The origin of wall-shear stress fluctuations in wall-bounded turbulence

TL;DR

This paper investigates the origins of wall shear-stress fluctuations in wall turbulence, revealing how energy dissipation at different scales is interconnected and influenced by Reynolds number, with implications for all canonical wall-bounded turbulence.

Contribution

It uncovers the scale interactions responsible for wall shear-stress fluctuations and how these interactions evolve with Reynolds number in wall turbulence.

Findings

Universal small-scale dissipation confirmed

Energy transfer from small to large scales increases with Reynolds number

Insights applicable to all canonical wall-bounded turbulence at high Reynolds numbers

Abstract

The origin of wall shear-stress fluctuations in wall turbulence was studied through energy dissipation at the wall. While confirming the universality in wall dissipation at small inner scales, the dissipation at larger scales is a consequence of near-wall scale interactions. In particular, the energy transport from the universal small to larger scale strengthens with Reynolds number due to the growing number of intermediate scales associated with the log layer. We anticipate that these insights broadly apply to all canonical wall-bounded turbulence for sufficiently high Reynolds numbers.