An off-lattice Boltzmann method for blood flow simulation through a model irregular arterial stenosis: The effects of amplitude and frequency of the irregularity
An off-lattice Boltzmann method for blood flow simulation through a model irregular arterial stenosis: The effects of amplitude and frequency of the irregularity
复制标题
通过不规则动脉狭窄模型进行血流模拟的离格玻尔兹曼方法：不规则幅度和频率的影响
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
K. Anupindi
中科院分区：
文献类型：
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作者：
M. Sakthivel;K. Anupindi
在这项工作中，开发了一个基于有限差分的轴对称非格子Boltzmann求解器来模拟病变动脉中的血液流动。所提出的解算器使用贴体曲线网格处理动脉几何形状。流动的轴对称性质和血液的非牛顿行为使用外部源项合并。使用文献中的参考数据，该解算器被验证为可以通过腹主动脉瘤在空间上发展脉动性血流。然后，系统地研究了不规则形状狭窄动脉的振幅和频率的影响。利用瞬时涡量等值线、流线、周期平均和相平均壁面剪切应力(WSS)剖面以及振荡剪切指数对结果进行了分析。此外，研究了低密度脂蛋白的管腔表面浓度(LSC)和WSS之间的相关性，以预测潜在的疾病起始和进展位置。值得注意的是，狭窄不规则性幅度的增加增加了WSS剖面的最大值和最小值的幅度，而不改变它们的位置。另一方面，不规则性频率的增加增加了WSS极值的幅度，同时使峰值更接近。此外，在不规则程度和LSC升高的位置数目之间也发现了正相关。不规则性的存在会在狭窄的上游部分产生额外的漩涡。狭窄的上下游段都受到相对较大的剪切层的影响，这可能导致内皮细胞的损伤。最后，用幂函数模型研究了血液的剪切变稀效应。与牛顿模型相比，剪切变薄模型中WSS的极大值和极小值的大小较小。此外，由于不规则性在上游段产生的漩涡也会被血液的剪切稀化效应所抑制。
In this work, a finite-difference-based axisymmetric off-lattice Boltzmann solver is developed to simulate blood flow through pathological arteries. The proposed solver handles arterial geometries using a body-fitted curvilinear mesh. The axisymmetric nature of the flow and the non-Newtonian behavior of blood are incorporated using external source terms. The solver is verified for spatially developing pulsatile inflow through an abdominal aortic aneurysm using reference data from literature. Thereafter, the effects of amplitude and frequency of an irregular-shaped stenosed artery are systematically studied. The results are analyzed using the instantaneous vorticity contours, streamlines, cycle-averaged and phase-averaged profiles of wall shear stress (WSS), and oscillatory shear index. Further, the correlation between the luminal surface concentration (LSC) of low-density lipoproteins and the WSS is studied to predict potential disease initiation and progression locations. It is noted that an increase in the amplitude of irregularity of the stenosis increases the magnitudes of maxima and minima of WSS profiles without altering their locations. On the other hand, an increase in the frequency of irregularity increases the magnitudes of WSS extrema while bringing the peaks closer together. Further, a positive correlation is found between the degree of irregularity as well as the number of locations of elevated LSC. The presence of irregularity creates additional vortices in the upstream section of the stenosis. Both the upstream and downstream sections of the stenosis are subjected to the opposing shear-layers with higher magnitudes, which may lead to endothelial damage. Finally, the shear-thinning effect of blood is studied using the power-law model. The magnitudes of the maxima and minima in WSS have a lower value for the shear-thinning model than the Newtonian case. Also, the vortices that were produced in the upstream section because of the irregularity get suppressed by the shear-thinning effect of the blood.