Progress in Wall Turbulence 2 pp 335-346 | Cite as

# Large-Scale Organization of a Near-Wall Turbulent Boundary Layer

## Abstract

Large-scale streaky structures play an important role in the turbulence production process of a boundary layer. Adrian has proposed a model at very large scales which could explain the organization of the boundary layer, but at high Reynolds number, their main characteristics (size, intensity and life time) and the way they interact with the near-wall structures is still not fully understood. To tackle these points, an experimental database at a Reynolds number based on momentum thickness \(Re_{\theta }\) close to 9800 was recorded in the Laboratoire de Mécanique de Lille wind tunnel with stereo-PIV (SPIV) and hot-wire anemometry (HWA). With a Linear Stochastic Estimation (LSE) procedure based on correlations computation, a three-component velocity field was reconstructed at high frequency from stereo-PIV at 4 Hz and hot-wire data at 30 kHz. To extract large streaky structures, a threshold is applied to normalized streamwise velocity fluctuations from the reconstructed PIV field, and then 3D morphological operations (erosion and dilatation) are combined with a volume-size-based cleaning procedure to remove the noise and smooth the object boundaries. Some statistical characteristics of the large streaks are obtained.

## Keywords

Root Mean Square Reynolds Stress Free Stream Velocity Streaky Structure Streamwise Velocity Fluctuation## References

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