【摘要】 认为相干结构是具有一定脉动强度的大尺度结构.通过正交离散小波变换,在离散小波系数的基础上,定义小波系数的间歇性系数,设定间歇性系数阀值,阀值以上的小波系数参与信号的重构,阀值以下的小波系数赋零处理(相当于过滤小脉动).认为相干结构是强脉动占主导,小脉动的成分最小,小脉动的能量也最小,提出能量比最小准则确定相干结构的尺度.更多还原

【Abstract】 The coherent structure in turbulence is considered as large-scale structure with certainly intense fluctuation.Through the orthogonal discrete wavelet transformation,we get the discrete wavelet coefficients and use them to define the intermittency coefficients.A threshold of intermittency coefficients is suggested to choose the corresponding wavelet coefficients that will be used to reconstruct the signal,while the wavelet coefficients below the threshold are endowed with zero values.Therefore,the intense fluctuations dominate the coherent structure and the small-scale fluctuations have minimal energy.This character can be applied to determine the characteristic scale of coherent structure,and is called the minimal energy ratio principle.更多还原