Enhanced effects from tiny flexible in-wall blips and shear flow
Enhanced effects from tiny flexible in-wall blips and shear flow
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DOI：
10.1017/jfm.2015.193
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发表时间：
2015-06-01
影响因子：
3.7
通讯作者：
Smith, Frank
中科院分区：
文献类型：
--
作者：
Pruessner, Luisa;Smith, Frank
在高雷诺数的流体运动在一个灵活的壁内blip（一个顺从的隆起或下降，否则固定的墙壁）被认为是理论上为一个非常短的blip埋在边界层内低。只有来流的近壁面剪切作用影响通过微小光点的局部运动。首先检查缓慢演变的特征，以考虑入射流的变化。线性和非线性的解决方案表明，在某些参数值（特征值）的强化发生在流量和斑点形状的相互作用的影响是由一个数量级比在大多数参数值大。类似的发现也适用于存在几个微小光点的边界层或存在几乎任何长度光点的槽道流。这些强化导致完全非线性的非定常运动作为第二阶段，经过一定的延迟，从而结合有限时间的分裂，形成一个独特的路径到过渡的流动。
Fluid motion at high Reynolds number over a flexible in-wall blip (a compliant bump or dip in an otherwise fixed wall) is considered theoretically for a very short blip buried low inside a boundary layer. Only the near-wall shear of the oncoming flow affects the local motion past the tiny blip. Slowly evolving features are examined first to allow for variations in the incident flow. Linear and nonlinear solutions show that at certain parameter values (eigenvalues) intensifications occur in which the interactive effect on flow and blip shape is larger by an order of magnitude than at most parameter values. Similar findings apply to the boundary layer with several tiny blips present or to channel flows with blips of almost any length. These intensifications lead on to fully nonlinear unsteady motion as a second stage, after some delay, thus combining with finite-time breakups to form a distinct path into transition of the flow.