with an 11.1% increase in Nu av as φ increases from 0.005 to 0.02, particularly in low‐ Ra regimes. Radiation effects become most significant at elevated Ra values, with ( Nu av ) nearly tripling as Rd increases from 1 to 5 at Ra = 10⁶. Entropy generation analysis reveals that the Bejan number decreases by 98.7% as Ra increases, indicating fluid friction dominance at higher Ra values. These results offer essential guidance for optimizing thermal management systems involving porous structures, nanofluids, and electromagnetic fields.