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首页> 外文期刊>Bulletin of the American Physical Society >APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - Volume Scaling of Intense Mixing Regions in Homogeneous Stratified Turbulence
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APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - Volume Scaling of Intense Mixing Regions in Homogeneous Stratified Turbulence

机译：APS-流体动力学APS部门第70届年会-事件-均匀分层湍流中强混合区域的体积缩放

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The spontaneous generation of localized turbulent patches or bursts in otherwise homogeneous flow is a widely accepted characteristic of stratified turbulence and can occur through many mechanisms. Here, we address this spacio-temporal variability in homogeneously forced stationary turbulence across a broad Fr-Re parameter space as realized through pseudo-spectral DNS of Boussinesq turbulence. Using a conditional averaging scheme based on local density gradient inversions, a domain is objectively subdivided into `quiescent regions', `intermittent layers' and `turbulent patches'. We observe that these regions may be characterized by an appropriate locally averaged $mathrm{Gn} equiv epsilon / u N^2$ in that they exhibit $mathrm{Gn} sim O(1)$, $mathrm{Gn} sim O(10)$, and $mathrm{Gn} sim O(100)$, respectively. We show that even at nominal bulk $mathrm{Gn}$, the majority of mixing is confined to small and intense turbulence patches. The volume of these patches scales with the bulk $mathrm{Gn}^{1/2}$.
机译：局部湍流斑块的自发产生或以其他方式均匀流动的爆发是分层湍流的广泛接受的特征，并且可以通过许多机制发生。在这里，我们解决了通过Boussinesq湍流的伪光谱DNS实现的，在整个Fr-Re参数空间内均等强迫平稳湍流中的时空变化。使用基于局部密度梯度反演的条件平均方案，将域客观地细分为“静态区域”，“间歇层”和“湍流斑块”。我们观察到这些区域的特征可能在于适当的局部平均$ mathrm {Gn}等值epsilon / u N ^ 2 $，因为它们表现出$ mathrm {Gn} sim O（1）$，$ mathrm {Gn} sim O（ 10）$和$ mathrm {Gn} sim O（100）$。我们证明，即使在名义体积$ mathrm {Gn} $的情况下，大多数混合也仅限于小而剧烈的湍流斑块。这些补丁的数量与$ mathrm {Gn} ^ {1/2} $的大小成比例。

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