A Numerical Simulation of Reciprocating Blood Pump: Effect of Valve Movement and Leakage Flow on Hemolytic Performance

Abstract

The left ventricular assist device (LVAD) is a blood pump that boosts the pumping ability of the bottom left chamber of the heart in patients with advanced stage of heart failure. This study aims to present a detailed investigation into the hemolytic characteristics associated with an LVAD, while scrutinizing the impact of valves on blood damage in a reciprocating blood pump. To this end, a numerical approach is utilized to explore the effect of valves movement and leakage flow as the two critical causes of red blood cell damage (hemolysis) by capturing the full range of the valve motion. To predict both blood flow and the hemolysis index, corresponding time-dependent nonlinear partial differential equations are integrated into the governing formulation system. The fluid dynamic characteristics are derived from the Navier–Stokes equations, while the degree of hemolysis is determined by incorporating two additional scalar transport equations using an Eulerian transport method. To simulate valves closure, we consider different methods namely, dynamic mesh technique, viscosity valve closure model and the combination of both. The findings reveal that the hemolysis index is minimum at the inlet region and acquires its maximum value at the valves and clearance subdomains. Moreover, the results depict a favorable reduction in the hemolysis index through a simultaneous increase in frequency and decrease at a specific Reynolds number. It is observed that valves movement and valves leakage flow lead to a sensible one and two order of magnitude increase in the hemolysis index, respectively.