Hong Hyeonji, Yeom Eunseop, Ji Ho Seong, Kim Hyun Dong, Kim Kyung Chun
School of Mechanical Engineering, Pusan National University, Busan, South Korea.
MEMS Technology Centre, Pusan National University, Busan, South Korea.
PLoS One. 2017 Oct 19;12(10):e0186300. doi: 10.1371/journal.pone.0186300. eCollection 2017.
Spatial and temporal variations of the hemodynamic features occur under pulsatile conditions in complex vessel geometry. Wall shear stress affected by the disturbed flow can result in endothelial cell dysfunction, which leads to atherogenesis and thrombosis. Therefore, detailed understanding of the hemodynamic characteristics in a curved stenosed channel is highly important when examining the pathological effects of hemodynamic phenomena on the progression of atherosclerosis. The present study measures the velocity fields of pulsatile flows with three different Reynolds numbers in 3D curved vessel models with stenosis using time-resolved particle image velocimetry (PIV). Three different models were cast in PDMS polymer using models made by a 3D printer with different bend angles of 0°, 10°, and 20° between the longitudinal axes at the upstream and downstream of the stenosis. To investigate the 3D flow structures, a stack of 2D velocity fields was obtained by adjusting the position of the laser sheet along the Z-direction. The structures of flow fields in the stenosed models were analyzed using the distribution of the shearing strain as well as the skewness and full width at half maximum of the velocity profile. To support experiment results, distributions of pressure and 3D vortex in the curved stenosed channels were estimated by conducting the numerical simulation. These results indicate that the curvature of the tube considerably influences the skewness of the flow, and the shear stress is intensified near the outer curvature wall due to centrifugal force. The results would be helpful in understanding the effects of geometrical factors on plaque rupture and severe cardiovascular diseases.
在复杂血管几何形状的脉动条件下，血液动力学特征会出现空间和时间上的变化。受紊乱血流影响的壁面剪应力会导致内皮细胞功能障碍，进而引发动脉粥样硬化和血栓形成。因此，在研究血液动力学现象对动脉粥样硬化进展的病理影响时，详细了解弯曲狭窄通道中的血液动力学特征非常重要。本研究使用时间分辨粒子图像测速技术（PIV），测量了具有狭窄的三维弯曲血管模型中三种不同雷诺数的脉动流速度场。使用3D打印机制作的模型在PDMS聚合物中浇铸了三种不同的模型，狭窄上下游纵向轴之间的弯曲角度分别为0°、10°和20°。为了研究三维流动结构，通过沿Z方向调整激光片的位置获得了一系列二维速度场。利用剪切应变的分布以及速度剖面的偏度和半高全宽分析了狭窄模型中的流场结构。为了支持实验结果，通过进行数值模拟估计了弯曲狭窄通道中的压力分布和三维涡旋。这些结果表明，管道的曲率对流动的偏度有很大影响，由于离心力，外曲率壁附近的剪应力会增强。这些结果将有助于理解几何因素对斑块破裂和严重心血管疾病的影响。
