Wall Shear Stress Estimation of Thoracic Aortic Aneurysm Using Computational Fluid Dynamics.
Wall Shear Stress Estimation of Thoracic Aortic Aneurysm Using Computational Fluid Dynamics.
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DOI：
10.1155/2018/7126532
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发表时间：
2018
影响因子：
--
通讯作者：
Sudharsan NM
中科院分区：
文献类型：
--
作者：
Febina J;Sikkandar MY;Sudharsan NM
尝试使用计算流体动力学（CFD）评价壁面切应力（WSS）对胸主动脉瘤（TAA）的影响。动脉瘤是由于许多生理因素导致的动脉壁的过度局部肿胀，并且它可能破裂，导致休克或猝死。现有的成像方式，如MRI和CT有助于内脏器官异常的可视化。然而，在压力条件下动脉隆起的预期动态行为只能通过数学建模进行有效评估。在这项工作中，从CT扫描切片重建3D动脉瘤模型，并最终将模型导入星星CCM+（Siemens，USA）进行密集的CFD分析。为了更准确地捕捉弱化边界，采用带棱柱层的多面体网格对区域进行离散。如速度矢量图所示，当TAA中存在流动逆转时，细胞损伤有可能导致凝块。这是由于流型在系统中产生的剪切。从所提出的数学模型中观察到，恶化的WSS是可能破裂的指标，其值在心动周期以及不同的应力条件下振荡。在这个模型中，涡的形成模式和流动逆转也被捕获。非牛顿模型，包括脉动流而不是稳定的平均流，不会过度预测WSS（15.29 Pa，而牛顿模型为16 Pa）。虽然在一个循环中，流动行为是层流-湍流-层流（LTL），但利用非牛顿模型沿着LTL模型也高估了WSS，其值为20.1 Pa。这里提出的数值研究提供了良好的洞察力TAA使用系统的方法进行数值建模和分析。
An attempt has been made to evaluate the effects of wall shear stress (WSS) on thoracic aortic aneurysm (TAA) using Computational Fluid Dynamics (CFD). Aneurysm is an excessive localized swelling of the arterial wall due to many physiological factors and it may rupture causing shock or sudden death. The existing imaging modalities such as MRI and CT assist in the visualization of anomalies in internal organs. However, the expected dynamic behaviour of arterial bulge under stressed condition can only be effectively evaluated through mathematical modelling. In this work, a 3D aneurysm model is reconstructed from the CT scan slices and eventually the model is imported to Star CCM+ (Siemens, USA) for intensive CFD analysis. The domain is discretized using polyhedral mesh with prism layers to capture the weakening boundary more accurately. When there is flow reversal in TAA as seen in the velocity vector plot, there is a chance of cell damage causing clots. This is because of the shear created in the system due to the flow pattern. It is observed from the proposed mathematical modelling that the deteriorating WSS is an indicator for possible rupture and its value oscillates over a cardiac cycle as well as over different stress conditions. In this model, the vortex formation pattern and flow reversals are also captured. The non-Newtonian model, including a pulsatile flow instead of a steady average flow, does not overpredict the WSS (15.29 Pa compared to 16 Pa for the Newtonian model). Although in a cycle the flow behaviour is laminar-turbulent-laminar (LTL), utilizing the non-Newtonian model along with LTL model also overpredicted the WSS with a value of 20.1 Pa. The numerical study presented here provides good insight of TAA using a systematic approach to numerical modelling and analysis.
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