Department of Biomedical Engineering, Azad University of Mashhad, Iran.
Department of Biomedical Engineering, Sahand University of Technology, Iran.
Biomed Phys Eng Express. 2023 Oct 19;9(6). doi: 10.1088/2057-1976/ad0240.
In this study, we investigate the impact of aortic stenosis on the hemodynamics of pulsatile blood flow within a 3D aortic model. Employing a non-Newtonian Casson model with a hematocrit of 45%, our study introduces a preliminary hypothesis to simulate blood flow dynamics, incorporating both linear elastic and viscoelastic models to define the mechanical characteristics of the artery. Through simulations conducted with Ansys-Cfx (version 15), we utilize a 2-way fluid-structure interaction (FSI) approach, employing a Lagrangian-Eulerian formulation with second-order accuracy. We explore the influence of stenosis severity on variables including velocity profiles, pressure distribution, shear stress, wall displacement, and changes in the OSI parameter. Our investigation encompasses arteries with both elastic and viscoelastic walls. The key findings that arise from our results highlight the viscoelastic model's demonstration of reduced radial wall displacement when compared to the linear elastic model. Additionally, we observe that elevated arterial stenosis percentages lead to the elongation of vortex length, heightened wall shear stress, and increased slope of velocity profiles downstream of the stenosed region. Furthermore, bulky obstruction of viscoelastic arteries as opposed to elastic, resulted in a maximum 5 percent increase in velocity profile and a 29.6% decrease in radial displacement. The zenith of shear stress occurs concomitantly with the velocity's peak within the stenosed area. Viscoelastic arterial wall shear stress at the stenosis site escalates due to the rapid expansion of the stenosis. The viscoelastic wall, responding with a blend of viscous and elastic characteristics to applied stress, undergoes slight deformation in shape. Following stress reduction, the wall gradually reverts to its original form, thus alleviating some of the applied stress. In contrast, the elastic wall retains its altered shape due to stress preservation within the material. Additionally, we ascertain an augmentation in radial displacement corresponding with increased artery stenosis.
在这项研究中，我们研究了主动脉瓣狭窄对 3D 主动脉模型内脉动血流流动力学的影响。我们采用血细胞比容为 45%的非牛顿 Casson 模型，提出了一个初步假设来模拟血流动力学，同时纳入线性弹性和粘弹性模型来定义动脉的力学特性。通过使用 Ansys-Cfx（版本 15）进行模拟，我们采用具有二阶精度的拉格朗日-欧拉公式的双向流固耦合（FSI）方法。我们探讨了狭窄严重程度对速度分布、压力分布、壁面剪切应力、壁面位移和 OSI 参数变化等变量的影响。我们的研究涵盖了具有弹性和粘弹性壁的动脉。从结果中得出的主要发现是，与线性弹性模型相比，粘弹性模型显示出径向壁面位移减少。此外，我们观察到，升高的动脉狭窄百分比会导致涡旋长度延长、壁面剪切应力增加以及狭窄区域下游速度分布斜率增加。此外，与弹性动脉相比，粘弹性动脉的大块阻塞导致速度分布增加 5%，径向位移减少 29.6%。剪切应力的峰值与狭窄区域内速度的峰值同时出现。由于狭窄的迅速扩张，狭窄处的粘弹性动脉壁面剪切应力增加。粘弹性动脉壁会因施加的应力而发生轻微的形状变形，这种变形是由粘性和弹性特性共同作用的结果。在应力降低后，壁逐渐恢复到原来的形状，从而减轻了一些施加的应力。相比之下，弹性壁由于材料内部的应力保持而保留其改变后的形状。此外，我们还发现随着动脉狭窄程度的增加，径向位移也会增加。
