length-scales and generating non-Gaussian statistics of velocity increments. The statistical properties of these turbulent fluctuations are fundamentally changed when the flow is confined by the presence of solid walls or boundaries [@smits2013wall; @jimenez2013near]. In contrast to bulk turbulence, which is statistically homogeneous and isotropic, the wall-bounded turbulence is characterised by statistically anisotropic properties. Namely, there is a net mean-flow in the streamwise direction along the wall and the different flow structures form depending on their distance to the wall. We typically differentiate between four flow regions as moving away from the wall [@Ob97]: i) the [*viscous region*]{} closest to the wall and where viscous flows dominate, ii) the [*buffer layer*]{}, marking the transition from the viscous layer into the inertial layer, iii) the [*inertial layer*]{} where the log-law of the wall applies, and iv) the [*wake*]{}, the energetic region beyond the inertial layer. A more refined division is given in [@CHS19].

A classical signature of wall-bounded turbulence is the “log-law of the wall” of the mean velocity profile (MVP) due to Prandtl and von Kármán, and reads as $$\label{eq:l-lwall}
\langle \tilde u \rangle = \frac{1}{\kappa} \log(\tilde y)+B,$$ where $\kappa$ is the *universal* von Kármán constant that is independent of the 