LoGerfo F W, Nowak M D, Quist W C
J Vasc Surg. 1985 Mar;2(2):263-9.
We have used a dye-flow visualization technique to analyze the substructure of flow separation in a plastic model of the human carotid bifurcation under steady and pulsatile flow. Under steady conditions at a physiologic flow split (Q external carotid/Q common carotid = 0.30) and Reynolds number (500), a large region of separated fluid developed along the outside wall of the sinus, opposite the flow divider. Yellow dye injected into the boundary layer upstream from the bifurcation traveled slowly along the wall of the common carotid and entered directly into the separation. Blue dye injected into the central, high-velocity streamlines in the common carotid impacted on the flow divider, then traveled circumferentially and entered the separation. Mixing of these two sources was documented by the appearance of green fluid, which lingered in the region of separation. Pulsatile flow resulted in a smaller region of separation; mixing still occurred. Flow separation at the carotid bifurcation is a site of mixing of fluids previously subjected to prolonged low-shear wall contact and brief high-shear wall contact. Separation is itself a site of low shear, but this study reveals a mechanism whereby low and high shear may act independently or synergistically to explain the link between flow separation and atherogenesis.
我们采用了一种染料流动可视化技术，在稳定流和脉动流条件下，对人体颈动脉分叉处塑料模型中的流动分离亚结构进行分析。在稳定条件下，当生理血流分流比（颈外动脉血流/颈总动脉血流 = 0.30）和雷诺数为500时，在与分流器相对的窦外壁处形成了一大片分离流体区域。注入分叉上游边界层的黄色染料沿着颈总动脉壁缓慢流动，并直接进入分离区域。注入颈总动脉中央高速流线的蓝色染料撞击分流器，然后沿圆周方向流动并进入分离区域。这两种染料源的混合通过绿色流体的出现得以记录，绿色流体在分离区域持续存在。脉动流导致分离区域变小，但混合仍会发生。颈动脉分叉处的流动分离是先前经历长时间低剪切壁面接触和短暂高剪切壁面接触的流体混合的部位。分离本身是一个低剪切部位，但本研究揭示了一种机制，通过该机制，低剪切和高剪切可能独立或协同作用，以解释流动分离与动脉粥样硬化形成之间的联系。
