School of Biological Science & Medical Engineering, Beihang University, Beijing, 100191, China.
Ann Biomed Eng. 2010 Mar;38(3):917-26. doi: 10.1007/s10439-009-9878-8. Epub 2009 Dec 24.
To test the hypothesis that the spiral flow pattern in the human aorta may play a beneficial role in the transport of oxygen, hence sparing the ascending aorta from atherosclerosis, a comparative study on the distribution of oxygen flux to the arterial wall was carried out numerically for three aorta models. The first one (Model 1) was constructed based on MRI images of a human aorta acquired in vivo. The second (Model 2) was made the same as Model 1 but without the three branches. The third (Model 3) was similar to Model 2 only with the aortic torsion removed. The results showed that without the torsion, the flow fashion in Model 3 was very different from the swirling flows in Models 1 and 2 and exhibited the typical characteristics of Dean flow with two symmetrical helical structures. In Models 1 and 2, the average Sherwood number (Sh) in the ascending aorta with the presence of a strong spiral flow was not only higher than that in the inner wall of the descending aorta where the spiral flow faded out, but also generally higher than that in Model 3. The comparison between Models 2 and 3 demonstrated that the averaged Sh from ascending aorta to aortic arch was relatively higher for Model 2. In conclusion, the spiral or swirling flow may have certain physiological significance in the aorta and play a positive role in the transport of oxygen by enhancing oxygen flux to the arterial wall.
为了验证人类主动脉中的螺旋流动模式可能在氧气输送中发挥有益作用,从而使升主动脉免受动脉粥样硬化的影响,我们对三种主动脉模型的动脉壁氧气通量分布进行了数值比较研究。第一个模型(模型 1)是基于人体主动脉的 MRI 图像构建的。第二个(模型 2)与模型 1 相同,但没有三个分支。第三个(模型 3)与模型 2 相似,只是没有扭转。结果表明,没有扭转,模型 3 中的流动方式与模型 1 和 2 中的螺旋流非常不同,表现出典型的双对称螺旋结构的 Dean 流特征。在模型 1 和 2 中,具有强螺旋流的升主动脉的平均 Sherwood 数(Sh)不仅高于螺旋流逐渐消失的降主动脉内壁的 Sh,而且通常高于模型 3 的 Sh。模型 2 和 3 的比较表明,对于模型 2,从升主动脉到主动脉弓的平均 Sh 相对较高。总之,螺旋或漩涡流动在主动脉中可能具有一定的生理意义,通过增强氧气向动脉壁的输送,对氧气的输送起到积极的作用。