肺动脉及其分支血液动力学的数值模拟研究

发布时间：2018-07-16 13:38

【摘要】：本文对牛顿特性血液流体、非牛顿特性血液流体在人体肺动脉及其分支内的血流动力学特性进行了数值模拟,并使用有限元方法对血液与血管的流固耦合问题进行了模拟研究。本文首先建立90°弯管模型,假定血液为牛顿流体,对弯管内血液动力学环境进行数值模拟,并将模拟结果与实验数据进行对比,发现两者具有较好的吻合性,证明拟采用的数值方法能够比较真实的模拟血管内血液的流动情况。进而采用Womersley脉动速度入口条件,对重建后的肺动脉及其分支,在一个心动周期内的牛顿脉动流血流动力学环境进行了数值模拟研究。然后,同样建立90°弯管模型对非牛顿特性血液流进行数值模拟,验证数值方法的适用性。考虑血液的非牛顿特性,将carreau模型应用到控制方程中,求解了肺动脉及其分支的血液动力学参数。研究表明,正常成人在心脏收缩期,主肺动脉及左、右肺动脉分支的压力均较心脏舒张期高；右肺动脉压力明显高于左肺动脉,右叶间动脉压力较左侧高；主肺动脉及左、右肺动脉内的流速有显著性差异,右肺动脉远端流速远大于左肺动脉；在收缩期右肺动脉分叉前近端血流形成高壁面剪切力场。由此可见,右肺动脉近端和右叶间动脉是血液动力学参数最早出现改变的阶段,对于早期肺动脉高压的诊断,应着眼于此段动脉的形态及功能改变。另外,本文将牛顿特性血液流体与非牛顿特性血液流体数值模拟结果进行对比,结果显示,牛顿流体与非牛顿流体模拟结果数值上存在差异,但动脉内速度、压力以及壁面剪切力分布的轮廓基本一致。最后,建立基于真实人体肺动脉的三维分叉结构,研究血液与弹性壁流固耦合问题,对血管的变形情况、血流的动力学特性进行了数值模拟。结果显示,在等效应力最大处,变形也最大,符合生理规律。肺动脉出入口以及分叉处是整个心动周期内流速、压力以及壁面剪切力变化最活跃的位置,也是整个心动周期内压力、流速和最高剪切力出现的位置,所以肺动脉出入口,以及分叉处是发生病变的最初位置。
[Abstract]:In this paper, the hemodynamic characteristics of Newtonian blood fluid and non-Newtonian blood fluid in human pulmonary artery and its branches are numerically simulated, and the fluid-solid coupling between blood and blood vessel is studied by finite element method. In this paper, a 90 掳curved pipe model is established. The hemodynamic environment in the bend is numerically simulated on the assumption that the blood is Newtonian fluid, and the simulation results are compared with the experimental data. It is found that the two models are in good agreement with each other. It is proved that the proposed numerical method can simulate the flow of blood in blood vessels. Then the dynamic environment of Newtonian pulsating blood flow in a cardiac cycle was numerically simulated by using the Womersley pulsation velocity inlet condition for the reconstructed pulmonary artery and its branches. Then, the 90 掳bend model is also established to simulate the non-Newtonian characteristic blood flow, which verifies the applicability of the numerical method. Considering the non-Newtonian characteristics of blood, the carreau model is applied to the governing equation, and the hemodynamic parameters of the pulmonary artery and its branches are solved. Studies have shown that the pressure of the main pulmonary artery and the branches of the left and right pulmonary arteries in normal adults is higher than that in the diastolic period, the pressure of the right pulmonary artery is significantly higher than that of the left pulmonary artery, the pressure of the right interlobar artery is higher than that of the left, the pressure of the main pulmonary artery and the left pulmonary artery, The velocity in the right pulmonary artery was significantly different, the velocity of the distal right pulmonary artery was much larger than that of the left pulmonary artery, and a high wall shear force field was formed at the proximal end of the right pulmonary artery bifurcation in the systolic phase. It can be seen that the proximal right pulmonary artery and the right interlobar artery are the earliest changes in hemodynamic parameters. For the diagnosis of early pulmonary hypertension, we should focus on the morphological and functional changes of this segment of artery. In addition, the numerical simulation results of Newtonian blood fluid and non-Newtonian blood fluid are compared. The results show that the numerical value of Newtonian fluid and non-Newtonian fluid is different, but the velocity of artery is different. The profile of pressure and wall shear force distribution is basically the same. Finally, a three-dimensional bifurcation structure based on real human pulmonary artery is established to study the fluid-solid coupling between blood and elastic wall. The deformation of blood vessels and the dynamic characteristics of blood flow are numerically simulated. The results show that the deformation is the largest at the maximum equivalent stress, which accords with the physiological law. The entrance and exit of the pulmonary artery and the bifurcation are the most active sites for the changes of velocity, pressure and wall shear force throughout the cardiac cycle, and also the location where the pressure, velocity and maximum shear force appear throughout the cardiac cycle, so the pulmonary artery entrance and exit. And the bifurcation is the initial location of the lesion.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：R312

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