Comparative study of hybrid, tri-hybrid and tetra-hybrid nanoparticles in MHD unsteady flow with chemical reaction, activation energy, Soret-Dufour effect and sensitivity analysis over Non-Darcy porous stretching cylinder.

Present study investigates influence of Soret-Dufour effects on MHD unsteady flow of a tetra-hybrid nanofluid (AlO, Cu, SiO and TiO with base fluid water) within non-Darcy porous stretching cylinder. Additionally, chemical reaction, activation energy, and heat generation are considered. This research contributes to the understanding of how these nanofluids can optimize heat and mass transfer process in applications such as advanced cooling systems, solar collectors, biomedical devices, and chemical reactors. Tetra-hybrid nanofluids are selected as per novel aspects for their exceptional ability to adapt their properties for diverse applications, including advanced thermal management systems and scenarios requiring high thermal and electrical conductivity. The comparison between hybrid, tri-hybrid, and tetra-hybrid nanofluids serves to evaluate how increasing complexity and diversity in nanoparticle combinations impact thermal and flow characteristics. The prevailing PDE's undergo transformation into nonlinear ODE's through the utilization of similarity variables and numerically solved using fifth order Runge-Kutta Fehlberg method with shooting method. It is established that rising unsteady parameter values result in increasing velocity profile and rising shape factor parameter result in higher heat transfer. Specifically, the Nusselt number increases by 24 % in the tri-hybrid and 11 % in the tetra-hybrid with a higher Soret number, whereas the Sherwood number decreases by 38 % in the tri-hybrid and 26 % in the tetra-hybrid nanofluid. Employing sensitivity analysis, this study also aims to investigate impact of output responses such as local Nusselt number and local Sherwood number on input parameter Dufour number, Soret number and chemical reaction parameter for tri-hybrid and tetra-hybrid nanofluid. It is found out that Dufour number in tetra-hybrid nanofluid has the more significant impact on the Nusselt number, whereas the Soret number predominantly affects the Nusselt number in tri-hybrid nanofluid. These findings underscore the potential of tetra-hybrid nanofluid in enhancing the performance of various industrial and environmental processes.