Hemodynamic parameters on the macromolecular transport between serum and blood vessel wall

1.腹主动脉瘤模型中的脉动流和壁应力：用流动显示方法研究了模拟梭形和侧方囊状动脉瘤的玻璃模型中的脉动流。在加速阶段的初始阶段，血流开始从动脉瘤的近端壁分离。然后，分隔的气泡或漩涡迅速增大，并在周围填满整个动脉瘤区域。在这段时间内，涡旋的中心从动脉瘤的近端移动到远端。例如，可能发生在射血期结束时的瞬时反转流动通过动脉瘤壁和中心位置的涡流之间。当血流速度和脉动频率较高时，旋涡在动脉瘤远端破裂为湍流。随着动脉瘤长度的增加，也观察到同样的效果。脉动幅度的减小使流型接近t…。更多的帽子在稳定的流动中。对脉动流在轴对称扩张管内的速度场和压力场进行了有限元分析。计算得到的速度场和流线与实验结果吻合较好。扩张区涡旋的出现和消失及其发展导致压力场和剪切场的复杂分布。当流量达到峰值时，壁面剪应力的局部最小值和最大值出现在膨胀器远端的上下游。数值研究了动脉瘤模型在加载壁面剪应力和内壁压力的情况下壁面应力分布。它依赖于压力而不是壁面剪应力载荷。结论：1.管壁剪应力集中发生在动脉瘤的中远段。脉动流经人颈动脉：通过可视化实验来阐明脉动流经透明的人颈动脉的复杂流型。在脉动流中观察到了与圆形管壁突起周围产生的马蹄涡相似的螺旋回流，通过本研究中使用的所有分支。在雷诺数大于100的定常流动中，马蹄涡也被证明发生在人的颈总动脉分叉处。时变流动也主要在减速阶段产生马蹄涡。当螺旋流产生时，停滞点出现在顶端上游的壁上。它们的位置取决于各个动脉分支之间的流量分配比。在分支血管的外壁或内壁观察到分离气泡。在动脉分支处对垂直于管轴的管壁进行应力分析。上壁内壁和外壁可见张力性和压力性。在未来的研究中，将更多地关注量化血管壁机械性能与动脉疾病之间的关系。较少

1. Pulsatile Flow and wall stress in Models of the Abdominal Aortic Aneurysm: Pulsatile Flows in glass models simu-lating fusiform and lateral saccular aneurysms were investigated by a flow visualization method. At the initial stage of accelerating phase, the flow began to separate from the proximal wall of the aneurysm. Then the saparate bubble or vortex grew rapidly in size and filled the whole area of the aneurysm circumferentially. During this period of time, the center of the vortex moved from the proximal end to the distal point of the aneurysm. The transient reversal flow, for instance, which may occur at the end of the ejection period, passed between the wall of the aneurysm and the centrally located vortex. When the rate and pulsatile frequency of flow were high, the vortex broke down into turbulence at the distal portion of aneurysm. The same effect was observed when the length of the aneurysm was increased. A re-duction in pulsatile amplitude made the flow pattern close to t … More hat in steady flow. A finite element analysis was made to obtain velocity and pressure fields in pulsatile flow through a tube with an axisymmetric expansion. Caluculated in stantaneous patters of velocity field and stream lines agreed well with the experimental results. The appearance and disapperance of the vortex in the dilated portion and its development resulted in complex distributions of pressure and shear fields. Locally minimum and maximum values of wall shear stress occured at points just upstream and down stream of the distal end of the expansion when the flow rate reached ist peak. Wall stress distribution was investigated nu-merically as the result of loading wall shear stress and pressure on inner wall of the aneurysm model. It was depended upon presuure than wall shear stresss loading. The shear stress concentration in the wall was generated between middle and distal portion of the aneurysm.2. Pulsatile Flow Through the Human Carotid Arteries: Visualization experiments were performed to elucidate the complicated flow pattern in pulsatile flow thorugh the human carotid arteries which were made transparent. Helically recirculating flow with a pattern similar to that of the horseshoe vortex produced around wall-based protuberances in circular tubes was observed in pulsatile flow through all the bifurcations used in the present study. The horseshoe vortex has also been demonstrated to occure at the human common carotid bifurcation in steady flow with reynolds number above 100. Time-varying flows also produced the horseshoe vortex mostly during the decelerating phase. While this helical flow was produced, the stagnation points appeared on the wall upstream of the apex. Their position was dependent upon the flow distribution ratio between braches in the individual arteries. A separation bubble was observed at the outer or inner wall of the branch vessels.3. Stress analysis in the wall perpendicular to tube axis was performed at arterial branch site. Tension and compressionwere seen at the inner and outer wall on the line of apsides. The more attension toward quantiating the relationship between the mechanical properties of the vessel wall and arterial disease is disired in the future study. Less