Two-point correlations for zero-pressure-gradient turbulent boundary layers and channels at $Re_\tau \approx 1000-2000$

Two-point 5-dimensional correlations $C_{\xi\xi}(x; x'; y; y'; \Delta z)$ are investigated to educe the structure of the velocity and pressure fluctuations in zero-pressure-gradient turbulent boundary layers in the range $Re_\theta = 2780-6680$, and in matching channels at $Re_\tau \approx 1000-2000$. Eddies in channels are coherent over longer distances than in boundary layers, especially for $C_{uu}$ in the direction of the flow. At the 5\% level, the maximum streamwise length of $C_{uu}$ is $O(6\delta)$ for boundary layers and $O(15h)$ for channels. The corresponding lengths for the transverse velocities and for the pressure are shorter, $O(\delta\mbox{-}2\delta)$, and of the same order for both flows. Integral correlation lengths in the streamwise and spanwise directions grow away from the wall, except for $L_{uu,x}$, which peaks at $y\approx 0.6h$ in channels and at $y\approx 0.2 \delta$ in boundary layers, probably due to the outer intermittency in the latter. Above the buffer layer, $C_{uu}$ is inclined by $\approx 10-12^o$ from the wall, the wall-normal velocity and the pressure are roughly vertical, and $C_{ww}$ is inclined by $\approx 30^o$. Those features seem unaffected by the Reynolds number and by the type of flow.