A COMPUTATIONAL STUDY OF PULSATILE FLOW IN A STENOSIS IN RELATION TO BLOOD DAMA

狭窄处脉动血流与血 DAMA 的计算研究

• 批准号: 8171753
• 负责人: KEEFE B MANNING
• 金额: $ 0.11万
• 依托单位: CARNEGIE-MELLON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8171753
• 关键词: Blood; Blood Vessels; Caliber; Characteristics; Computational Technique; Computer Retrieval of Information on Scientific Projects Database; Data; Funding; Goals; Grant; Institution; Laser-Doppler Velocimetry; Liquid substance; Measures; Minor; Modeling; Pattern; Pharyngeal structure; Pulsatile Flow; Research; Research Personnel; Resources; Source; Stenosis; Stress; Techniques; Thrombus; United States National Institutes of Health; Variant; Work; computer studies; iliac artery; insight; shear stress; simulation

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this work is to study pulsatile flow in a sudden expansion which represents a modeled stenosis which is an abnormal narrowing in a blood vessel . The sudden expansion is used to obtain adverse flow patterns, such as separation, reattachment and eddy formation, that are likely to be seen in stenoses. Computational fluid dynamic (CFD) simulations will be used to obtain velocity and turbulent characteristics of the flow through the sudden expansion at a mean throat Reynolds number of 2000, a peak throat Reynolds number of 4600 and a mean flow rate of 1.25 l/min, which is representative of the flow seen in the iliac artery. The iliac artery is elliptical in cross section with a major axis of 1.53 cm and minor axis of 1.3 cm at the aortic bifurcation, and hence the inlet diameter of our model, which is 12 mm, is representative of the mean diameter of the iliac artery. The variation of the throat Reynolds number from a low of 400 to a high of 4600 will produce flow than transitions from laminar to turbulent. The CFD results of the flow will be compared against the velocity and turbulence characteristics obtained using a three-component laser Doppler velocimetry experimental technique. While previous studies of pulsatile flow in stenoses have only been conducted using one-component LDV, this study uses three-component LDV which enables us to simultaneously capture all three components of flow, and hence allows us to compute turbulence data that is more accurate. Also, previous studies of pulsatile flow in stenoses using computational techniques have relied on direct numerical simulation (DNS) techniques to produce accurate representations of the flow. We will use a less computationally expensive implicit large eddy (ILES) technique to predict the flow in the sudden expansion and intend to show that the ILES simulation results match the experimental results just as accurately as DNS. The threshold level of turbulent shear stress responsible for blood damage in a submerged jet was found to be 4000 by other researchers. We will correlate the levels of blood damage that may occur in pulsatile stenotic flows by comparing the turbulent stress measured in the sudden expansion to this threshold level. We hypothesize that the mean turbulent shear stress in the flow will be low compared to steady flow at similar Reynolds numbers. However, the instantaneous values of turbulent shear stress may be much larger, resulting in higher levels of blood damage. This work may provide valuable insights to researchers to better predict the stresses seen in pulsatile stenotic flows and their implications to blood damage and thrombus formation.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 这项工作的目的是在突然的膨胀中研究脉冲流，这代表了建模的狭窄，这是血管中异常狭窄的狭窄。突然的膨胀用于获得不良流动模式，例如分离，重新介绍和涡流形成，可能会在狭窄中看到。计算流体动力学（CFD）模拟将用于在平均喉咙雷诺数2000的突然膨胀中获得流动的速度和湍流特性，喉咙雷诺数为4600，平均流量为4600，平均流速为1.25 l/min，这代表了伊利亚克（Iliac）的流动。在主动脉分叉时，叶状动脉在横截面上是椭圆形的，其主要轴为1.53 cm，次要轴为1.3 cm，因此我们模型的入口直径为12 mm，代表了伊利亚克动脉的平均直径。喉咙雷诺数从400的低点到高4600的变化将比从层流到湍流的过渡产生流动。将与使用三组分激光多普勒速度计实验技术获得的速度和湍流特性进行比较。虽然先前仅使用一组分LDV进行了对伸卵的脉动流动的研究，但本研究使用了三组分LDV，使我们能够同时捕获所有三个流量的流量，因此使我们能够计算更准确的湍流数据。此外，先前使用计算技术对降低性脉动流动的研究依赖于直接数值模拟（DNS）技术来产生流量的准确表示。我们将使用较不昂贵的隐式大涡流（Iles）技术来预测突然膨胀中的流量，并打算表明Iles Simulation结果与DNS一样准确地匹配了实验结果。其他研究人员发现，淹没喷气机中负责血液损伤的湍流剪切应力的阈值水平是4000。我们将通过比较在突然的扩张中测量到该阈值水平的湍流应力，将脉冲狭窄流中可能发生的血液损伤水平相关联。我们假设与相似的雷诺数下的稳定流量相比，流动中的平均湍流剪切应力将很低。但是，湍流剪切应力的瞬时值可能会更大，从而导致更高的血液损伤。这项工作可以为研究人员提供宝贵的见解，以更好地预测脉动狭窄流中看到的压力及其对血液损伤和血栓形成的影响。