We simultaneously measured the flow field and wall shear stress in a straight pipe and behind an orifice by means of particle image velocimetry (PIV) and the limiting diffusion current technique (LDCT), respectively[1]. The spatio-temporal correlation coefficients of the local vertical velocity and the shear stress fluctuations are presented, and the canonical correlations between the proper orthogonal decomposition (POD) spatial eigenmodes in the recirculation region and the wall shear stress are also discussed[2]. A response time lag occurs between the wall shear stress and the velocity field. The large canonical correlation between the POD eigenmodes and wall shear stress suggests that large-scale flow structures are important for the shear stress fluctuation. These analyses are applied to the shear flow in channel and large scale motions are studied in relation with the shear stress fluctuations.
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机译：我们同时通过粒子图像速度（PIV）和限制扩散电流技术（LDCT）在直线管和孔口后面测量流场和壁剪切应力[1]。介绍了局部垂直速度和剪切应力波动的时空相关系数，并且还讨论了再循环区域和壁剪切应力中的适当正交分解（POD）空间特征模码之间的规范相关性[2]。在壁剪切应力和速度场之间发生响应时间滞后。 Pod Eigenmodes和壁剪切应力之间的大规范相关性表明，大规模的流动结构对于剪切应力波动是重要的。这些分析应用于通道中的剪切流程，并在剪切应力波动方面研究了大规模的运动。
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