Stratified inclined duct: two-layer hydraulics and instabilities
Stratified inclined duct: two-layer hydraulics and instabilities
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分层倾斜风管：两层水力学和不稳定性
DOI：
10.1017/jfm.2023.871
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发表时间：
2023
影响因子：
3.7
通讯作者：
Atoufi A
中科院分区：
文献类型：
--
作者：
Atoufi A
分层倾斜导管（SID）维持交换流在一个长的，轻轻倾斜的管道作为一个模型，连续强迫密度分层流，如那些发现在河口。实验表明，出现的界面波和它们的过渡到湍流的倾斜角的增加似乎是链接到一个阈值的交换流量由无粘性的两层水力。我们通过以下方式揭示这些水力机制：（i）使用最近的直接数值模拟（DNS），提供关键流态中的全流数据（Zhu等人，流体力学杂志，vol.969，2023，A20），（ii）将这些DNS平均为两层，以及（iii）使用非粘性两层浅水和不稳定理论来诊断界面波行为并提供物理见解。层流在整个管道中是亚临界和稳定的，并在管道的端部处受到液压控制。随着倾斜度的增加，流动在各处都变得超临界，并且对长波不稳定。具有驻波的内部跳跃首先出现在管道的中心附近，然后导致更大振幅的行波，并在最大倾斜角处导致更强的跳跃、波破碎和间歇性湍流。长波描述的（非线性）浅水方程被解释为局部线性波的两层平行的底流描述的泰勒-戈尔茨坦方程。这种联系有助于我们解释长波不稳定性，并将其与短波（如开尔文-亥姆霍兹）不稳定性进行对比。我们的研究结果表明，通过长波不稳定性依赖于垂直限制的顶部和底部的墙壁在SID湍流的过渡。
The stratified inclined duct (SID) sustains an exchange flow in a long, gently sloping duct as a model for continuously forced density-stratified flows such as those found in estuaries. Experiments have shown that the emergence of interfacial waves and their transition to turbulence as the tilt angle is increased appears to be linked to a threshold in the exchange flow rate given by inviscid two-layer hydraulics. We uncover these hydraulic mechanisms by (i) using recent direct numerical simulations (DNS) providing full flow data in the key flow regimes (Zhu et al., J. Fluid Mech., vol. 969, 2023, A20), (ii) averaging these DNS into two layers, and (iii) using an inviscid two-layer shallow-water and instability theory to diagnose interfacial wave behaviour and provide physical insight. The laminar flow is subcritical and stable throughout the duct and hydraulically controlled at the ends of the duct. As the tilt is increased, the flow becomes supercritical everywhere and unstable to long waves. An internal jump featuring stationary waves first appears near the centre of the duct, then leads to larger-amplitude travelling waves, and to stronger jumps, wave breaking and intermittent turbulence at the largest tilt angle. Long waves described by the (nonlinear) shallow-water equation are interpreted locally as linear waves on a two-layer parallel base flow described by the Taylor–Goldstein equation. This link helps us to interpret long-wave instability and contrast it with short-wave (e.g. Kelvin–Helmholtz) instability. Our results suggest a transition to turbulence in SID through long-wave instability relying on vertical confinement by the top and bottom walls.
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分层倾斜风管：直接数值模拟
影响因子：
3.7
作者：
Lu Zhu;Amir Atoufi;A. Lefauve;John R. Taylor;R. Kerswell;S. Dalziel;G. Lawrence;P. Linden
通讯作者：
P. Linden
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DOI：
--
发表时间：
2002
期刊：
影响因子：
--
作者：
M. Gregg;E. Özsoy
通讯作者：
E. Özsoy
影响因子：
3.7
作者：
Lefauve, Adrien;Partridge, J. L.;Linden, P. F.
通讯作者：
Linden, P. F.
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影响因子：
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作者：
M. Duran‐Matute;S. J. Kaptein;H. Clercx
通讯作者：
H. Clercx
两层流体系统中的液压跳跃
DOI：
--
发表时间：
1955
期刊：
影响因子：
--
作者：
C. Yih;C. Guha
通讯作者：
C. Guha