论文标题
湍流通道流中壁式涡流的流向倾斜角
Streamwise inclination angle of wall-attached eddies in turbulent channel flows
论文作者
论文摘要
我们开发了一种新方法，以评估壁式涡流的流向倾斜角（SIA），该涡流填充了以给定的壁正常高度的对数区域。为了消除源自通过两点相关估计的SIA的其他量表的影响，通过将它们携带的靶向涡流和相应的流向速度波动与附件估计与附着的Eddy假说耦合。剖析了$re_τ\ sim o（10^2）-o（10^3）$的直接数值模拟生成的数据集，以研究雷诺数数量的效果。目前的结果首次表明，随着雷诺数的增加，附着的涡流的SIA是雷诺数依赖的雷诺数依赖于雷诺数和中等雷诺数，并且倾向于以$ 45^{\ circ} $饱和。大量先前的实验研究报告的平均SIA被证明是由多尺度附着的涡流造成的添加效应的结果。这些发现阐明了长期的辩论，并完善了附件模型的图片。
We develop a new methodology to assess the streamwise inclination angles (SIAs) of the wall-attached eddies populating the logarithmic region with a given wall-normal height. To remove the influences originating from other scales on the SIA estimated via two-point correlation, the footprints of the targeted eddies in the vicinity of the wall and the corresponding streamwise velocity fluctuations carried by them are isolated simultaneously, by coupling the spectral stochastic estimation with the attached-eddy hypothesis. Datasets produced with direct numerical simulations spanning $Re_τ \sim O(10^2)-O(10^3)$ are dissected to study the Reynolds-number effect. The present results show, for the first time, that the SIAs of attached eddies are Reynolds-number dependent in low and medium Reynolds numbers and tend to saturate at $45^{\circ}$ as the Reynolds number increases. The mean SIA reported by vast previous experimental studies are demonstrated to be the outcomes of the additive effect contributed by multi-scale attached eddies. These findings clarify the long-term debate and perfect the picture of the attached-eddy model.
