Wall-bounded turbulence does not need streaks

The streaks of wall-bounded turbulence are typically much longer than the bursts of the cross-plane velocities. Here, the effect of damping long streaks is explored using numerical experiments, and it is shown that they are not required for the self-sustenance of the bursting, which is relatively little affected by their absence. In particular, there are turbulence states in which the fluctuations of the streamwise velocity have approximately the same length as the bursts, and are thus presumably associated with the bursts themselves, while the bursts are essentially indistinguishable from flows in which longer velocity fluctuations are present. This suggests that the long streaks found in natural wall-bounded turbulence may be by-products, rather than active parts of the turbulence regeneration process.