This study theoretically analyses stagnation-point flow and heat transfer of a Cu and \(\text {Al}_2\text {O}_3\) hybrid nanofluid over a rotating disk, accounting for the synergistic effects of solar radiation and magnetohydrodynamic (MHD) forces. To extend beyond conventional single-particle studies, four nanoparticle geometries, sphere, column, blade, and lamina, are integrated to investigate their effects on flow dynamics, thermal conduction, and thermodynamic irreversibility. The nonlinear governing equations are first transformed into a self-similar form using an extended similarity transformation. The resulting system is then solved numerically with a cubic B-spline collocation method. The physical reliability of the solutions is verified through eigenvalue-based stability analysis. In addition, entropy generation is examined to highlight how particle shape, thermal radiation, and magnetic effects influence the overall efficiency of the system. The numerical results show that surface stretching significantly enhances heat transmission and radial velocity, with lamina-shaped nanoparticles exhibiting the best thermal performance. Temperature distributions and velocity components are significantly affected by disk rotation and magnetic field intensity, whereas increased solar radiation and Reynolds numbers decrease entropy formation, thereby increasing thermodynamic efficiency. Overall, the study offers a unified framework that emphasizes the critical role of nanoparticle morphology in optimizing radiative MHD hybrid nanofluid flows.
