摘要
首先利用子波(Wavelet)WTMM理论对Rayleigh-Bénard(R-B)对流温度信号的多分形特性进行了分析,然后采用本文给出的子波反演公式,不加入任何门限地提取了该信号的相干结构。在此基础上,通过对本文定义的一个非相干结构信号的分形特性研究,来反映出相干结构对多分形特性的影响。研究结果表明:代表大尺度运动的相干结构对小尺度上体现出来的多分形谱D(h)几乎没有影响,在这个意义上讲,分形谱D(h)具有不变性。
The method of Wavelet Transform Modulus Maximum (WTMM) is used to study the multi-fractal properties of temperature data in Rayleigh-Bénard convection. With wavelet transformation, the coherent structure involving temperature data is extracted. By the definition of a so called non-coherent signal (the original signal minus coherent signal), the influence of coherent structure on the multifractal spectrum D(h) and the relation between large scale motions and small ones are highlighted. It is concluded that the large scale coherent motions do not have almost any influence on D(h) which can only be seen at small scale structures. In this sense, the multifractal spectrum D(h) is invariant.
出处
《工程力学》
EI
CSCD
北大核心
2005年第3期102-106,96,共6页
Engineering Mechanics
基金
香港特别行政区研究资助局基金资助(CUHK319/96P)
