Model experiments in vitro and numerical simulation on the interaction between pulsatile blood flow and elastic blood vessel

（一）.采用实验和数值模拟相结合的方法，研究了高柔度血管模型薄壁可折叠管的屈曲和大变形问题。用激光片光法显示出随跨壁压下降而塌陷的管截面的变化轮廓，并由轮廓所围成的内部区域求出横截面积。由此测量的轮廓形状与使用二维和三维理论模型计算的轮廓形状一致。根据上述理论和实验，并结合传统的测量管道塌陷位移体积的方法，得到了管道定律，即管道横截面积与跨壁压的关系。比较表明，在整个t区域内，三维理论计算结果与实验结果符合得很好 ...更多信息 而二维理论在管两端的刚性连接的未受影响的区域中这样做。用二维流动理论可以较好地预测稳定流通过塌缩管时沿管轴沿着的压力分布。（二）、将直径约10 μ m的海藻酸凝胶的软弹性球形颗粒在水和生理盐溶液中的高浓度悬浮液开发为模型血液。该模型血液符合τ对d γ/dt的卡森图，其具有与真实的人血液相同的表观粘度和相似的屈服应力。此外，从使用具有高速摄像机的流变仪的实验中，在低于约100/秒的低剪切速率的区域中，显示出由凝胶颗粒的聚集体引起的异常高的剪切应力，这是与当剪切速率低于约100/秒时真实的血细胞形成红细胞叠连非常相似的现象。（三）、通过柔性管和刚性管灌注上述模型血液，以比较其流动特性与水的流动特性。其结果是，它们之间的一个明显的区别，显示如下：在两个管的速度分布在模型血液的流动有更多的圆形相比，在水流中，无论层流或湍流。因此，它可以作为真实的血液的强有力的替代物，在各种体外实验中模拟真实的血液流动。少

(1). The buckling and large deformation of collapsible tubes with very thin wall thickness as a model of blood vessel with high compliance was investigated both by experiments and numerical simulation. A changing contour of the cross section of the tube collapsing with the decrese in the transmural pressure was visualized by laser light sheet, and the cross sectional area was obtained from the internal area surrounded by the contour. The shape of the contour thus measured agreed well with that calculated using two-dimensional and three-dimensional theoretical models. Thus the tube law, i.e. the relationship between the cross sectional area of the tube and the transmural pressure was obtained both from the above-mentioned theories and experiment together with a conventional method of measuring the displaced tube volume due to collapse. Comparison between them revealed that the results from the three-dimensional theory agreed well with that from the experiments in the overall region of t … More he tube while the two-dimensional theory did so in the unaffected region by rigid connections at both ends of the tube. Pressure distribution along the tube axis in steady flow through the collapsed tube were able to be predicted fairly by the two-dimensional flow theory.(2). A high concentration suspension of soft and elastic spherical particles of alginic acid gel having diameter of about 10 mu m in water and physiological salt solution was developed as a model blood. This model blood obeyed the Casson's diagram of tau versus d gamma /dt which had the same apparent viscosity and a similar yield stress as the real human blood. Furthermore, from the experiments using a rheoscope with a high spped video camera, in the region of low shear rate less than about 100/sec, an abnormally high shear stress was shown which was caused by an aggregate of the gel particles, which is a very similar phenomenon as real blood cell forms a rouleaux when the shear rate is lower than about 100/sec.(3). The above-mentioned model blood was perfused through both a flexible tube and a rigid one to compare its flow characteristics with that of water. As a result, a clear difference between them was shown as follows ; velocity profiles across the both tubes in the flow of the model blood had more round shape compared with those in water flow regardless of laminar or turbulent flow. Hence, it can be used as a powerful substitute of real blood invarious experiments in vitro to simulate real blood flow. Less