Impact of external pressure and nanoparticles on heat transfer in couple stress Oldroyd-B fluid: A numerical study

This study investigates the flow characteristics of an Oldroyd-B Couple Stress Fluid (OBCSF) under external pressure within the framework of the Buongiorno model. Understanding this dynamic behavior is crucial for advancements in nanofluid technology and non-Newtonian fluid mechanics. The complex behavior of non-Newtonian fluids arises from internal microstructural effects, which are well described by the Oldroyd-B model. The additional influence of external pressure and nanoparticle effects further complicates the flow dynamics, necessitating a comprehensive numerical analysis to understand their combined impact. The governing equations for continuity, momentum, heat transfer, and concentration are formulated and solved numerically under appropriate boundary conditions for the coupled Oldroyd-B fluid and Buongiorno model. A numerical approach integrating the finite difference and finite element methods is employed to analyze the system under varying external pressure conditions and different nanoparticle volume fractions. The numerical simulations reveal significant variations in velocity profiles, temperature distribution, and concentration due to changes in external pressure. The presence of nanoparticles alters viscosity and thermal conductivity, thereby influencing heat transfer within the fluid. Furthermore, the couple stress parameter introduces additional complexity, exhibiting shear-thinning or shear-thickening behavior depending on its magnitude, which in turn affects the overall flow characteristics. These findings underscore the intricate interplay between external pressure, nanoparticle dynamics, and the non-Newtonian properties of the fluid. The study has practical implications for optimizing heat transfer processes in nanofluid-based systems and enhancing the efficiency of industrial applications involving complex fluid dynamics. The insights gained from this research contribute to the design and improvement of technologies that rely on nanofluid mechanics and the distinctive properties of non-Newtonian fluids. • Numerical investigation of Oldroyd-B nanofluids under external pressure using the Buongiorno model. • Significant effects of nanoparticle volume fraction on velocity, temperature, and concentration profiles. • Complex fluid behavior due to shear-thinning or shear-thickening induced by the couple stress parameter. • Practical insights for optimizing heat transfer processes in nanofluid-based industrial applications.