Numerical flow simulations that analyze the turbulent flow characteristics within a turbopump are important for optimizing the efficiency of such machines. In the case of ventricular assist devices (VADs), turbulent flow characteristics must be also examined in order to improve hemocompatibility. Turbulence increases the shear stresses in the VAD flow, which can lead to an increased damage to the transported blood components. Therefore, an understanding of the turbulent flow patterns and their significance for the numerical blood damage prediction is particularly important for flow optimizations in VADs in order to identify and thus minimize flow regions where blood could be damaged due to high turbulent stresses. Nevertheless, the turbulence occurring in VADs and the local turbulent structures that lead to increased turbulent stresses have not yet been analyzed in detail in these machines. Therefore, this study aims to investigate the turbulence in an axial VAD in a comprehensive and double tracked way. First, the flow in an axial VAD was computed using the large‐eddy simulation method, and it was verified that the majority of the turbulence was directly resolved by the simulation. Then, the turbulent flow state of the VAD was quantified globally. For this purpose, a self‐designed evaluation method, the power loss analysis, was used. Subsequently, local flow regions and flow structures were identified where significant turbulent stresses prevail. It will be shown that the identified regions are universal and will also occur in other axial blood pumps as well, for example, in the HeartMate II.

中文翻译：

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心室辅助装置中的湍流和湍流结构——使用大涡模拟的数值研究

分析涡轮泵内湍流特性的数值流动模拟对于优化此类机器的效率非常重要。对于心室辅助装置 (VAD)，还必须检查湍流特性以提高血液相容性。湍流会增加 VAD 流中的剪切应力，这会导致对输送的血液成分的损坏增加。因此，了解湍流模式及其对数值血液损伤预测的重要性对于 VAD 中的流动优化尤为重要，以便识别并因此最小化血液可能因高湍流应力而受损的流动区域。尽管如此，尚未在这些机器中详细分析 VAD 中发生的湍流和导致湍流应力增加的局部湍流结构。因此，本研究旨在以综合和双轨方式研究轴向 VAD 中的湍流。首先，使用大涡模拟方法计算轴向 VAD 中的流动，并证实大部分湍流由模拟直接解决。然后，全局量化 VAD 的湍流状态。为此，使用了一种自行设计的评估方法，即功率损耗分析。随后，在显着湍流应力占优势的地方确定了局部流动区域和流动结构。将表明所识别的区域是通用的，并且也将出现在其他轴向血泵中，