Numerical investigation of blood rheology in ventricular assist devices: effects on performance and shear stress

This study evaluates whether Newtonian models can replace non-Newtonian models in ventricular assist device (VAD) simulations. Five rheological models were compared in an axial-flow VAD using ANSYS CFX. High-shear conditions (92% > 300 s^-1 rendered non-Newtonian effects negligible, with errors <1% for pressure rise, efficiency, and torque. Wall shear stress variations were minimal (±5 Pa) and below hemolysis thresholds. Newtonian models suffice for performance predictions in high-shear regions, reducing computational costs by 30-50%. However, localized non-Newtonian effects in stagnation zones may need analysis for thrombogenicity. These findings streamline VAD design without compromising accuracy.