Falkner–Skan quaternary hybrid nanofluid dynamics and thermal transport with thermal radiation and aligned magnetic field

Despite growing interest in quaternary hybrid nanofluids (QHNFs) containing four distinct nanoparticles, the combined effects of magnetic field orientation and thermal radiation on Falkner–Skan wedge flow remain insufficiently understood. This study investigates the hydrodynamic and thermal behaviour of Al₂O₃–Cu–TiO₂–Ag/water QHNF over a wedge, focusing on the coupled influences of magnetic field orientation, pressure gradient, and thermal radiation. Similarity transformations reduce the governing equations to a system of ordinary differential equations, which is solved numerically using the Keller–Box method. Increasing the magnetic-field inclination angle from 0° to 90° increases the skin-friction coefficient and local Nusselt number by approximately 109.4% and 18.5%, respectively, for the wedge, compared with 149.2% and 25.0% for the flat plate. QHNF exhibits the highest heat-transfer performance among the NF, HNF, THNF, and QHNF formulations for both wedge and flat-plate configurations, whereas the skin-friction response is non-monotonic. The favourable pressure gradient associated with the wedge geometry and magnetic-field inclination modify the effects of thermal radiation on transport characteristics. These findings highlight geometry-dependent electromagnetic and radiative transport mechanisms relevant to high-temperature thermal management and provide useful insights for designing advanced nanoparticle-based heat-transfer systems.