1.4.3　局部狭窄血管低密度脂蛋白浓度分布的数值模拟

数值模拟结果表明由于透过动脉管壁渗流的存在，LDL将在狭窄远心端血管壁内表面积聚，在狭窄血管远心端形成一浓度急剧增加的区域，并且存在一LDL峰值，该峰值随入口流速的增加而减少，并且随着狭窄程度的增加该变化更为明显。但在入口流速一定的情况下，该峰值随狭窄程度的改变而改变，在Re为250时，40%狭窄血管远心端LDL浓度峰值为本体浓度的153%，高于30%狭窄（129%）以及50%狭窄（141%）（图1-16）。

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图1-15　血管狭窄区域的流场分析。（a）局部狭窄动脉的几何模型。狭窄血管段为轴对称管。狭窄血管段半径 r=0.075 cm，平直血管段直径R=0.125 cm。（R- r）/R表示狭窄的程度（40%），L1=5 cm 和L2=0.8 cm。（b）狭窄血管的三维模型和网格划分。（c）粒子图像测速技术（PIV）系统示意图。数值模拟（d）和PIV测定（e）确定血管狭窄区域中流场的分布。［引自：Xie X, et al. In vitro and in vivo investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish［J］. J R Soc Interface, 2013, 10（82）: 20121053.］
Figure 1-15　Flow field analysis of local stenotic artery. （a）The geometric model of the local stenotic artery. The stenotic vessels were axisymmetric. The radius of the stenotic part r was 0.075 cm, and the diameter of the straight part R was 0.125 cm. （R-r）/R is the degree of stenosis （40%）, L1=5 cm and L2=0.8 cm. （b）Three dimensional model and mesh generation of stenotic vessels. （c）Particle image velocimetry （PIV） system schematic diagram.The distribution of flow field in the stenosis area was determined by simulation （d） and PIV measurement （e）. ［Adapted from: Xie X, et al. In vitro and in vivo investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish［J］. J R Soc Interface, 2013, 10（82）: 20121053.］