Thirupathi Thumma

Hybrid nanofluids (HNFs) have become important for improving heat transfer in various engineering fields, especially in rotating cylinders, energy conversion systems and efficient heat exchangers. Motivated by the need to elevate heat transfer efficacy, this research explores the thermal transport behavior of a hydromagnetic HNF composed of methanol enriched with nanoparticles coursing over a stretchable cylindrical surface. The flow regime is defined by the inclusion of viscous and Joule heating, linear thermal radiation and slip-flow phenomena, governed by velocity slip and temperature jump conditions (Smoluchowski) at the boundary. The model also integrates the role of variable electrical conductivity, dynamic viscosity and thermal conductivity, critical factors inspired by their real-world relevance in temperature-sensitive microfluidic systems, energy-efficient thermal insulation and smart fluidic cooling technologies. The nonlinear partial differential equations were converted into ordinary differential equations (ODEs) through similarity transformations, then solved with the reliable fourth-order Runge–Kutta method and a shooting technique. Graphical insights elucidate how key parameters such as thermal radiation intensity, viscous heating and boundary slip phenomena intricately influence velocity and temperature fields. Notably, enhanced fluid momentum is associated with higher Maxwell slip and Reynolds numbers, while elevated Eckert and radiation parameters amplify thermal diffusion. Quantitatively, the wall shear stress exhibits a 23.6% reduction with increasing magnetic parameter (M) and a 17.8% decrease under suction enhancement (S), while HNFs outperform conventional nanofluids in drag reduction. The HNF achieves a Nusselt number (Nu) that is up to 8.71% higher than the conventional Nanofluid (NF) at [Formula: see text], confirming its superior heat transfer capability. Validation against established benchmark scenarios confirms the robustness and accuracy of the numerical formulation. This study is vital for advancing magnetic-assisted thermal regulation and thermal energy storage solutions in high-performance engineering systems where precise thermal control is critical for operational efficiency.

Couple‐stress fluids characterize the rheological behaviour of microstructure suspensions such as polymeric melts, lubricants, biological fluids, and colloidal mixtures. These fluids exhibit particle‐scale rotations and size‐dependent characteristics that significantly affect the transfer of momentum and energy. Such behaviours become especially pronounced near curved or cylindrical surfaces, which are central to industrial processes like coating, extrusion, geothermal drilling, and heat exchange systems. Under high‐temperature or chemically reactive conditions, radiative heat transfer emerges as a major mode of energy transport, while the Arrhenius‐type activation energy dictates the rate of species conversion in catalytic reactors, polymerization mechanisms, and reactive fluid flows. This interplay calls for a unified analysis that considers both radiative and activation‐controlled effects. The present study investigates the unsteady transport phenomena of a non‐Newtonian fluid past an infinitely long vertical cylinder, incorporating the combined effects of thermal radiation and Arrhenius activation energy. The nonlinear governing equations for the flow field, thermal profile, and species distribution are discretized in the radial direction using second‐order central finite differencing and integrated over time via the method of lines to ensure numerical stability and accuracy. Computational outcomes reveal that the couple‐stress parameter () accelerates the velocity distribution, thermal profile, and species distribution. Increasing the magnetic parameter () and decreasing the Darcy parameter () reduces velocity but increases temperature and concentration. The radiation parameter significantly enhances fluid temperature, whereas increasing the activation parameter promotes species accumulation. Comparisons with earlier works confirm the validity of the present formulation, and the generated insights are pertinent to thermal and industrial applications such as polymer extrusion, catalytic processing, electronic cooling, and biophysical fluid transport, where microstructural and thermo‐chemical interactions play a decisive role.

In recent years, upper convected Maxwell (UCM) fluids have garnered considerable attention due to their ability to model memory‐dependent behaviors of polymeric liquids and viscoelastic materials, making them indispensable in industries, such as polymer extrusion, biomedical drug delivery, food processing, and lubrication technology. Thus, this study presents the complex thermofluidic behavior of a UCM fluid near a stagnation region. The proposed advanced two‐phase nanofluid flow model integrates the dynamic effects of a transverse magnetic field, radiative thermal flux, Arrhenius‐type activation energy, and multi‐level velocity and thermal slip boundary constraints. The initial set of nonlinear PDEs governing the fluid's momentum, energy, and mass transfer is transformed into a system of coupled ordinary differential equations using similarity transformations. The spectral local linearization method (SLLM) is employed due to its suitability for capturing complex nonlinear interactions. The analysis reveals that the Lorentz force, associated with a magnetic field, resists free fluid flow for precise control over the velocity field. Enhancement in the stretching ratio boosts the momentum transport, intensifying the boundary layer thickness. The findings of this investigation serve as a foundation for optimizing industrial and biomedical processes, thermal regulation in polymer manufacturing, and microfluidic reactors, thereby improving heat transfer in magnetically actuated smart devices and controlled chemical delivery systems in biomedical engineering.