Irreversibility analysis of MHD Casson nanofluid transport over a nonlinear stretching sheet.

This study investigates magnetohydrodynamic (MHD) Casson nanofluid flow over a nonlinearly stretching sheet with velocity and thermal slip, porous medium, and chemical reaction effects. The governing nonlinear partial differential equations are transformed into ordinary differential equations using similarity transformations and solved numerically with MATLAB's bvp4c solver. The flow characteristics are analyzed in terms of velocity, temperature, concentration, skin friction coefficient, Nusselt number, Sherwood number, entropy generation, and Bejan number. The results show that increasing the magnetic parameter and Casson parameter (0.3-0.6) suppresses the velocity while enhancing the temperature and concentration profiles. Higher Prandtl number values reduce the fluid temperature and thermal boundary-layer thickness, while the nanoparticle concentration increases with Pr. Increasing the thermophoresis parameter (0.1-0.4) significantly increases both the temperature and nanoparticle concentration. Entropy generation is enhanced by magnetic and diffusion effects but decreases with increasing velocity slip and Casson parameter. The Bejan number attains its maximum near the stretching surface, indicating the dominance of heat transfer irreversibility, and decreases away from the wall as fluid friction irreversibility becomes more significant. The numerical results agree well with previously published limiting cases. The findings provide useful insights for optimizing heat transfer, reducing thermodynamic irreversibility, and improving the performance of polymer processing, electronic cooling, MHD pumps, and other advanced thermal management systems.