Bend Sweep Angle and Reynolds Number Effects on Hemodynamics of S-Shaped Arteries
Bend Sweep Angle and Reynolds Number Effects on Hemodynamics of S-Shaped Arteries
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弯曲扫描角和雷诺数对 S 形动脉血流动力学的影响
DOI：
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发表时间：
2010
影响因子：
3.8
通讯作者：
E. R. Jaghargh
中科院分区：
文献类型：
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作者：
H. Niazmand;E. R. Jaghargh
本研究旨在探讨雷诺数及弯曲后掠角对S形弯管血流型态的影响。对雷诺数为125、500和960时，后掠角分别为45°、90°和135°的S形弯管内的定常流动进行了数值模拟。血流动力学特性，如二次流，涡，轴向速度分布进行了详细分析。S形弯管内的流型与雷诺数和弯曲后掠角密切相关，根据第一个弯曲的二次流对第二个弯曲横向流动的影响，S形弯管内的流型可分为三类。对于低雷诺数和任何后掠角，第二弯曲中的二次流消除了第二弯曲的早期部分中的第一弯曲效应，因此轴向速度分布与弯曲曲率一致，而对于取决于弯曲后掠角的高雷诺数，第一个弯曲的二次涡型可以部分地或全部地在整个第二个弯曲中持续，导致四个-旋涡二级结构此外，在雷诺数为960时观察到的一个有趣的流动特征是，二次流不对称行为发生在第二弯曲出口附近和沿着流出直段。与本文所考虑的其他模型相比，在先前的研究中没有报道的这种断裂现象在90° S形弯曲中显示出更明显。作为动脉壁疾病发生和发展的重要流动特征之一的流动分离的可能性也进行了研究。结果表明，在足够高的雷诺数下，后掠角为20° ~ 30°的平缓弯管的第二弯曲外壁容易发生流动分离。
The purpose of this study is to investigate the effects of the Reynolds number and the bend sweep angle on the blood flow patterns of S-shaped bends. The numerical simulations of steady flows in S-shaped bends with sweep angles of 45°, 90°, and 135° are performed at Reynolds numbers of 125, 500, and 960. Hemodynamic characteristics such as secondary flows, vorticity, and axial velocity profiles are analyzed in detail. Flow patterns in S-shaped bends are strongly dependent on both Reynolds number and bend sweep angle, which can be categorized into three groups based on the first bend secondary flow effects on the transverse flow of the second bend. For low Reynolds numbers and any sweep angles, secondary flows in the second bend eliminate the first bend effects in the early sections of the second bend and therefore the axial velocity profile is consistent with the bend curvature, while for high Reynolds numbers depending on the bend sweep angles the secondary vortex pattern of the first bend may persist partially or totally throughout the second bend leading to a four-vortex secondary structure. Moreover, an interesting flow feature observed at the Reynolds number of 960 is that the secondary flow asymmetrical behavior occurred around the second bend exit and along the outflow straight section. This symmetry-breaking phenomenon which has not been reported in the previous studies is shown to be more pronounced in the 90° S-shaped bend as compared to other models considered here. The probability of flow separation as one of the important flow features contributing to the onset and development of arterial wall diseases is also studied. It is observed that the second bend outer wall of gentle bends with sweep angles from 20° to 30° at high enough Reynolds numbers are prone to flow separation.
影响因子：
3.7
作者：
Blackburn, H. M.;Sherwin, S. J.;Barkley, D.
通讯作者：
Barkley, D.