Numerical simulation on the effect of impeller radial gap on hemodynamics and hemocompatibility of a centrifugal blood pump

Impeller radial gap is one of important parts within a blood pump, which may affect the hemodynamics and hemocompatibility. In this study, computational fluid dynamics method was performed to evaluate the impact of radial gap sizes. The volume of scalar shear stress decreased with radial gap sizes increasing. On the contrary, the residence time increased with radial gap sizes increasing, especially in the bottom gap. The hemolysis index and platelet activation status at three flow rates decreased with the increase of radial gap sizes. Compared with the hemolysis index when the radial gap size was 0.6 mm, the hemolysis index for the radial gap of 1.0 mm decreased by 27.6%, 25.4% and 21.1% from low flow rate to high flow rate, respectively. Similarly, the platelet activation status for the radial gap of 1.0 mm decreased by 13.0%, 11.5% and 9.1%, respectively. As a novelty, this study revealed that radial gap sizes can significantly influence the blood pump hemocompatibility, especially at low flow rate. In addition, the hemolysis performance can be more affected by radial gaps than that on thrombosis risk.