Scale analysis of turbulent channel flow with varying pressure gradient  

作　　者：邱翔 罗剑平 黄永祥 卢志明 刘宇陆 

机构地区：[1]School of Science,Shanghai Institute of Technology [2]School of Mechanical Engineering,Shanghai Institute of Technology [3]Shanghai Institute of Applied Mathematics and Mechanics,Shanghai University

出　　处：《Journal of Hydrodynamics》2014年第1期129-136,共8页水动力学研究与进展B辑（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.11102114,11172179);the Innovation Program of Shanghai Municipal Education Commission(Grant No.13YZ124)

摘　　要：In this paper orthogonal wavelet transformations are applied to decompose experimental velocity signals in fully develo-ped channel flows with varying pressure gradient into scales. We analyze the time series from turbulent data, to obtain the statistical characteristics, correlations between the adjacent scales and the principal scale of coherent structures in different scales by wavelet transformations. The results show that, in the counter gradient transport （CGT） region, skewness factors and flatness factors deviate strongly from the corresponding values of Gaussian distribution on certain scales. PDFs on each scale confirm this observation. Scale-scale correlations show further that the fluctuations on some certain special scales are more intermittent than nearby. Principal scale of coherent structure is coincident with the scales on which the statistical properties depart from Gaussian distribution. These features are the same for different families of wavelets, and it also shows some different features in the region between favorable pressure gradient and adverse pressure gradient.In this paper orthogonal wavelet transformations are applied to decompose experimental velocity signals in fully develo-ped channel flows with varying pressure gradient into scales. We analyze the time series from turbulent data, to obtain the statistical characteristics, correlations between the adjacent scales and the principal scale of coherent structures in different scales by wavelet transformations. The results show that, in the counter gradient transport （CGT） region, skewness factors and flatness factors deviate strongly from the corresponding values of Gaussian distribution on certain scales. PDFs on each scale confirm this observation. Scale-scale correlations show further that the fluctuations on some certain special scales are more intermittent than nearby. Principal scale of coherent structure is coincident with the scales on which the statistical properties depart from Gaussian distribution. These features are the same for different families of wavelets, and it also shows some different features in the region between favorable pressure gradient and adverse pressure gradient.

关 键 词：TURBULENCE counter gradient transport （CGT） wavelet analysis pressure gradient channel flow 

分 类 号：O357.5[理学—流体力学] TE312[理学—力学]