弹性直圆管局部狭窄对脉动流影响的数值模拟

Nnumerical Simulation of Influence on Pulsatile Flow due to Local Stenosis of an Elastic Cylindrical Tube

动脉中脉搏波的分析和中医脉象研究早为人们注目,并越来越受到重视。中医切脉或利用脉象仪测脉,均沿腕部桡动脉处取得信息,由于手指和探头作用,桡动脉形成狭窄从而影响脉动流。本文建立局部狭窄直圆管内脉动流模型,来研究狭窄对脉动流的影响。根据流动的一维非线性方程导出特征方程,采用特征差分方法数值求解。结果表明:(1)随狭窄度增加(相当压迫加重),压力和速度波形变陡,峰值开始时提高,随后下降,和脉象仪取脉情况吻合;(2)血液粘度增加时,速度减慢,压力波形平坦,反映了血流阻力的增大;(3)狭窄宽度的变化对脉搏波影响不大;(4)根据中医脉图若干指标计算得到的数据,随狭窄和血液粘度的变化,和临床结果一致,说明这几个指标是符合血流动力学规律的。

Radial artery is one of the most typical human surface arteries. A lot of physiological information can be obtained from pulse wave through radial artery. Pulse diagnosis is the clinical diagnosis of traditional chinese medicine. Analysis of pulse wave through artery and pulse research of traditional chinese medicine have been paid much attention to for years. While chinese medicine and pulse-diagrammeter measure pulse wave, the radial artery forms local stenosis which shall affect the pulse wave. Many research works on the pulse diagram of traditional chinese medicine have been reported but the study of the influence due to stenosis of radial artery on pulse wave has not been done so far. In this paper a model of pulsatile flow in cylindrical tube with stenosis is established to study the influence of stenosis on pulse wave. From the one dimensional nonlinear equations the characteristic equations are derived. The characteristic-difference method is adopted to solve these equations numerically. It is shown that:(1) as the stenosis increase, the pressure and velocity waves become sharper, the peak values increase initially and decrease later. It is in agreement with practical measurement using pulse-diagrammeter;(2) as the blood viscosity increases, the flow velocities decrease and pressure wave become mild, showing blood flow resistance increased;03) variations of stenosis width have little ef fection on pulse wave;(4) variation tendency, as the stenosis and blood viscosity vary, of the values calculated according to the clinical pulse diagram indexes of traditional chinese medicine is in accord with clinical results, so these pulse diagram indexes are in agreement with heomodynamics.