Role of Nanoparticle Shape in Enhancing Heat Transfer: A Comparative Study of Platelet and Blade MoS ₂ Nanofluids

In this study, the three-dimensional flow and heat transfer characteristics of a nanofluid are investigated by considering both platelet- and blade-shaped molybdenum disulfide (MoS 2 ) nanoparticles dispersed in water, along with variable viscosity effects, over a stretching surface embedded in a Darcy porous medium. The influence of partial slip at the boundary on the flow behavior is also examined. The presence of nanoparticles, combined with slip effects, is found to suppress the tangential velocity and reduce fluid suction at the surface, while inducing slight radial motion and significantly modifying the temperature distribution. The governing equations are transformed into a dimensionless form using suitable similarity transformations and solved numerically via the fourth-order Runge-Kutta-Fehlberg method with a shooting technique. The results reveal that increasing porosity and velocity slip reduces the fluid velocity. A comparative analysis demonstrates that platelet-shaped nanoparticles consistently yield higher heat transfer rates than blade-shaped particles. For instance, the Nusselt number for platelet particles is significantly higher than that of blade-shaped particles under identical conditions, indicating superior thermal performance. These findings highlight the critical role of nanoparticle geometry in optimizing heat transfer and suggest that platelet-shaped MoS 2 nanoparticles are more effective for advanced thermal management applications.