REVERSAL OF THE BERNOULLI EFFECT AND CHANNEL FLUTTER
REVERSAL OF THE BERNOULLI EFFECT AND CHANNEL FLUTTER
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伯努利效应和通道颤振的逆转
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
Lixi Huang
中科院分区：
文献类型：
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作者：
Lixi Huang
摘要本文研究了输流柔性管的坍塌及其自激振动。我们的模型考虑了一个二维的，无粘的，剪切流在一个灵活的渠道无限长的线性，旅行静脉曲张波。边界值问题的分析导致了两个发现，这似乎没有被注意到之前，尽管密切关注这种流体-结构相互作用已经吸引了由于其医学意义。壁面上的压力扰动有两个分量，第一个分量与壁面位移同相，第二个分量与壁面运动速度同相。对于势流，第一个分量是唯一趋于不稳定的分量，被称为伯努利效应。然而，对于剪切流，由于涡量场的扰动克服了伯努利效应，压力的符号相反。流线图表明，开尔文的“猫眼”在较宽的通道部分被遮蔽，使得物理宽度较大的有效流道较小。第二个分量产生波阻，因此能量从流到波的不可逆传递。我们认为，这是一个可能的机制，在实验中观察到的自激振荡。这种机制类似于Miles（1957）的风引起水波的机制，根据Benjamin-Landahl分类，它是一种B类不稳定性，但是伴随的伯努利效应的逆转是不同的，并且基本上取决于第二边界的存在。本征值问题也被认为是和它表明，长，但有限波长的动态不稳定性，可以经历由顺应通道厚壁，一个典型的应用是在上呼吸道的呼吸流。根据通道特性给出了临界流速。
Abstract This paper is concerned with the collapse and subsequent self-excited oscillation of compliant tubes conveying fluids. Our model considers a two-dimensional, inviscid, shear flow in a flexible channel of infinite length subject to linear, travelling varicose waves. Analysis of the boundary-value problem leads to two findings which do not seem to have been noticed before, despite the close attention this kind of fluid–structure interaction has attracted on account of its medical significance. The pressure perturbation on the wall has two components, the first is in-phase with the wall displacement and the second with the velocity of the wall motion. For potential flow, the first component is the only one tending to destabilize and is known as the Bernoulli effect. For shear flow, however, the sign of the pressure is reversed as the Bernoulli effect is overcome by the perturbations of the vorticity field. Streamline patterns show that Kelvin's “cats' eyes” are sheltered in the wider channel sections, rendering the effective flow passage smaller where the physical width is larger. The second component produces a wave drag, hence irreversible transfer of energy from the flow to waves. We argue that this is a possible mechanism for the self-excited oscillation observed in experiments. This mechanism is similar to Miles's (1957) mechanism of water wave generation by wind, which is a class B instability according to the Benjamin–Landahl categorization, but the accompanying reversal of the Bernoulli effect is different and depends essentially on the presence of a second boundary. The eigenvalue problem is also considered and it is shown that dynamic instability of long but finite wavelength could be experienced by compliant channels with thick walls, a typical application being the respiratory flow in the upper airways. The critical flow speed is given in terms of the channel properties.