Symmetry‐based analysis of nonlinear mixed convection in 3D EMHD nano‐Carreau fluid flow with Riga stretched surface effects and multi‐physical interactions

This study presents a comprehensive investigation into the dynamics of an electrically magneto‐hydrodynamic (EMHD) nano‐Carreau fluid under nonlinear mixed convection. We develop a 3D steady‐state framework that incorporates various influential factors such as nonuniform heat source‐sink terms, nonlinear thermal radiation, Joule heating, and chemical reactions, along with the effects of a Riga stretched surface. Through rigorous analysis, we explore the impact of thermophoretic and Brownian motions on flow patterns and stagnation point velocities. Our study encompasses scenarios involving a Riga stretching sheet, EMHD phenomena, porous media, suction‐injection processes, and diverse slip conditions (momentum, heat, volume fractions), in conjunction with chemical reactions. By employing symmetry transformations, we transform complex partial differential equations (PDEs) into more manageable ordinary differential equations (ODEs), facilitating effective numerical solutions using the Lobatto IIIa bvp4c method in Matlab. The findings are presented through detailed graphical representations and comparative tables. Key findings include the observation that elevated Hartmann numbers contribute to reduced velocity yet enhanced temperature profiles, influenced by factors such as nonuniform heat distribution, thermal radiation, and viscous dissipation. Additionally, concentration profiles exhibit a diminishing trend with increased Lewis numbers, chemical reactions, and specific slip parameters.