Jodko Daniel, Obidowski Damian, Reorowicz Piotr, Jóźwik Krzysztof
Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland.
Acta Bioeng Biomech. 2016;18(4):3-13.
The aim of this study was to investigate the blood flow in the end-to-side arteriovenous (a-v) fistula, taking into account its pulsating nature and the patient-specific geometry of blood vessels. Computational Fluid Dynamics (CFD) methods were used for this analysis.
DICOM images of the fistula, obtained from the angio-computed tomography, were a source of the data applied to develop a 3D geometrical model of the fistula. The model was meshed, then the ANSYS CFX v. 15.0 code was used to perform simulations of the flow in the vessels under analysis. Mesh independence tests were conducted. The non-Newtonian rheological model of blood and the Shear Stress Transport model of turbulence were employed. Blood vessel walls were assumed to be rigid.
Flow patterns, velocity fields, the volume flow rate, the wall shear stress (WSS) propagation on particular blood vessel walls were shown versus time. The maximal value of the blood velocity was identified in the anastomosis - the place where the artery is connected to the vein. The flow rate was calculated for all veins receiving blood.
The blood flow in the geometrically complicated a-v fistula was simulated. The values and oscillations of the WSS are the largest in the anastomosis, much lower in the artery and the lowest in the cephalic vein. A strong influence of the mesh on the results concerning the maximal and area-averaged WSS was shown. The relation between simulations of the pulsating and stationary flow under time-averaged flow conditions was presented.
本研究旨在研究端侧动静脉内瘘的血流情况，同时考虑其脉动特性以及血管的个体特异性几何形状。采用计算流体动力学（CFD）方法进行此分析。
从血管计算机断层扫描获得的内瘘DICOM图像是用于构建内瘘三维几何模型的数据来源。对模型进行网格划分，然后使用ANSYS CFX v. 15.0代码对所分析血管内的血流进行模拟。进行了网格独立性测试。采用血液的非牛顿流变模型和湍流的剪切应力输运模型。假定血管壁为刚性。
展示了血流模式、速度场、体积流量以及特定血管壁上壁面剪切应力（WSS）随时间的传播情况。在吻合口（动脉与静脉相连处）确定了血流速度的最大值。计算了所有接受血液的静脉的流量。
模拟了几何形状复杂的动静脉内瘘中的血流。吻合口中WSS的值和振荡最大，动脉中较低，头静脉中最低。显示了网格对最大和面积平均WSS结果的强烈影响。给出了时间平均流动条件下脉动流和稳态流模拟之间的关系。
