School of Aeronautics, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
Science. 2017 Aug 25;357(6353):782-784. doi: 10.1126/science.aan7933. Epub 2017 Aug 17.
To the naked eye, turbulent flows exhibit whirls of many different sizes. To each size, or scale, corresponds a fraction of the total energy resulting from a cascade in five dimensions: scale, time, and three-dimensional space. Understanding this process is critical to strategies for modeling geophysical and industrial flows. By tracking the flow regions containing energy in different scales, we have detected the statistical predominance of a cross-scale link whereby fluid lumps of energy at scale Δ appear within lumps of scale 2Δ and die within those of scale Δ/2. Our approach uncovers the energy cascade in a simple water-like fluid, offering insights for turbulence models while paving the way for similar analyses in conducting fluids, quantum fluids, and plasmas.
肉眼可见，湍流中显现出大小不一的漩涡。对于每个大小或尺度，都对应着五维级联（尺度、时间和三维空间）中总能量的一部分。理解这个过程对于地球物理和工业流动的建模策略至关重要。通过跟踪含有不同尺度能量的流区，我们检测到了跨尺度的连接的统计优势，其中在尺度Δ的能量团块内出现了尺度为 2Δ 的团块，并在尺度Δ/2 的团块内消失。我们的方法揭示了简单水状流体中的能量级联，为湍流模型提供了见解，同时为在传导流体、量子流体和等离子体中进行类似的分析铺平了道路。
