Entropy optimization of micropolar nanofluid flow through a porous microchannel with Darcy–Forchheimer phenomenon using differential transform method: An ANOVA–Taguchi approach

This study systematically investigates the impact of key physical parameters on entropy generation and thermal behaviour in a micropolar nanofluid flowing through a horizontal microchannel using the ANOVA–Taguchi method. The Buongiorno model is employed to represent nanoparticle transport mechanisms accurately, including Brownian motion and thermophoresis. The analysis also incorporates the effects of magnetic field, fluid suction/injection, and wall boundary conditions. The presence of a porous medium is modelled using the Darcy–Forchheimer theory, while micropolar fluid theory accounts for microstructural effects through microrotation and microinertia. The resulting nonlinear governing equations are resolved numerically using the fourth–fifth order Runge–Kutta–Fehlberg method and validated via the differential transform method to ensure accuracy. The findings indicate that the material parameter increases microrotation in the upper region of the channel but reduces in the lower region, whereas the microinertia parameter exhibits the opposite trend. Higher values of the material parameter also lead to reduced entropy generation, indicating improved thermodynamic performance. Optimization analysis identifies a maximum thermal transfer rate of 1.09233 for the system. According to the ANOVA results, the Prandtl number is the most influential parameter, contributing 79.73% to the total effect on entropy generation, while the Darcy number has a minimal influence of 0.07%. These results highlight the significant role of fluid thermal properties and microstructural parameters in controlling entropy generation and heat transfer in micropolar nanofluid flows through porous microchannels.