Large-scale spanwise periodicity in a canonical turbulent boundary layer

Abstract

The present study reports empirical evidence for periodic organization of very large-scale motions (also known as superstructures), along the spanwise direction, in a zero pressure gradient turbulent boundary layer. This is made possible by performing a scale-specific coherence analysis on datasets comprising streamwise velocity fluctuations, synchronously measured at multiple locations across large spanwise and wall-normal separations within the shear flow. Datasets considered include published low-Ret direct numerical simulation and high-Ret experimental datasets across a friction Reynolds number range, Ret ~ O(103) – O(104). The present analysis supports the notion on the superstructures ..