Thermal Investigation of Casson Nanofluid Flow Externally to a Rotating Cylinder Under Resistive Heating and Thermal Radiations

Abstract This study examines the thermal and solutal transport in a Casson nanofluid flowing around a vertically rotating cylinder, under conditions of mixed convection and nonlinear thermal radiation. The work further integrates the Buongiorno nanofluid model to account for thermophoresis and Brownian motion phenomena, while additionally including activation energy (AE), nonuniform heat source/sink, and magnetic field interactions. By using similarity variables, the governing momentum, energy, and mass transport partial differential equations (PDEs) are reduced to a system of ordinary differential equations (ODEs), which are numerically solved using the MATLAB bvp4c method. The effects of various physical parameters on the velocity, concentration, and temperature field are analyzed. Key findings indicate that mixed convection and buoyancy forces enhance the axial flow, whereas Reynolds number and Casson rheology exhibit a resistive influence on both axial and tangential velocities. The Nusselt number increases by approximately 30% as the radiation parameter rises, significantly enhancing heat transfer. The Sherwood number grows by about 16% with increasing Schmidt number, indicating stronger mass transfer. Activation energy plays a crucial role in sustaining solutal concentration by mitigating chemical reaction losses.