用局部平均速度结构函数检测湍流边界层多尺度相干结构

测量风洞中平板湍流边界层不同法向位置的流向速度时间序列信号，提出了基于局部多尺度平均意义的湍流多尺度局部平均结构函数的概念，以描述湍流多尺度结构的伸缩变形和相对运动；基于多尺度局部平均结构函数的概念与Harr子波变换的一致性，提出了用湍流多尺度局部平均结构函数的平坦因子检测湍流边界层多尺度相干结构及其间歇性的检测方法，提取近壁区域不同法向位置处多尺度相干结构的条件相位平均波形，以研究多尺度相干结构猝发的动力学过程及其对湍流统计性质的影响．

Multi-Scale Coherent Structures in Turbulent Boundary Layer Detected by Locally Averaged Velocity Structure Functions

The time sequence of longitudinal velocity component at different vertical locations in turbulent boundary layer was finely measured in a wind tunnel. The concept of coarse_grained velocity structure functions, which describes the relative motions of straining and compressing for multi_scale eddy structures in turbulent flows, was put forward based on the theory of locally multi_scale average. Based on the consistency between coarse_grained velocity structure function and Harr wavelet transformation,detecting method was presented, by which the coherent structures and their intermittency was identified by multi_scale flatness factor calculated by locally average structure function. Phase_averaged evolution course for multi_scale coherent eddy structures in wall turbulence were extracted by this conditional sampling to educe scheme. The dynamics course of multi_scale coherent eddy structures and their effects on statistics of turbulent flows were studied.