用子波变换检测壁湍流信号局部标度指数

本文用子波变换检测了刻画壁湍流脉动信号自相似性的局部标度指数，研究了不同尺度的湍流结构的自相似性，发现在湍流边界层猝发过程中，喷射和扫掠发生时刻小尺度脉动速度信号的局部标度指数为负值，说明在大尺度猝发事件发生的时刻小尺度结构具有奇异的自相似性，在猝发过程中其作用不仅仅是对湍能的耗散．

Measuring the Local Scaling Exponent in Wall Turbulence by Using Wavelet Transform

Wavelet transform is introduced to measure the local scaling exponent which characterizes the local self similarity of fluctuating velocity in wall turbulence, and than the self similarity of the turbulence structures on different scales is examined. It is found that in the process of burst event, while ejections and sweeps occure in a turbulent boundary layer, the local scaling exponent is negative. The fact shows that while large scale burst events take place, the small scale structures may have singular self similarity, and their roles are not only to dissipate the turbulent energy.