Yi Hang, Yang Zifeng, Johnson Mark, Bramlage Luke, Ludwig Bryan
Department of Mechanical and Material Engineering, Wright State University, 3640 Colonel Glenn Hwy., Dayton, Ohio 45435, USA.
Boonshoft School of Medicine, Wright State University, Dayton, Ohio 45435, USA.
Phys Fluids (1994). 2022 Oct;34(10):103101. doi: 10.1063/5.0118097. Epub 2022 Oct 3.
This study aims to develop an experimentally validated computational fluid dynamics (CFD) model to estimate hemodynamic characteristics in cerebral aneurysms (CAs) using non-Newtonian blood analogues. Blood viscosities varying with shear rates were measured under four temperatures first, which serves as the reference for the generation of blood analogues. Using the blood analogue, particle image velocimetry (PIV) measurements were conducted to quantify flow characteristics in a CA model. Then, using the identical blood properties in the experiment, CFD simulations were executed to quantify the flow patterns, which were used to compare with the PIV counterpart. Additionally, hemodynamic characteristics in the simplified Newtonian and non-Newtonian models were quantified and compared using the experimentally validated CFD model. Results showed the proposed non-Newtonian viscosity model can predict blood shear-thinning properties accurately under varying temperatures and shear rates. Another developed viscosity model based on the blood analogue can well represent blood rheological properties. The comparisons in flow characteristics show good agreements between PIV and CFD, demonstrating the developed CFD model is qualified to investigate hemodynamic factors within CAs. Furthermore, results show the differences of absolute values were insignificant between Newtonian and non-Newtonian fluids in the distributions of wall shear stress (WSS) and oscillatory shear index (OSI) on arterial walls. However, not only does the simplified Newtonian model underestimate WSS and OSI in most regions of the aneurysmal sac, but it also makes mistakes in identifying the high OSI regions on the sac surface, which may mislead the hemodynamic assessment on the pathophysiology of CAs.
本研究旨在开发一个经过实验验证的计算流体动力学（CFD）模型，以使用非牛顿血液模拟物来估计脑动脉瘤（CA）中的血流动力学特征。首先在四个温度下测量了随剪切率变化的血液粘度，这为生成血液模拟物提供了参考。使用血液模拟物，进行了粒子图像测速（PIV）测量以量化CA模型中的流动特性。然后，在实验中使用相同的血液特性，执行CFD模拟以量化流动模式，并将其与PIV测量结果进行比较。此外，使用经过实验验证的CFD模型对简化的牛顿模型和非牛顿模型中的血流动力学特征进行了量化和比较。结果表明，所提出的非牛顿粘度模型能够在不同温度和剪切率下准确预测血液的剪切变稀特性。另一个基于血液模拟物开发的粘度模型能够很好地代表血液流变特性。流动特性的比较表明PIV和CFD之间具有良好的一致性，这表明所开发的CFD模型有资格研究CA内的血流动力学因素。此外，结果表明，在动脉壁上的壁面剪切应力（WSS）和振荡剪切指数（OSI）分布中，牛顿流体和非牛顿流体的绝对值差异不显著。然而，简化的牛顿模型不仅在动脉瘤囊的大多数区域低估了WSS和OSI，而且在识别囊表面的高OSI区域时也出现了错误，这可能会误导对CA病理生理学的血流动力学评估。
