The 3D structure of turbulent channels up to Re_τ=4000

Several time-resolved fluid dynamics videos of turbulent channels from $\mathrm{Re}_\tau=180$ to $\mathrm{Re}_\tau=4000$ are presented. The videos show the temporal evolution of sweeps (bluish) and ejections (reddish) in one half of the channel (only the bottom wall is shown). The color changes from dark for points close to the wall, to bright for those reaching the center of the channel. As the Reynolds number increases the scale separation becomes more clear and the complexity of the dynamics observed rises.