Analysis of flow field and hemolysis index in axial flow blood pump by computational fluid dynamics–discrete element method

Abstract

To fully study the relationship between the internal flow field and hemolysis index in an axial flow blood pump, a computational fluid dynamics–discrete element method coupled calculation method was used. Through numerical analysis under conditions of 6000, 8000, and 10,000 r/min, it was found that there was flow separation of blood cell particles in the tip of the impeller and the guide vane behind the impeller. The flow field has a larger pressure gradient distribution, which reduces the lift ratio of the blood pump and easily causes blood cell damage. The study shows that the hemolysis index obtained by the computational fluid dynamics—discrete element method is 4.75% higher than that from the traditional computational fluid dynamics method, which indicates the impact of microcollision between erythrocyte particles and walls on hemolysis index and also further verifies the validity of the computational fluid dynamics–discrete element coupling method. Through the hydraulic and particle image velocimetry experiments of the blood pump, the coincidence between numerical calculation and experiment is analyzed from macro and micro aspects, which shows that the numerical calculation method is feasible.

Equivalent Scalar Stress Formulation Taking into Account Non-Resolved Turbulent Scales

“…With this study we do not want to present an improved blood damage modeling in general, but rather point out that any prediction model could be affected by systematic errors if the turbulent flow field (resolved and unresolved) is not used entirely for the equivalent scalar stress calculation as it is done today. 6 , 9 , 18 , 53 , 60 This means that the conclusions of this study could be important for the development of new damage models. Only the consideration of all stresses, whether resolved or modeled, can lead to a reliable result in a future prediction model.…”