Xue H, Fung Y C
Department of AMES-Bioengineering, University of California, San Diego, La Jolla 92093.
J Biomech Eng. 1989 Feb;111(1):37-41. doi: 10.1115/1.3168337.
In an experiment motivated by the study of arterial blood flow along the lines suggested by the traditional Chinese medicine, the flow in a pipe whose lumen was blocked by a semi-circular plug two tube-diameters long was visualized by suspended particles, recorded by cinematography, and analyzed digitally. The Reynolds number was in the range of 100 to 450 based on the pipe diameter, similar to that of blood flow in the radial artery in the arms of man. The blockage was found to have a profound effect on the velocity profile of the flow in the wake, but it had little influence on the symmetry of the velocity profile upstream of the block, except in its immediate neighborhood. When the end conditions far away from the block were steady, the flow in the wake was steady. The asymmetry of the flow in the wake can be judged by the deviation of the location of the maximum axial velocity from the center line of the pipe as seen in the plane of symmetry of the blockage. Our results show that the deviation can be described as the sum of two components. The first is a strong one which decays exponentially in an entry length which is about twice as long as the classical Boussinesq entry length of axisymmetric flow. The second is a weaker component which is wavy spatially and persists far downstream (many times the entry length). The separated flow and vortex system behind the blockage are sensitive to the flow rate.(ABSTRACT TRUNCATED AT 250 WORDS)
在一项受中医所建议思路启发的关于动脉血流研究的实验中，对一根管腔内被一个两管径长的半圆形塞子阻塞的管道内的流动，通过悬浮粒子使其可视化，用电影摄影记录并进行数字分析。基于管道直径，雷诺数在100至450范围内，类似于人体手臂桡动脉中的血流情况。发现该阻塞对尾流中流动的速度剖面有深远影响，但对阻塞上游速度剖面的对称性影响很小，除了在其紧邻区域。当远离阻塞的端部条件稳定时，尾流中的流动是稳定的。尾流中流动的不对称性可通过在阻塞对称平面中观察到的最大轴向速度位置相对于管道中心线的偏差来判断。我们的结果表明，该偏差可描述为两个分量之和。第一个分量很强，在一个入口长度内呈指数衰减，该入口长度约为轴对称流动经典布辛涅斯克入口长度的两倍。第二个分量较弱，在空间上呈波浪状且在下游很远的地方（入口长度的许多倍）仍然存在。阻塞后面的分离流和涡旋系统对流速很敏感。（摘要截于250字）
