基于小波分析后台阶流动中的湍动能能谱分布

Turbulent Energy Spectra Distribution in Backward Step Facing Flow Based on Wavelet Analysis

利用小波分析良好的时频双局域性特点,对准周期性非定常流场的速度信号进行了多辨析研究.使用大涡模拟方法得到了后台阶流动的流场,借助正交离散小波变换将流场中各处的速度信号在不同频带上逐层分解.提出了以特征频带名义频率和特征频带速度幅值作为描述流场各点处湍动能在不同频带上能谱分布的量化指标的新方法.以分析后台阶流动的脉动速度场为例,结果表明,所提出的方法可以为改进大涡模拟方法中的网格分布提供理论依据.

Wavelet analysis has an excellent hi-locality function in both time and frequency filed. When applied to analyze unsteady signal, it can bring more information than traditional Fourier analysis. By using the orthogonal discrete wavelet transformation, the unsteady velocity signals at each spatial location from the large eddy simulation of a backward step facing flow was decomposed into a series of orthogonal frequency bands. Based on wavelet multi-resolution analysis, a reasonable method is put forward here to describe turbulent energy distribution over frequency bands at each spatial location, where characteristic band frequency and characteristic band velocity amplitude was established as the analysis indicators. The research has led to the conclusion that grid distribution quality in the large eddy simulation will be promoted by using the method in this paper.