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Fluid structure interaction study in model abdominal aortic aneurysms: Influence of shape and wall motion
International Journal for Numerical Methods in Biomedical Engineering ( IF 2.2 ) Pub Date : 2020-12-07 , DOI: 10.1002/cnm.3426 Nimmy Thankom Philip 1 , B. S. V. Patnaik 1 , Sudhir B. J. 2
International Journal for Numerical Methods in Biomedical Engineering ( IF 2.2 ) Pub Date : 2020-12-07 , DOI: 10.1002/cnm.3426 Nimmy Thankom Philip 1 , B. S. V. Patnaik 1 , Sudhir B. J. 2
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Aneurysms are bulges in arteries which reflect unhealthy state of conduit in which blood is flowing. In the aorta, they are typically found in the abdominal region as well as thoracic region. Understanding the rupture risk of these vessels is critical to preventing failure and fatalities. In the current clinical practice, treatment modalities are initiated, when the out‐pouching exceeds maximum diameter (Dmax). However this approach is very crude as it does not account for the fluid mechanical forces and the attendant stresses. Since it is medically and ethically not possible to follow the patients to study the rupture risk potential, fluid structure interaction (FSI) modelling would be an apt tool to develop adequate understanding on various hemodynamic parameters. On the other hand, performing patient‐specific studies would demand adequate lead time and they are computationally expensive as well. In the present study, the shape of the aneurysm and its interaction with the flowing fluid are accounted through the shape indices to study the FSI effects on the hemodynamic parameters. Numerical simulation of Newtonian flow through five axi‐symmetric geometries with different shape indices coupled with a linear elastic vessel wall model is considered. From these simulations, it was observed that (Dmax) to height ratio (DHr) is the most significant shape index which influences the variation of all hemodynamic parameters, which makes it a potential candidate for predicting rupture risk. Wall acceleration due to pulsatile flow was found to cause the onset of re‐circulation zones at the centre of the aneurysm during early systole and the temporal deceleration resulted in the generation of near wall eddying structures during late diastole. Investigation of turbulence carried out with k‐ω Shear Stress transport turbulence model, predicts a turbulence intensity of greater than 1.5% in the diseased segment as well as the distal end of the aneurysm.
中文翻译：
模型腹主动脉瘤中流体结构相互作用的研究：形状和壁运动的影响
动脉瘤是动脉中的凸起，反映了血液在其中流动的导管的不健康状态。在主动脉中，它们通常在腹部区域和胸部区域被发现。了解这些血管的破裂风险对于防止故障和死亡至关重要。在当前的临床实践中，当外包装超出最大直径（D max）。但是，这种方法非常粗糙，因为它不能解决流体机械力和随之而来的应力。由于在医学和伦理上不可能跟随患者来研究潜在的破裂风险，因此流体结构相互作用（FSI）建模将是一种适当的工具，可以对各种血液动力学参数进行充分的了解。另一方面，进行针对患者的研究需要足够的交付时间，并且在计算上也很昂贵。在本研究中，通过形状指数考虑动脉瘤的形状及其与流动流体的相互作用，以研究FSI对血液动力学参数的影响。考虑了牛顿流通过具有不同形状指数的五个轴对称几何形状的数值模拟，并结合了线性弹性容器壁模型。D max）与身高之比（DHr）是影响所有血液动力学参数变化的最重要的形状指标，这使其成为预测破裂风险的潜在候选者。发现由于脉动血流引起的壁加速在早期收缩期间引起动脉瘤中心的再循环区域的发作，并且时间的减速导致在舒张晚期期间产生近壁涡流结构。用k- ω剪切应力传递湍流模型进行的湍流研究表明，患病段以及动脉瘤远端的湍流强度大于1.5％。
更新日期：2020-12-07
中文翻译：
模型腹主动脉瘤中流体结构相互作用的研究：形状和壁运动的影响
动脉瘤是动脉中的凸起，反映了血液在其中流动的导管的不健康状态。在主动脉中，它们通常在腹部区域和胸部区域被发现。了解这些血管的破裂风险对于防止故障和死亡至关重要。在当前的临床实践中，当外包装超出最大直径（D max）。但是，这种方法非常粗糙，因为它不能解决流体机械力和随之而来的应力。由于在医学和伦理上不可能跟随患者来研究潜在的破裂风险，因此流体结构相互作用（FSI）建模将是一种适当的工具，可以对各种血液动力学参数进行充分的了解。另一方面，进行针对患者的研究需要足够的交付时间，并且在计算上也很昂贵。在本研究中，通过形状指数考虑动脉瘤的形状及其与流动流体的相互作用，以研究FSI对血液动力学参数的影响。考虑了牛顿流通过具有不同形状指数的五个轴对称几何形状的数值模拟，并结合了线性弹性容器壁模型。D max）与身高之比（DHr）是影响所有血液动力学参数变化的最重要的形状指标，这使其成为预测破裂风险的潜在候选者。发现由于脉动血流引起的壁加速在早期收缩期间引起动脉瘤中心的再循环区域的发作，并且时间的减速导致在舒张晚期期间产生近壁涡流结构。用k- ω剪切应力传递湍流模型进行的湍流研究表明，患病段以及动脉瘤远端的湍流强度大于1.5％。
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