Investigation of hemocompatibility and vortical structures for a centrifugal blood pump based on large-eddy simulation

Abstract

The evolution of complex flow structures has a large impact on the hemocompatibility of the centrifugal blood pump. In this study, the hemodynamic performance and the hemocompatibility of a centrifugal blood pump are investigated based on large-eddy simulation (LES). Comparisons are conducted between the LES results and the results predicted by the renormalization group (RNG) k−ε model and delayed detached eddy simulation (DDES) methods. The local trace criterion is utilized to analyze the vortical structures within the blood pump. Results show that the tip leakage vortex, the Taylor–Couette flow, and the flow separation are the most important flow structures in the blood pump. These structures have a significant influence on the hemodynamic performance and hemocompatibility. Quantitative comparison between the hemodynamic performance and the hemocompatibility is conducted between DDES, RNG k−ε, and LES results. Little difference is shown between DDES and LES results, while the RNG k−ε model tends to underestimate the pressure and hemolysis due to adopting the steady-state approach, and the assumption of isotropy and equilibrium turbulence transport. In detail, the accuracy of RANS in predicting the strength of the main vortical structures is insufficient, which tends to underestimate the leakage vortex strength and overestimate the Taylor vortex strength. Furthermore, an analysis of the relationship between hemocompatibility and vortical structures indicates that the interaction between the boundary layer and the vortical structures, such as leakage vortex and Taylor vortex, induces more blood damage, while the blood damage caused by vortical structures in the mainstream is limited.