Electroosmotic Transport and Entropy Generation in ZnO-Williamson Nanoblood Flow through a Converging/Diverging Tapered Stenosed Artery

Electroosmotic transport and entropy generation play a decisive role in regulating efficiency, stability, and energy cost of non-Newtonian nanoblood flows in stenosed arteries, particularly with tapered geometries. This study develops a unified model to analyze ZnO–Williamson nanoblood flow through a stenosed artery with converging, diverging, and non-tapered configurations, incorporating electroosmosis, viscous dissipation, and entropy production. The arterial walls are assumed to be electrically charged with a no-slip condition to induce electroosmotic propulsion along the endothelial surface. The partial differential equations are nondimensionalized to a coupled system of nonlinear ordinary differential equations, which are solved numerically using a MATLAB-based shooting technique. Parametric investigation is conducted for Brinkman, Grashof, and Weissenberg numbers, ZnO fractional volume, volumetric flow rate, and Helmholtz–Smoluchowski velocity to quantify their influences on axial velocity, wall shear stress, impedance resistance, temperature distribution, entropy generation, Bejan number, and streamline topology. The axial velocity decreases radially with increasing Brinkman number for all arterial geometries. Increasing ZnO nanoparticles improves thermal transport owing to enhanced effective thermal conductivity but simultaneously elevates entropy generation due to increased viscous dissipation. Higher Weissenberg numbers suppress entropy production by promoting elastic stress redistribution and lowering shear-induced irreversibility. Impedance resistance decreases with increasing stenosis height but increases with stenosis shape parameter and ZnO fractional volume. Streamline analysis shows that buoyancy and viscoelasticity significantly distort flow near the stenosis, while increasing electroosmotic velocity stabilizes streamlines, suppresses recirculation, and reduces local shear stress and pressure fluctuations. In conclusion, electroosmotic actuation is most effective in reducing flow resistance in the converging tapered artery, particularly at lower ZnO volume fractions. Overall, the findings highlight the potential of optimized electroosmotic actuation and controlled nanoparticle loading to minimize thermodynamic losses, regulate shear stress, and improve flow uniformity in stenosed vessels, with promising implications for electro-assisted drug delivery, nanotherapeutics, and bio-inspired vascular microfluidic systems.