标题： 湍流的自由衰减与自相似性的破坏 显示英文标题

标题： Free Decay of Turbulence and Breakdown of Self-Similarity

摘要： 自 von Karman 和 Howarth 在 1938 年的工作以来，人们普遍认为完全发展的湍流的自由衰减是自相似的。我们在这里提出了一种简单的现象学模型，用于描述三维不可压缩湍流的衰减，该模型预测在低波数谱指数$n$的范围$n_c<n<4$内自相似性会崩溃，其中$n_c$是某个临界波数。使用涡旋阻尼准正态马尔可夫近似进行计算得到该值为$n_c\approx 3.45$。此指数范围内的能量谱发展出两个长度尺度，将三个不同的波数范围分隔开。 显示英文摘要

摘要： It has been generally assumed, since the work of von Karman and Howarth in 1938, that free decay of fully-developed turbulence is self-similar. We present here a simple phenomenological model of the decay of 3D incompressible turbulence, which predicts breakdown of self-similarity for low-wavenumber spectral exponents $n$ in the range $n_c<n<4$, where $n_c$ is some threshold wavenumber. Calculations with the eddy-damped quasi-normal Markovian approximation give the value as $n_c\approx 3.45$. The energy spectrum for this range of exponents develops two length-scales, separating three distinct wavenumber ranges.