Scale dependence of Reynolds stress transport in wall-bounded turbulence at $Re_\tau= 5200$

A direct numerical simulation (DNS) of turbulent channel flow has been performed to study high Reynolds number wall-bounded turbulence. In particular, in this talk we will focus on the characteristics of the terms in the Reynolds stress transport equations in two recent channel flow DNS at $Re_\tau=1000$ and $5200$. The $Re_\tau=5200$ case is at sufficiently high Reynolds number for there to be a significant scale separation between the near-wall and outer layer turbulence. A spectral analysis of the Reynolds stress transport terms shows how the inner- and outer-layer turbulence interact across scale. One striking result of this analysis is that over a broad range of $y$, the turbulent transport of turbulent kinetic energy occurs at scales that are proportional to $y$. There is also a weak direct interaction between the outer-layer and near-wall turbulence at large scales, presumably resulting in the large-scale modulation of near-wall turbulence. Further results from this spectral Reynolds stress transport analysis will be presented to explore the characteristics of turbulent, viscous and pressure effects.