Fluid flow and heat transfer optimization in non-parallel channels are significant for microchannel cooling, lubrication mechanisms, biomedical transport, and thermal energy systems where controlling heat and momentum transfer is essential for performance optimization. Inspired by these engineering applications, this work provide a novel comparative analysis for the Jeffery–Hamel flow (J-HF) and heat transfer of pure micropolar fluid and carbon nanotube (CNT)-based hybrid nanofluids (HNFs) via convergent-divergent porous channels. The J-HF of micropolar HNFs with enhanced heat transfer features is novel contribution to the J-HF problem. The governing equations for momentum, microrotation and energy are derived using Eringen's micropolar fluid theory. Effect of thermal radiation, Eringen coupling, spin gradient viscosity, microinertia, Darcy–Forchheimer resistance, and convective cooling/heating were taken for the first time in existence literature. The Keller–Box implicit finite-difference approach is used to solve the nonlinear governing equations describing velocity, microrotation, and temperature fields. The findings show that higher spin gradient viscosity encourages angular momentum transmission.The microinertia parameter increases microrotation in divergent channels while decreasing it in convergent ones. Thermal radiation uplift the skin friction by 3.7% and the Nusselt number by 29.4%. Higher Darcy and Forchheimer numbers lower both velocity and heat transmission. The enhanced heat transfer ability of CNT-based HNF is confirmed by their overall Nusselt numbers, which are 8–15% greater than those of pure micropolar fluids. A large channel angle (divergent channel) improves heat transfer by roughly 18–22%, while reducing skin friction by roughly 11–13%.
Nasr et al. (Fri,) studied this question.