The streaks of wall-bounded turbulence need not be long

TL;DR

This study demonstrates through numerical experiments that long streaks in wall-bounded turbulence are not essential for the bursting process, challenging the traditional view of their role in turbulence dynamics.

Contribution

It shows that turbulence can sustain itself without long streaks, suggesting these streaks may be byproducts rather than active components of energy generation.

Findings

Long streaks are not necessary for turbulence self-sustenance.

Bursting processes can occur with streaks approximately the same length as bursts.

Long streaks may be byproducts, not active in energy generation.

Abstract

The effect of damping the longest streaks in wall-bounded turbulence is explored using numerical experiments. It is found that long streaks are not required for the self-sustenance of the bursting process, 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 burst structure is essentially indistinguishable from flows in which longer velocity fluctuations are present. This suggests that the long streaks found in unmodified flows may be byproducts, rather than active parts of the energy generation cycle.