Experiments with mixing in stratified flow over a topographic ridge
Experiments with mixing in stratified flow over a topographic ridge
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地形山脊上的分层流混合实验
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
M. Copeland
中科院分区：
文献类型：
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作者：
R. W. Griffiths;Y. Dossmann;M. G. Rosevear;A. Hogg;G. Hughes;M. Copeland
准定常深海洋流与海底地形的相互作用预计会在海洋中产生湍流混合。这种混合可能发生在局部，靠近地形，或通过打破准稳定的背风波，可以携带能量进入海洋内部。目前还没有关于局部和内部混合的相对量的理论或经验推导的预测。我们报告测量的混合率在实验室实验中的地形山脊拖通过密度分层。实验跨越三个参数制度，包括线性背风波，非线性流和倏逝制度，其中波辐射是弱的。全场密度测量提供的深度依赖性的能量损失的湍流混合，允许分离的本地混合的湍流尾流和远程混合波辐射。远程混合是显着的，只有一个狭窄的频带的强迫参数的流速是共振与内波;在所有其他参数制度的本地混合接近的地形是占主导地位的。结果表明，混合的本地非线性机制接近深海海洋地形可能远远大于远程混合准定常背风波。本文受版权保护。All rights reserved.
The interaction of quasi-steady abyssal ocean flow with submarine topography is expected to generate turbulent mixing in the ocean. This mixing may occur locally, close to topography, or via breaking quasi-steady lee waves that can carry energy into the ocean interior. There is currently no theoretical, or empirically-derived, prediction for the relative amounts of local and interior mixing. We report measurements of the mixing rate in laboratory experiments with a topographic ridge towed through a density stratification. The experiments span three parameter regimes including linear lee waves, nonlinear flow and an evanescent regime in which wave radiation is weak. Full field density measurements provide the depth-dependence of energy loss to turbulent mixing, allowing separation of the local mixing in the turbulent wake and remote mixing by wave radiation. Remote mixing is significant only for a narrow band of forcing parameters where the flow speed is resonant with internal waves; in all other parameter regimes local mixing close to the topography is dominant. The results suggest that mixing by local nonlinear mechanisms close to abyssal ocean topography may be much greater than the remote mixing by quasi-steady lee waves. This article is protected by copyright. All rights reserved.