Observation of Intense Filaments in Fully Developed Turbulence
Observation of Intense Filaments in Fully Developed Turbulence
复制标题
充分发展的湍流中强烈细丝的观察
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
H. Willaime
中科院分区：
文献类型：
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作者：
F. Belin;J. Maurer;P. Tabeling;H. Willaime
本文研究了氦实验中控制速度导数波动尾的大事件的结构。当R λ < 700时，我们发现这些事件具有显著的结构，这与以前在数值研究中观察到的强涡旋细丝（蠕虫）一致。这些物体的特征（形状、大小和循环分布，与雷诺数成比例）与报道的数值结果很好地一致。这些对象对总耗散的贡献不大，但它们控制着惯性范围内的重要部分间歇性。在R λ 700以上，这类事件的结构发生了巨大变化；我们把这种观察结果解释为不稳定性。我们最后对先前的实验提供了物理解释，表明在R λ 700附近，速度导数的平坦度表现出过渡行为。
We study the structure of the large events which control the tails of the pdf of the velocity derivatives in an helium experiment. For R λ < 700, we find that these events have a remarkable structure, which is consistent with that of intense vortex filaments (worms) observed previously in numerical studies. The characteristics of such objects (form, size and circulation distributions, scaling with the Reynolds number) are in good agreement with reported numerical findings. These objects do not contribute significantly to the overall dissipation but they control an important part of the intermittency in the inertial range. Above R λ 700, the structure of such events dramatically changes; we interpret this observation as an instability. We finally offer a physical interpretation of a previous experiment showing that around R λ 700, the flatness of the velocity derivatives shows a transitional behaviour.