Structural evolution of intermittency and anisotropy at different scales analyzed using three‐dimensional wavelet transforms
Structural evolution of intermittency and anisotropy at different scales analyzed using three‐dimensional wavelet transforms
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使用三维小波变换分析不同尺度的间歇性和各向异性的结构演化
DOI：
10.1063/1.858441
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发表时间：
1992
影响因子：
4.6
通讯作者：
Qunzhen Wang
中科院分区：
文献类型：
--
作者：
J. Brasseur;Qunzhen Wang
三维墨西哥帽小波变换被用作傅立叶谱空间滤波器，以研究（1）运动方程中的非线性产生间歇性集中涡量区域的过程，以及（2）各向同性湍流通过平均剪切变为各向异性的过程。在第一项研究中，三维小波变换被应用于从高斯初始条件到各向同性湍流的过渡的直接数值模拟。在这个过渡过程中，最初的非相干涡量场被转化的Navier-Stokes非线性相干区域的集中涡量。对小波变换涡度拟能场的分析表明：（a）小尺度总是比大尺度更具有间歇性;（B）小尺度上的湍流度水平比大尺度上增长得更快;最重要的是（c）不同尺度上湍流的结构发展与湍流的演变和发展都有关系。
The three‐dimensional Mexican hat wavelet transform is used as a Fourier‐spectral space filter to study (1) the process by which the nonlinearities in the equations of motion create intermittent regions of concentrated vorticity and (2) the process by which isotropic turbulence becomes anisotropic by mean shear. In the first study, the three‐dimensional wavelet transform is applied to direct numerical simulations of the transition from Gaussian initial conditions to isotropic turbulence. During this transition, the initially noncoherent vorticity field is transformed by the Navier–Stokes nonlinearities into coherent regions of concentrated vorticity. Analysis of the wavelet‐transformed enstrophy field suggests (a) that small scales are always more intermittent than large scales, (b) that the level of intermittency at the small scales grows more rapidly than at the large scales, and most importantly (c) that the structural development of turbulence at different scales is correlated both with the evolution ...