Hybrid SWCNT/MWCNT Nanofluid Flow Over Porous Surfaces With Thermal Radiation and Microbial Bioconvection Under Soret–Dufour Coupling

The present investigation examines the magnetohydrodynamic behavior of a SWCNT–MWCNT/water hybrid nanofluid flowing over porous configurations, specifically cones, wedges, and flat plates, in the presence of thermal radiation and microbial bioconvection incorporating coupled Soret–Dufour effects. The governing nonlinear partial differential equations are reduced to a system of ordinary differential equations through suitable similarity transformations and subsequently solved using a robust boundary value problem solver. The analysis demonstrates that an increase in magnetic field intensity and Forchheimer resistance substantially decelerates the fluid motion, leading to a velocity reduction of approximately 25%–30%, while concurrently intensifying thermal and concentration fields by nearly 15%–22% due to enhanced Lorentz force interactions. The combined influence of thermal radiation and the Dufour effect significantly promotes heat transport, resulting in a 10%–18% elevation in temperature, whereas porous medium characteristics further facilitate this enhancement. Conversely, elevated magnetic and thermal parameters contribute to a decline in nanoparticle concentration and micro‐organism density by about 12%–20%, indicating regulated particle dispersion and attenuation of bioconvective strength. Geometrical variations play a crucial role, with the flat plate exhibiting comparatively higher velocity profiles, while the cone geometry experiences greater resistance due to curvature effects. Furthermore, microbial dynamics are observed to considerably influence flow stability and mass transfer characteristics. Overall, the study elucidates the complex interplay among electromagnetic forces, thermal radiation, cross‐diffusion mechanisms, and microbial activity, offering valuable insights for the design and optimization of hybrid nanofluid systems in advanced thermal management, biomedical engineering, microfluidics, and environmental applications.