Streamwise inclination angle of wall-attached eddies in turbulent channel flows

We develop a new methodology to assess the streamwise inclination angles (SIAs) of wall-attached eddies populating logarithmic region with given wall-normal height. To remove influences originating from other scales on SIA estimated via two-point correlation, footprints targeted in vicinity wall and corresponding velocity fluctuations carried by them are isolated simultaneously, coupling spectral stochastic estimation attached-eddy hypothesis. Datasets produced direct numerical simulations spanning $Re_{\tau } \sim O(10^2)\unicode{x2013}O(10^3)$ dissected study Reynolds number effect. The present results show, for first time, that SIAs attached Reynolds-number-dependent low medium numbers, tend saturate at $45^{\circ }$ as increases. mean reported vast previous experimental studies demonstrated be outcomes additive effect contributed multi-scale eddies. These findings clarify long-term debate perfect picture model.