The scaling universality of structure functions is studied for artificially thickened turbulent boundary-layer flows in over-tripped impacts by using hot-wire measurement datasets. The self-similarity behaviours in the inner and outer regions are examined from the viewpoint of different flow mechanisms. In the inner region, the relative ratios between structure functions for the energy-containing range of scales exhibit universality behaviour, in accordance with Townsend's attached eddy hypothesis. This universality of the energy-containing range of scales extends further away from the wall by increasing the tripping intensity. On the other hand, the impact of the external intermittency on the self-similarity of small-scale turbulence is examined through the intermittent zone in over-tripped conditions. Towards the boundary-layer edge, the structure functions exhibit a growing departure from self-similarity and analytical prediction, and it is demonstrated that the departure is primarily due to external intermittency. Moreover, based on the conditional statistics concentrated in the turbulent regimes, it is revealed that the small scales in the turbulence regime are homogenized in a self-similar behaviour, which is independent of the current tripping conditions.

中文翻译：

---

过度湍流边界层流中的自相似性

通过使用热线测量数据集，研究了过度撞击中人工增厚的湍流边界层流的结构函数的标度普适性。从不同流动机制的角度检查内部和外部区域的自相似行为。在内部区域，包含能量的尺度范围的结构函数之间的相对比率表现出普遍性行为，符合汤森附加涡流假说。通过增加触发强度，尺度含能范围的这种普遍性可以进一步远离墙壁。另一方面，通过超跳条件下的间歇区考察了外部间歇性对小尺度湍流自相似性的影响。朝向边界层边缘，结构函数表现出越来越偏离自相似性和解析预测，并且证明这种偏离主要是由于外部间歇性造成的。此外，基于集中在湍流区域的条件统计，表明湍流区域中的小尺度在自相似行为中是均匀的，这与当前的跳闸条件无关。