Logarithmic energy profile of the streamwise velocity for wall-attached eddies along the spanwise direction in turbulent boundary layer

The present work explores the spanwise logarithmic decay of the turbulence intensity for wall-attached eddies per Townsend's attached eddy hypothesis. Within the dataset spanning a friction Reynolds number range R e tau similar to O ( 10 3 ) - O ( 10 6 ), the coherence between the turbulence in the logarithmic region along the spanwise direction and that at a near-wall reference location is used to assess the scale-dependent coherence. Linear coherence spectrum analysis is applied as a filter to separate the coherent and incoherent portions. After this separation procedure, the turbulence intensity decay for wall-attached eddies in the spanwise direction is described in a log-linear manner, which also identifies how the scaling parameter increases with the Reynolds number. This variation is parametrized and consequently can be used to improve existing near-wall models.

Automated summary

This study investigates the logarithmic decay of turbulence intensity for wall-attached eddies in the spanwise direction, using linear coherence spectrum analysis to separate the coherent and incoherent portions. It identifies how the turbulence intensity scaling parameter increases with the Reynolds number, and provides a parameterization that can be used to enhance existing near-wall models.