Steady flow of Jeffery–Hamel Casson hybrid nanofluid for thermal enhancement with impacts of Soret–Dufour

Improving thermal performance in modern heat exchanger systems is crucial for meeting the growing demands of energy efficiency and advanced thermal control. In this context, the present study delves into the thermophysical behavior of a steady, two-dimensional flow of Casson-based hybrid nanofluid comprising copper and graphene oxide nanoparticles within a converging/diverging channel. The model accounts for multiple interrelated physical phenomena, including the effects of viscous dissipation, internal heat generation, linear thermal radiation, Soret and Dufour mechanisms, and a magnetically influenced Darcy–Forchheimer porous medium. The core objective is to systematically analyze how these parameters influence heat and mass transfer characteristics in a confined, non-Newtonian flow domain. Through similarity transformations, the governing nonlinear partial differential equations are simplified into ordinary differential form, and the resulting boundary value problem is addressed using the Optimal Homotopy Analysis Method, known for its adaptability and precision in handling strongly nonlinear systems. Numerical interpretations reveal that an increase in approximately 4.36% in the heat transfer rate is observed within the converging channel as the radiation parameter rises highlighting the positive influence of thermal radiation on enhancing heat transfer.