Pulsatile flow in curved pipes
Pulsatile flow in curved pipes
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DOI：
10.1017/s0022112075002418
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发表时间：
1975-09
影响因子：
3.7
通讯作者：
F. Smith
中科院分区：
文献类型：
--
作者：
F. Smith
当流体被驱动通过弯曲管时发生的一些流动的特性被公开用于脉动性质的施加的压力梯度，其关于非零平均值随时间正弦地变化。充分发展的运动取决于三个参数：传统的迪恩数D、与频率相关的参数β和二次雷诺数Rs，假设管道的曲率半径远大于其横截面尺寸。流场的理论描述从迄今为止研究的定常和纯振荡极限扩展到当Rs为单位阶数而其它参数β或D取大或小值时出现的所有关键情况。在这种分析过程中，在某些情况下，涉及到稳定的边界层和斯托克斯层之间的相互作用，一些脉动运动被揭示和方式，其中在高频率的二次运动可以改变其方向，从向内的"“向外，也被解释。从定常极限出发，对脉动运动作了两个进一步的说明，当Rs ≥ 1时，产生了从定常附面层流动到附面层流动的另一种过渡模式。这项研究，主要涉及在任意横截面的流动，奠定了一个正式的基础，推导出许多物理情况下，其中一些是可表达的重要修改，或组合，流动问题，其属性已经赞赏的基本属性。
The characteristics of some flows that occur when fluid is driven through a curved tube are disclosed for an imposed pressure gradient of pulsatile nature, varying sinusoidally with time about a non-zero mean. The fully developed motion depends on three parameters, a traditional Dean number D, a frequencyrelated parameter β and a secondary Reynolds number Rs, it being assumed that the pipe's radius of curvature is much greater than its cross-sectional dimensions. The theoretical description of the flow field is extended from the steady and purely oscillatory limits hitherto studied to all the key situations arising when Rs is of order unity and one of the other parameters β or D takes a large or small value. During this analysis, which in certain cases involves the interactions between steady boundary layers and Stokes layers, a number of pulsatile motions are revealed and the manner in which at high frequencies the secondary motion can change its direction, from inward ‘centrifuging’ to outward, is also explained. Two further illustrations of pulsating motions, stemming from the steady limit, produce an alternative mode of transition from steady boundary-layer flow to the boundary-layer flows occurring when Rs ∼ 1. The study, which mainly deals with the flow in an arbitrary cross-section, lays down a formal basis for deriving the fundamental attributes of many physical situations, some of which are expressible in terms of crucial modifications to, or combinations of, flow problems whose properties are already appreciated.