Significance of thermal radiation in a non-Newtonian (Reiner-Rivlin) model past a cylindrical surface with application in a thermal management system

The study of thermal radiation in fluid mechanics has gained considerable attention due to its pivotal role in heat and mass transfer processes across various industrial and engineering applications. Building on this motivation, this study emphasizes how thermal radiation affects the transport of heat and mass in the flow. Specifically, it explores the stagnation-point flow behavior of a Reiner–Rivlin type non-Newtonian fluid that arises due to a stretching cylindrical surface. The analysis is extended to incorporate bioconvective transport due to motile microorganisms, Soret and Dufour effects, and Joule heating effects. The boundary conditions assume prescribed wall temperature and solute concentration, enabling the derivation of the similarity variables. Curvature effects are introduced through a dimensionless curvature parameter, defined in terms of the inverse of the cylinder radius, which quantifies deviations from a flat plate configuration. This parameter is varied to investigate its impact on the structure of stagnation-point flow and thermal transport. The transformed nonlinear ordinary differential equations are numerically solved using the Chebyshev Collocation method. Validation of the computational results is performed by comparing them with existing solutions under certain limiting cases. The study further investigates the interplay between thermal radiation and microorganism motility, which occurs through the radiation-induced temperature rise influencing bioconvective density gradients and microorganism distribution. Parametric studies are carried out to examine how key factors such as curvature, thermal radiation, bioconvective parameters, diffusion coefficients, and Reiner–Rivlin fluid characteristics affect flow profiles, temperature and concentration distributions, motile microorganism density, and skin friction. The findings reveal that an increase in thermal radiation leads to a rise in temperature distribution and modifies the bioconvective flow field. These insights are vital for optimizing the design of systems involving non-Newtonian fluids in energy, biomedical, and microfluidic applications.