Correlations between the instantaneous velocity gradient and the evolution of scale-to-scale fluxes in two-dimensional flow.
Correlations between the instantaneous velocity gradient and the evolution of scale-to-scale fluxes in two-dimensional flow.
复制标题
二维流中瞬时速度梯度与尺度到尺度通量演化之间的相关性。
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
N. Ouellette
中科院分区：
文献类型：
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作者：
Y. Liao;N. Ouellette
使用高分辨率的粒子跟踪测速和过滤器空间技术，我们研究的尺度到尺度的能量和拟能转移和瞬时旋转和应变区域之间的联系，确定由经典的Okubo-Weiss参数在准二维实验室流。虽然Okubo-Weiss参数有缺点，我们发现，当适当的条件下，它令人惊讶的是一个很好的预测未来的演变的光谱通量。通过研究拉格朗日相关函数，我们解释我们的研究结果表明，光谱通量和Okubo-Weiss参数独立相关的长时间沿着流体元素的轨迹，因此，任何预测能力的Okubo-Weiss参数出现，因为它是耦合到流体平流。我们的研究结果表明，潜在的战略预测复杂的流动，寻找量与长拉格朗日相关时间。
Using high-resolution particle tracking velocimetry and filter-space techniques, we study the links between the scale-to-scale transfer of energy and enstrophy and instantaneously rotational and straining regions as determined by the classic Okubo-Weiss parameter in a quasi-two-dimensional laboratory flow. Although the Okubo-Weiss parameter has shortcomings, we find that, when suitably conditioned, it is surprisingly a good predictor for the future evolution of the spectral fluxes. By studying Lagrangian correlation functions, we explain our findings by showing that both the spectral fluxes and the Okubo-Weiss parameter are independently correlated for long times along fluid-element trajectories and thus that any predictive capacity of the Okubo-Weiss parameter arises because it is coupled to fluid advection. Our results suggest potential strategies for forecasting in complex flows by looking for quantities with long Lagrangian correlation times.