雷诺应力各向异性涡黏模型的层析TRPIV测量

利用层析TRPIV测量水洞中平板湍流边界层3D-3C速度场的高分辨率时间序列数据库. 提出了空间局部平均多尺度速度结构函数的新概念, 描述湍流多尺度涡结构的空间拉伸、压缩、剪切变形和旋转. 用空间局部平均多尺度速度结构函数对湍流脉动速度进行了空间多尺度分解. 用空间流向局部平均多尺度速度结构函数, 根据湍流多尺度涡结构在流向的拉伸和压缩物理特征, 提出了新的湍流相干结构条件采样方法, 检测并提取了层析TRPIV数据中相干结构“喷射”和“扫掠”事件中的脉动速度、平均速度变形率、雷诺应力等物理量的空间拓扑形态. 通过研究平均速度变形率各分量与雷诺应力各分量之间的空间相位差异,肯定了壁湍流相干结构雷诺应力各向异性复涡黏模型的合理性.

TOMOGRAPHIC TRPIV MEASUREMENT OF ANISOTROPIC EDDY-VISCOSITY MODEL FOR COHERENT STRUCTURE REYNOLDS STRESS

The time sequences dataset of 3D-3C flow field of turbulent boundary layer in a water tunnel by tomographic TRPIV were employed to put forward the new concept of spatial locally-averaged velocity structure function of turbulence that describes the spacial dilation,compression,shear deformation and rotation of the multi-scale turbulent eddy structure.According to the physical characteristics of the multi-scale vortex structures’ stretch and compression in turbulent flow,a new conditional sampling method of coherent structure, based on the concept of multi-scale spatial locally averaged velocity structure function along the longitudinal direction,was proposed to extract the spatial topology of physical quantities such as fluctuating velocity,mean velocity strain rate and Reynolds stress during the process of coherent structure burst in TRPIV dataset.In this paper,the relationship between mean velocity strain rate and Reynolds stress was studied.The validity of the anisotropic eddy viscosity model was confirmed for coherent structure Reynolds stress in wall-bounded turbulence through investigating the spatial phase difference between Reynolds stress components and mean velocity strain rate components.