中文摘要：

采用计算流体力学方法分别对6种狭窄率的颈动脉内非Newton瞬态血流进行流固耦合数值分析．研究了狭窄率对颈动脉内血流动力学分布的影响，以探索狭窄率与颈动脉内粥样斑块形成的关系．结果表明，狭窄率不同的颈动脉内血流动力学分布特性明显不同，与0．05。0．1，0．2．0．3和0．4这5种狭窄率的颈动脉内血流动力学分布特性相比，狭窄率为0．5的颈动脉内血流动力学分布独特，狭窄部位附近区域存在面积较大的低速涡流区；复杂血流作用下，该区域分布低壁面压力，异常壁面切应力，较大管壁形变量和vonMises应力；血流速度低使血液中脂质、纤维蛋白等大分子易沉积，低壁面压力引起的明显“负压”效应引发脑部供血障碍，异常壁面切应力作用下粥样斑块易破裂与脱落，并堵塞脑血管，较大的VOllMises应力易引起应力集中，导致血管破裂。为脑卒中发生提供有利条件．因此。狭窄率越大对颈动脉内血流动力学分布的影响越显著．促进颈动脉粥样斑块形成与发展，并引发缺血性脑卒中．

英文摘要：

The non-Newtonian transient blood flow with fluid-structure interaction was numeri- cally simulated for 6 stenosis ratios of carotid arteries with the computational fluid dynamics method. The effects of the carotid artery stenosis ratio on the hemodynamic performance were investigated to clarify the relationship between the stenosis ratio and the atherosclerotic plaque formation and development in the carotid artery. The results show that, different stenosis ratios of the carotid artery result in obviously dissimilar hemodynamic characteristic distributions. Compared with the stenosis ratios of 0.05, 0.1, 0.2, 0.3 and 0.4, the stenosis ratio of 0.5 corre- sponds to strikingly larger blood stagnant vortex flow zones around the stenotic section. Under the action of the complex bood flow field, lower wall pressure, abnormal wall shear stress dis- tribution, larger total mesh displacement and higher von Mises stress will occur around this sec- tion, where the lipid and fibrin macromolecules may easily deposit due to low-speed blood flow. Meanwhile, low wall pressure may cause obvious ＇ negative pressure＇ effects, and in turn insufficient blood supply for brain. Furthermore, the atherosclerotic plaques are liable to rup- ture and fall off under abnormal wall shear stress distribution, and consequently block the blood vessel in brain. Large vascular von Mises stress may cause stress concentration and rup- ture of blood vessel, providing favorable conditions for the occurrence of stroke. Therefore, the larger stenosis ratio the carotid artery has, the greater the influence is on the formation and de- velopment of atherosclerotic plaques, and the higher the possibility of cerebral ischemic stroke Occurs.