Parametric Comparison of Thermally Radiative and Chemically Reactive Al ₂ O ₃ –H ₂ O and CuO–H ₂ O Nanofluid Flow over an Inclined Riga Plate

Introduction: The Riga plate, capable of generating a Lorentz force through the interaction of electric and magnetic fields, can be used to control fluid motion and enhance heat transfer. This study presents a parametric comparison of Al2O3–H2O and CuO–H2O nanofluid flow over an inclined Riga plate, incorporating the combined effects of thermal radiation and homogeneous chemical reactions, which have not been jointly addressed in earlier investigations. Method: The Hamilton–Crosser nanofluid model is employed to accurately estimate the effective thermophysical properties of the nanofluids. Governing equations for unsteady, oscillatory boundary layer flow are formulated and analytically solved using the perturbation method, ensuring convergence throughout the analysis. Results: A detailed examination of transport characteristics, including momentum, thermal, and concentration boundary layer thickness, is analyzed graphically. Additionally, engineering performance indicators such as skin friction coefficient, Nusselt number, and Sherwood number are computed using MATLAB (R2020b). The results demonstrate that increasing the nanoparticle volume fraction enhances heat and mass transfer rates while reducing wall shear stress. An increase in plate inclination angle and magnetic field strength leads to thickening of the momentum boundary layer, whereas stronger chemical reaction rates reduce the concentration boundary layer. Discussion: The novelty of this work lies in the integrated analysis of unsteady oscillatory nanofluid flow over an inclined Riga plate by simultaneously accounting for thermal radiation and homogeneous chemical reaction, an approach not explored in earlier studies. Conclusion: In addition, the comparative evaluation of CuO-H2O and Al2O3-H2O nanofluids under identical conditions provides new insights into their distinct roles in modifying momentum and thermal boundary layers. The key findings also contribute to the understanding of flow control and chemical reactions in industrial processes, offering potential pathways for optimizing performance in various engineering applications.