arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1808.06186physics.flu-dyncond-mat.softcond-mat.stat-mechnlin.CDphysics.geo-ph
收藏

湍流中的叶栅和转捩

Cascades and transitions in turbulent flows

A. Alexakis, L. Biferale

摘要:

湍流的特征在于能量和其他无粘不变量的非线性级联,这些能量和不变量从它们注入的地方到它们消散的地方跨越了巨大的尺度范围。最近,新的实验,数值和理论工作表明,许多湍流配置偏离理想的三维/二维各向同性的情况下,其特征在于存在一个严格的直接/反向的能量级联,分别。我们回顾最近的作品从一个统一的角度来看,我们提出了一个分类的所有已知的转移机制。除了经典的直接和反向级联的情况下,不同的情况下,包括:分裂级联到小和大规模的同时,多/双级联的不同数量,双向级联的直接和反向转移相同的不变量共存于相同的规模范围内,最后平衡态,其中没有级联,包括当冷凝物形成的情况下。我们将所有的过渡控制参数的变化,我们分析何时以及为什么观察到不同的配置。我们的讨论是基于一组典型的应用:螺旋湍流,旋转和/或分层流,MHD和被动/主动标量的传输特性被改变作为一个改变的嵌入尺寸,域的厚度或其他相关的控制参数,如雷诺数,Rossby,弗劳德,Peclet,或阿尔芬数。我们讨论了与组态空间中能量耗散的间歇性有关的反常标度律的存在。还提供了一个概述有关级联在其他应用中,如有界流,量子,相对论和可压缩湍流,和活性物质,以及湍流建模的影响。最后,我们提出了一系列开放的问题和挑战,未来的工作需要解决。

英文摘要:

Turbulence is characterized by the non-linear cascades of energy and other inviscid invariants across a huge range of scales, from where they are injected to where they are dissipated. Recently, new experimental, numerical and theoretical works have revealed that many turbulent configurations deviate from the ideal 3D/2D isotropic cases characterized by the presence of a strictly direct/inverse energy cascade, respectively. We review recent works from a unified point of view and we present a classification of all known transfer mechanisms. Beside the classical cases of direct and inverse cascades, the different scenarios include: split cascades to small and large scales simultaneously, multiple/dual cascades of different quantities, bi-directional cascades where direct and inverse transfers of the same invariant coexist in the same scale-range and finally equilibrium states where no cascades are present, including the case when a condensate is formed. We classify all transitions as the control parameters are changed and we analyse when and why different configurations are observed. Our discussion is based on a set of paradigmatic applications: helical turbulence, rotating and/or stratified flows, MHD and passive/active scalars where the transfer properties are altered as one changes the embedding dimensions, the thickness of the domain or other relevant control parameters, as the Reynolds, Rossby, Froude, Peclet, or Alfven numbers. We discuss the presence of anomalous scaling laws in connection with the intermittent nature of the energy dissipation in configuration space. An overview is also provided concerning cascades in other applications such as bounded flows, quantum, relativistic and compressible turbulence, and active matter, together with implications for turbulent modelling. Finally, we present a series of open problems and challenges that future work needs to address.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑