Back L H, Kwack E Y, Crawford D W
Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
Monogr Atheroscler. 1990;15:96-108.
Steady flow observations in a smooth curved femoral artery model with a gradual bend revealed a flow pattern like that observed in coiled pipes. A double helical type flow was found to develop, with converging streamlines in the wall vicinity from the upper and lower plane of curvature merging asymptotically along the inner curvature in a stable manner. The helical or swirl angle of the labeled fluid particle paths increased with flow rate and thus Dean number. Flow in the wall vicinity was altered by centrifugal effects almost immediately downstream of the transition from the straight to curved segment for steady flow, although the propagation of this effect was observed farther downstream along the inner curvature side. This observed distance along the inner curvature became shorter with increasing Dean number. Pressure measurements for steady flow revealed progressively larger pressure drops with distance along the entrance region of the curved segment relative to that for a straight lumen. The overall pressure drop or flow resistance increased in a nonlinear way with increasing flow rate and thus Dean number. Time average pressure drop measurements across another similar smooth curved femoral model were found to be about the same for simulation of femoral artery pulsatile flow as for steady flow.
在具有逐渐弯曲的光滑弯曲股动脉模型中的定常流观测显示出一种类似于在盘管中观察到的流动模式。发现会形成一种双螺旋型流动，壁面附近来自曲率上下平面的流线以稳定的方式沿着内曲率渐近合并。标记流体粒子路径的螺旋角或涡旋角随流速以及因此的迪恩数增加。对于定常流，在从直管段过渡到弯管段后几乎立即在下游，壁面附近的流动就受到离心效应的改变，尽管这种效应的传播在内曲率侧沿下游更远的地方被观察到。沿着内曲率观察到的这个距离随着迪恩数的增加而变短。定常流的压力测量显示，相对于直管腔，沿着弯曲段入口区域，压力降随着距离逐渐增大。总压力降或流动阻力随着流速以及因此的迪恩数增加而非线性增加。发现在模拟股动脉脉动流时，跨另一个类似的光滑弯曲股动脉模型的时间平均压力降测量值与定常流时大致相同。
