Cross-diffusion effects on bidirectional mixed convection of hybrid nanofluids over a permeable wedge: A spectral approach

The present study analyzes the coupled influence of the Soret and Dufour effects on magnetohydrodynamic bidirectional mixed convection of a hybrid nanofluid flowing over a permeable wedge subjected to convective thermal boundary conditions. A mathematical formulation comprising coupled momentum, energy, and species transport equations is developed to capture the interaction between thermal and concentration gradients through the Soret (thermodiffusion) and Dufour (diffusion-thermo) mechanisms. The governing equations are transformed into a self-similar system of nonlinear ordinary differential equations through appropriate similarity variables and subsequently solved by adopting the spectral weighted residual method. The influences of the wedge parameter, magnetic field strength, mixed convection parameter, nanoparticle volume fraction, and the Soret and Dufour numbers on the velocity, temperature, and concentration fields are examined in detail. The numerical results reveal that the interaction of the Soret and Dufour effects significantly alters the coupled heat and mass transport processes by intensifying the interaction between thermal energy and species diffusion. Surface suction is found to enhance the skin friction, thereby delaying boundary-layer separation, while the hybrid nanofluid exhibits superior thermal performance compared with the corresponding conventional nanofluid. These findings improve the understanding of coupled transport phenomena in the hybrid nanofluid and provide valuable insights for the design and optimization of advanced thermal management systems, porous cooling technologies, and renewable energy devices employing permeable wedge configurations.