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A Numerical Modeling for Characteristics of Blood Trauma in Blood Pumps

초록 (요약문)

In the present study, simulations of the blood damage caused by centrifugal blood pumps were performed, various existing hemolysis models were comparatively verified, and a new model was proposed. Steady-state three-dimensional computational fluid dynamics simulations were performed using the Eulerian approach to observe the blood damage distribution within the control volume. 1D analysis, 2D channel analysis, the cannular, the FDA benchmark blood pump, and two commercial pumps (CAPIOX and BP-80) were set as the validation cases, and simulations were performed. As a result of the analysis results, the power-law-based model confirmed that the effective time model shows good agreement with the relative hemolysis index value. However, the power-law-based model is defined using empirical coefficients based on blood species; it lacks an explanation regarding the mechanism of hemolysis and the physical properties of red blood cells. A viscoelastic model was applied among the strain-based models to overcome this limitation. The viscoelastic model considers the viscoelastic behavior of the red blood cell membrane. As with the power-law-based model, a residence time model and an effective time model were constructed for the viscoelastic model and compared each experimental result. In addition to temporal modeling, the wall model was developed to predict hemolysis near walls under coarse grid resolution. Therefore, the calculation load’s dependence on the grid size can be significantly reduced while maintaining the simulation accuracy with the application of the wall model. In modeling thrombosis, a simulation was conducted by applying a biochemical model. For this, 7 species were considered, and the volume source term and the chemical species flux of the damaged vessel wall were modeled. By controlling the chemical reaction rate, the results of the developed model were able to agree with the experimental results. In this study, two models were proposed: one, a blood damage index model for accessing hemolysis with respect to small-sized load, and two, a platelet thickness model for accessing thrombosis based upon the chemical species model and the modification of chemical reaction rate coefficient of various catalysts. Based on this study, a designer can perform a CFD analysis of a three-dimensional geometry when designing a medical device and predict the expected amount of hemolysis and thrombosis in advance. Thus, it will be possible to review various design factors and suggest modifications to reduce blood damage. For the above-stated reasons, this study can be expected to be used as a basis for future domestic medical device development.

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