Modeling and simulation of Soret–Dufour and bioconvective effects in micropolar nanofluid stagnation-point flow over a Riga plate

This study investigates the stagnation-point flow of a micropolar nanofluid over a Riga plate in the presence of Soret–Dufour effects and bioconvection induced by motile microorganisms. The mathematical model incorporates the influences of electromagnetic forcing, thermal radiation, heat generation/absorption and chemical reaction on the transport phenomena. By employing suitable similarity transformations, the governing partial differential equations are reduced to a system of coupled nonlinear ordinary differential equations, which are solved numerically using the Runge–Kutta fourth-order method combined with a shooting technique. Furthermore, the graphical and tabular representations analyze the impacts of several relevant parameters on velocity, microrotation, temperature, concentration profiles and the engineering quantities such as skin friction, couple stress, Nusselt number, Sherwood number and motile density fields. The results reveal that the modified Hartmann number significantly enhances the fluid velocity, whereas the Riga plate decay parameter suppresses it. Temperature is found to increase with radiation, Dufour number, heat generation parameter, and Biot number, while it decreases with increasing Prandtl number. Furthermore, the Soret number enhances nanoparticle concentration, whereas higher Schmidt number and chemical reaction parameter reduce it. The density of motile microorganisms decreases with increasing bioconvection Lewis number, Péclet number and microorganism difference parameters. The numerical scheme's correctness is verified with the previously published literature and shows excellent agreement. The novelty is that it presents a unified mathematical framework that captures the coupled interactions among momentum, heat, mass and microorganism transport mechanisms. The findings of this study provide valuable insights into the control of heat, mass and microorganism transport in electromagnetically driven micropolar nanofluid systems with potential applications in biotechnology, microfluidics and advanced thermal management technologies.