Spatially Varying Porosity Modulation of Cross Tetra-Hybrid Nanofluid Flow and Bioconvection in Stenosed Arteries

This work proposes a new unified multi-physics framework for blood flow analysis in a stenosed artery immersed in a spatially varied porous medium. The application of a spatially varying pore size distribution has been made in the extended Tiwari-Das model of tetra-hybrid nanofluids in conjunction with non-Newtonian Cross fluid model to consider the shearthinning characteristic of blood for the first time. The overall construction of the study involves magnetohydrodynamics, oxytactic bioconvection, Arrhenius activation energy, and nonlinear thermal radiation. The resulting dimensionless equations have been solved numerically with sufficient validation against conventional results. It can be seen from the results that tetrahybrid suspension has shown a superior performance compared to mono-, di- and tri-hybrid systems in terms of heat transfer and microorganism diffusion. Very importantly, controlling spatial porosity is the main factor behind hemodynamic resistance which demonstrates that classical constant-porosity models underestimate wall shear stress and heat transfer rates. Quantitatively, the Cross-fluid model shows 7 - 9% higher skin friction compared to the Newtonian model for all considered parameters. In addition, increasing the Biot number from 0.1 to 0.3 results in approximately 180-190% increase in the local Nusselt number. Ultimately, the presented model provides a very realistic theoretical basis for drug delivery improvement, photothermal therapy and cardiovascular diagnosis.