心血管内流场的高质量模拟实验研究（Ⅱ）——动态流体双折射实验技术…

本文重点介绍用于心血管内流场的高质量模拟的动态流体双折射实验技术和系统。首先制备了两种仿血双折射液和一种弹性透明的硅橡胶模拟血管，有关参数测定表明它们适用于模拟血流和血管。其次，为了消除光线穿过圆管产生的图象畸变，用光线追迹法推导出消畸方程并选用最佳匹配浸渍液消畸。最终设计建立了一台由微机控制的集流动、光学、图象与数据采集处理和同步控制子系统于一体的新型测量系统。     

心血管内流场的高质量模拟实验研究（Ⅲ）：动态流体双折射法典型应用分析

用动态流体双折射法对三种有代表性的心血管模型（模拟大血管、动脉狭窄和人造心脏瓣膜）中的脉动血流间隙测试，得出速度剖面，剪应力分布，压力和流量之间的相位关系。结果说明本文所描述的双折射液和模拟血管是适用于心血管内流场的高质量模拟实验的，动态流体双折射方法及简化的光－力学关系是适用于低频脉动模拟血流的定量分析的。     

颗粒附壁燃烧机理及模拟方法探讨

在燃用固体燃料，如生物质、煤、固体废弃物时，都存在一定程度的附壁燃烧现象，以燃煤液排渣燃烧器为例，探讨了颗粒在熔融面上的沉积、流动以及燃烧机理。并针对现有煤粉燃烧程序在液排渣燃烧器模拟上的局限，开发了一种考虑液渣流动的附壁燃烧模型，给出了总体的计算框架．通过对不同壁面处理方式下计算结果的比较，分析了不同手法的优劣和特点，为液排渣燃烧器的正确模拟提供一种完整的思路，对生物质或固体废弃物燃烧模拟起到一定的参考作用。     

一种散光图象双折射相移的方法

由Pindera等提出了等达因法导出了平面问题的三个应力分量，可以非破坏性测取受力物体内部的应力状态，是一种有效的光测技术，应力分量与等达因条纹级次的导数相关，为得到具有高测试精度的应力分量在等达因条纹测试中引入了双折射相移技术，文中提出了一种在散光激光入射光路中用加入一可调偏振片和一可调1／4波片实现散光图象双折射相移的方法，该方法设备简单，能保证总体光强的一致性。     

流动双折射实验

流动双折射实验周建和，周兴华，张海荣（天津大学力学系天津３０００７２）流动双折射法，是流动显示中的一种光学方法，主要用于显示低雷诺数下的剪切流动。它能形象直观地显示流场中切应力的分布和切应力的方向。通过对干涉条纹的分析处理，可对流场实现定量测量。尤其...     

流动双折射实验

流动双折射实验周建和，周兴华，张海荣（天津大学力学系天津３０００７２）流动双折射法，是流动显示中的一种光学方法，主要用于显示低雷诺数下的剪切流动。它能形象直观地显示流场中切应力的分布和切应力的方向。通过对干涉条纹的分析处理，可对流场实现定量测量。尤其...     

液滴撞击固体表面时的流体动力特性实验研究

采用高速摄影机及胶片图象分析，系统研究了水滴撞击光滑固体平表面及锯齿状固体表面时的流体动力特性，试验结果表明，水滴撞击表面时的流体动力过程可分为相互力学作用及压缩波传播和流体散流和破裂两个阶段，水滴撞击锯齿状表面时与撞击平表面的流体动力现象有较大差别。     

双折射材料初应力的定量研究相移等达因技术的应用

文章提出两种用相移等达因技术对存在于双折射材料内部的初始应力进行定量分析的方法，并以两种常用的双折射材料Ｐ６和Ｈｏｍａｌｉｔｅ１００为例进行了内部初应力的实验研究，给出了材料内部初应力的分布。以上研究说明双折射内部初始应力不容忽视，数字相移等达因技术是双折射材料内部初始应力进行定量分析的有力手段     

电流变阻尼器的动态特性实验研究

设计制造了一种多层滑动极板式电流变阻尼器，使用自制的电流变液，采用正弦激励，进行了这种电流变阻尼器的阻尼特性试验。研究了电流变阻尼器的载荷－位移迟滞特性和载荷－速率迟滞特性，同时研究分析了这种电流变阻尼器的周期能耗特性及等效粘性阻尼特性。结果表明，阻尼器的周期能耗量随外加电场强度的增加而增加，外加电场强度越大，阻尼器的等效阻尼系数越大。阻尼器的阻尼特性体现为库仑阻尼和粘性阻尼的组合，其中随外加电场强度可控的主要是库仑阻尼力，而且库仑阻尼力不仅与外加强度有关，也与阻尼器的运动速度有关。该阻尼器系统是一个强非线性系统，极板间电流变液在低剪切应变率时表现为Bingham塑性流体，在高剪切应变率时流变性态比较复杂，导致载荷－速率迟滞环出现多区域闭合现象。     

心血管内流场的高质量模拟实验研究（Ⅰ）──动态流体双折射测试原理与分析方法

本文系统地讨论了以动态流体双折射方法实现心血管内流场的高质量模拟测试的基本理论和实用分析方法。首先，分析了稳态流动和振荡剪切流中光──力学关系的差异，提出脉动流中简化的光──力学关系假设，然后给出其适用于低频脉动流动的实验验证。为使医学和生物力学研究人员易于掌握，又提出一种简单新颖的局域分析法。     

Bifurcation of flow and mass transport in a curved blood vessel

A numerical analysis of flow and concentration fields of macromolecules in a, slightly curved blood vessel was carried out. Based on these results, the effect of the bifurcation of a flow on the mass transport in a curved blood vessel was discussed. The macromolecules turned out to be easier to deposit in the inner part of the curved blood vessel near the critical Dean number. Once the Dean number is higher than the critical number, the bifurcation of the flow appears. This bifurcation can prevent macromolecules from concentrating in the inner part of the curved blood vessel. This result is helpful for understanding the possible correlations between the blood dynamics and atherosclerosis. The project supported by National Natural Science Foundation of China (10002003), JSPS Postdoctoral Fellowship for Foreign Researcher and Foundation for University Teachers, the Ministry of Education     

改进的六步相移法确定等倾角与等差线相位

光弹性应力分析是一种重要的实验方法,确定等倾线参数和等差线参数是光弹法的关键。常用的六步相移法可以自动确定等倾线和等差线参数,但在求解等倾角时,由于不能避免等倾线相位图中耦合等差线的影响,会造成误差。针对这个问题,本文提出优化方案--多次载荷-六步相移法,实现在等倾线相位图求解中消除等差线的影响。通过处理对称受压圆盘在不同载荷、不同光场下得到的光弹图像,实现光弹性等倾线和等差线的自动判读,验证了所提方法的可行性。     

Role of response to changes in flow rate in the regulation of vessel radius and blood flow

Estimates are presented for the effect of susceptibility of the inner surface of the blood vessel wall to shear stress on changes in diameter and volume blood flow rate. The model of thin-walled vessel with radius controlled by two parameters is used. The effect of rheological factors, hematocrit, and oxygen content in blood on the value of vessel response to a change in shear stress is considered. The estimates showed that the contribution of the vessel response in question to a change in blood volume flow rate amounts tens per cent. The influence of rheological (Fahraeus and Fahraeus-Lindqvist) effects on flow rate lies within several per cent. The role of the vessel response considered increases with anaemia: at low hematocrit its contribution to increase in flow rate exceeds 10%. Variation of oxygen concentration within the normal range has almost no effect on the hemodynamic parameters. With hypoxia, on the contrary, the participation of this response on changes in flow rate weakens: in severe hypoxia decrease in blood flow rate owing to a change in oxygen concentration equals approximately 9%.     

计算动脉血管发展流动的新差分格式

在引用守恒型N—S方程和SIMPLE方法的基础上，对血管发展流动的控制方程提出了新的差分格式。算例结果表明：本差分格式对血管发展流动的数值研究是可行的。     

THE COUPLE MOTION BETWEEN VESSEL WALL AN DBLOOD IN THE ENTRANCE REGION OF A TAPERED VESSEL

ＴＨＥＣＯＵＰＬＥＭＯＴＩＯＮＢＥＴＷＥＥＮＶＥＳＳＥＬＷＡＬＬＡＮＤＢＬＯＯＤＩＮＴＨＥＥＮＴＲＡＮＣＥＲＥＧＩＯＮＯＦＡＴＡＰＥＲＥＤＶＥＳＳＥＬＣｅｎＲｅｎ－ｊｉｎｇ（岑人经）ＱｉｎＣｈａｎ（秦婵）ＴａｎＺｈｅ－ｄｏｎｇ（谭哲东）（ＳｏｕｔｈＣ...     

A calculation method for blood flow velocity distribution in smallep elocd vessels

The calculative method presented in this paper is based on an improvement of boundary conditions for a micro-continuum fluid model with blood flow assuming that the blood cell velocity at blood vessel wall is unequal to zero. As for steady state flood flow equation (flow in vitre—a rigid circular tube) presented by Eringen, the magnitude of the blood cell gyroscopic velocity at blood vessel wall and the slope of the blood cell gyroscopic velocity distribution curve at the axis of the blood vessel are assumed. From the above mentioned assumptions the calculating method of velocity distribution curve in blood vessel is derived. The curve calculated by this method is compared with the test curve measured by Bugliarello and Hayden. The results obtained by Turk, Sylvester and Ariman as well as with this method are compared with each other, too.     

The blood flow and the motion of vessel wall

The correlation problem between the blood flow and the motion of vessel wall in the mammalian circulatory system is discussed in this paper. Supposing the blood flow is under the stable oscillatory condition, a set of formulas for velocity distribution, pressure distribution, displacement of vessel wall and constraining stress are obtained. Kuchar’s formulas are extended from steady flow to unsteady oscillatory flow by means of the formulas obtained in this paper. The problem of elasticity effect of vessel wall is also discussed.     

An analysis model of pulsatile blood flow in arteries

IntroductionTheperiodicallypulsatilebloodflowinthearterycausesthecircumferentialandaxialmotionoftheelasticbloodvesselandinturntheoscillationofthevesselaffectsthatofthebloodflow .Womersley[1]resolvedsuccessfullythisfluid_solidcouplingproblembysolvingbothlinearNavier_Stokesequationsandthemotionequationsofthethin_walledelastictubeandgainedtheexpressionsofthebloodflowvelocitiesandthevasculardisplacements.Histheoryhasbeenthebasisforthequantitativeanalysisoftherelationshipofthearterialstructureandi…     

Mathematical modeling and parametric investigation of blood flow through a stenosis artery

In this study, a mathematical model is formulated to examine the blood flow through a cylindrical stenosed blood vessel. The stenosis disease is caused because of the abnormal narrowing of flow in the body. This narrowing causes serious health issues like heart attack and may decrease blood flow in the blood vessel. Mathematical modeling helps us analyze such issues. A mathematical model is considered in this study to explore the blood flow in a stenosis artery and is solved numerically with the finite difference method. The artery is an elastic cylindrical tube containing blood defined as a viscoelastic fluid. A complete parametric analysis has been done for the flow velocity to clarify the applicability of the defined problem. Moreover, the flow characteristics such as the impedance, the wall shear stress in the stenotic region, the shear stresses in the throat of the stenosis and at the critical stenosis height are discussed. The obtained results show that the intensity of the stenosis occurs mostly at the highest narrowing areas compared with all other areas of the vessel, which has a direct impact on the wall shear stress. It is also observed that the resistive impedance and wall shear pressure get the maximum values at the critical height of the stenosis.

     

Effects of renal artery stenosis on realistic model of abdominal aorta and renal arteries incorporating fluid-structure interaction and pulsatile non-Newtonian blood flow

The effects of the renal artery stenosis(RAS) on the blood flow and vesselwalls are investigated.The pulsatile blood flow through an anatomically realistic model ofthe abdominal aorta and renal arteries reconstructed from CT-scan images is simulated,which incorporates the fluid-structure interaction(FSI).In addition to the investigationof the RAS effects on the wall shear stress and the displacement of the vessel wall,it isdetermined that the RAS leads to decrease in the renal mass flow.This may cause theactivation of the renin-angiotension system and results in severe hypertension.