Purpose

Modeling of hemolysis due to fluid stresses faces significant methodological challenges, particularly in geometries with turbulence or complex flow patterns. It is currently unclear how existing phenomenological blood-damage models based on laminar viscous stresses can be implemented into turbulent computational fluid dynamics simulations. The aim of this work is to generalize the existing laminar models to turbulent flows based on first principles, and validate this generalization with existing experimental data.

Methods

A novel analytical and numerical framework for the simulation of flow-induced hemolysis based on the intermittency-corrected turbulent viscous shear stress (ICTVSS) is introduced. The proposed large-eddy simulation framework is able to seamlessly transition from laminar to turbulent conditions in a single flow domain by linking laminar shear stresses to dissipation of mechanical energy, accounting for intermittency in turbulent dissipation, and relying on existing power-law hemolysis models. Simulations are run to reproduce previously published hemolysis data with bovine blood in a benchmark geometry. Two sets of experimental data are relied upon to tune power-law parameters and justify that tuning. The first presents hemolysis measurements in a simple laminar flow, and the second is hemolysis in turbulent flow through the FDA benchmark nozzle. Validation is performed by simulation of blood injected into a turbulent jet of phosphate-buffered saline, with modifications made to account for the local concentration of blood.

Results

Hemolysis predictions are found to be very sensitive to power-law parameters in the turbulent case, though a set of parameters is presented that both matches the turbulent data and is well-justified by the laminar data. The model is shown to be able to predict the general behavior of hemolysis in a second turbulent case. Results suggest that wall shear may play a dominant role in most cases.

Conclusion

The ICTVSS framework of generalizing laminar power-law models to turbulent flows shows promise, but would benefit from further numerical validation and carefully designed experiments.

中文翻译：

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FDA基准喷嘴几何形状中的大涡流模拟可预测溶血。

目的

由于流体应力造成的溶血建模面临着重大的方法论挑战，尤其是在具有湍流或复杂流型的几何形状中。目前尚不清楚如何将现有的基于层流粘性应力的现象学血液损害模型应用于湍流计算流体动力学模拟。这项工作的目的是基于第一原理将现有的层流模型推广到湍流，并利用现有的实验数据验证这种推广。

方法

介绍了一种基于间歇校正的湍流粘性剪切应力（ICTVSS）的流动诱导溶血模拟的新型分析和数值框架。通过将层流切应力与机械能耗散联系起来，考虑了湍流耗散的间歇性，并依靠现有的幂律溶血模型，提出的大涡模拟框架能够在单个流域中从层流状态无缝过渡到湍流状态。进行模拟以使用基准几何图形用牛血再现以前发布的溶血数据。依靠两组实验数据来调整功率定律参数并证明该调整的合理性。第一个是简单层流中的溶血测量，第二个是通过FDA基准喷嘴的湍流中的溶血。

结果

尽管在湍流情况下溶血预测对幂律参数非常敏感，但是提出了一组既与湍流数据匹配又由层流数据很好证明的参数。该模型显示出能够预测第二种湍流情况下溶血的一般行为。结果表明，墙剪在大多数情况下可能起主要作用。

结论

将层流幂律模型推广到湍流的ICTVSS框架显示出了希望，但将从进一步的数值验证和精心设计的实验中受益。