Computational Analysis of Magnetohydrodynamic Flow and Shape-Factor Consequences on the Thermal Performance of Aqueous Micropolar Copper Nanofluids

This study addresses a limitation in classical models of nanofluid flow, namely, their inability to adequately capture microscale effects associated with fluid-element microrotation and local microstructural dynamics. Specifically, the effects of nanoparticle geometry and microrotation on the hydrodynamic and thermal behavior of copper (Cu)–water nanofluids flowing over a stretching surface under a transverse magnetic field are investigated. Four nanoparticle morphologies: bricks, cylinders, platelets, and blades, are considered, with water (Pr = 6.2) as the base fluid. Appropriate similarity transformations are employed to reduce the governing nonlinear partial differential equations (PDEs) to a system of ordinary differential equations (ODEs), which is solved numerically using the Runge–Kutta–Fehlberg (RKF) integration scheme. A comprehensive parametric analysis is conducted to examine the effects of the governing physical parameters on the velocity, microrotation, and temperature distributions. The results reveal that increasing the thermal radiation parameter enhances the temperature distribution for all four nanoparticle morphologies. Furthermore, comparative analysis indicates that water-based nanofluids exhibit a more pronounced temperature gradient than kerosene-based fluids under identical physical conditions. These findings highlight the importance of nanoparticle morphology and microscale rotational effects in modeling the flow and heat transfer characteristics of nanofluids.