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Development and validation of a computational fluid dynamic methodology for pulsatile blood pump design and prediction of thrombus potential.

机译：开发和验证脉动血泵设计和血栓潜力预测的计算流体动力学方法。

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摘要

A computational fluid dynamics (CFD) methodology is developed to assess the hydrodynamic and hemodynamic performance of a positive displacement left ventricular assist device (LVAD). The pulsatile behavior of the device is developed by implementing valve and piston models to simulate the dynamic effects of valve closure and chamber compression. High fidelity unstructured meshes along with an implicit-LES (Large Eddy Simulation) approach to turbulence are used to model the transitional to low Reynolds number turbulent flows. Grid, time step, and piston modeling studies are performed to evaluate the computational methodology. The thrombosis susceptibility potential (TSP) is developed to gain insight into the device hemodynamic performance and elucidate regions of consistently low wall shear as potential deposition sites. The area- and time-integrated TSP value allowed a quantitative comparison as a means of ranking device performance. A scaling analysis is performed to study the effects of geometric scale on thrombus deposition. Several design variants are analyzed and validated against in vitro PIV data by comparing velocity and wall shear stress measurements. Finally, various mechanical valve types and valve orientations are assessed.;The computational results compare well against in vitro measurements, demonstrating similar mitral jet and chamber rotational patterns within the device. These comparisons give confidence that CFD adequately predicts the device flow field, including aspects which are not easily measured experimentally, in particular the device wall shear. A scaling analysis demonstrated which device geometric and flow field parameters are important for device scaling. The CFD results show that maintaining Reynolds and Strouhal number when geometrically scaling from the 70 cc to the 50 cc device results in a less thrombogenic chamber flow. Design comparisons indicate that the addition of a curved front face to the chamber design increases the TSP of the modified device. Finally, the use of Bjork-Shiley mono-strut valves in the mitral port yields increased wall washing within the device.
机译：开发了一种计算流体动力学（CFD）方法来评估正排量左心室辅助设备（LVAD）的流体动力学和血液动力学性能。通过执行阀门和活塞模型来模拟阀门关闭和腔室压缩的动态影响，从而开发了设备的脉动特性。高保真非结构化网格以及用于湍流的隐式LES（大涡模拟）方法可用于对低雷诺数湍流的过渡过程进行建模。进行网格，时间步长和活塞建模研究以评估计算方法。血栓形成易感性（TSP）的开发旨在深入了解器械的血液动力学性能，并阐明始终处于低壁剪切状态的区域作为潜在的沉积部位。面积和时间积分的TSP值允许进行定量比较，以对设备性能进行排名。进行定标分析以研究几何标度对血栓沉积的影响。通过比较速度和壁切应力测量结果，针对体外PIV数据对几种设计变体进行了分析和验证。最后，评估了各种机械瓣膜类型和瓣膜方位。计算结果与体外测量结果进行了很好的比较，证明了装置内的二尖瓣喷射和腔室旋转模式相似。这些比较使人相信CFD可以充分预测设备的流场，包括不容易通过实验测量的方面，特别是设备壁的剪切力。缩放分析显示了哪些设备几何和流场参数对于设备缩放很重要。 CFD结果表明，当从70 cc缩放到50 cc装置时，保持雷诺数和斯特劳哈尔数在几何上成比例会导致较少的血栓形成室流量。设计比较表明，在腔室设计中添加弯曲的正面会增加修改后的设备的TSP。最后，在二尖瓣口使用Bjork-Shiley单支柱阀会增加设备内的洗墙次数。

著录项

  • 作者

    Medvitz, Richard Brian.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Engineering Biomedical.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 227 p.
  • 总页数 227
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;机械、仪表工业;
  • 关键词

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