Thermal transport in radiative MHD Casson nanofluid flow over an exponentially stretching permeable sheet with Joule heating and viscous dissipation

This paper extends the classical model of radiative mixed convection flow of a Casson nanofluid over an exponentially stretching permeable surface by incorporating the effects of viscous dissipation and Joule heating. The presence of heat generation due to fluid friction and electrical resistance significantly alters the thermal behavior of electrically conducting non-Newtonian nanofluids, particularly under strong magnetic field conditions. By employing suitable similarity transformations, the governing nonlinear partial differential equations are reduced to a coupled system of nonlinear ordinary differential equations, which is solved numerically using Mathematica software. The influences of the Casson parameter, Magnetic parameter, Radiation parameter, Prandtl number, viscous dissipation parameter, Joule heating parameter, Brownian motion parameter and Thermophoresis parameter on the velocity, temperature, concentration and heat transfer characteristics are examined over physically realistic parameter ranges. Numerical results reveal that increasing the viscous dissipation parameter from Ec = 0 to 3 and the Joule heating parameter from Jh = 0 to 3 decreases the fluid temperature, while enhancing the local Nusselt number by nearly 16–32%, depending on the selected parameter combination. In contrast, higher Prandtl number values improve the rate of surface heat transfer, whereas thermal radiation promotes temperature enhancement within the boundary layer. These findings provide deeper insight into heat transport mechanisms in Casson nanofluid flows and are relevant to thermal management systems, energy conversion devices and industrial processes involving electrically conducting non-Newtonian fluids.