Two‐Point Velocity Correlations in Fully Developed Turbulent Pipe Flow at Shear Reynolds Number of Re τ  ≈ 4000

Abstract

The aim of this study is to report about the large‐scale pipe flow structures using the two‐point velocity correlations at a radial location of y/R = 0.5 and 41 azimuthal positions for shear Reynolds number Re τ  ≈ 4000. The streamwise velocity component was measured, utilizing two single‐wire probes, simultaneously, based on various azimuthal probe separations. One dimensional pre‐multiplied energy spectra, and two‐point joint statistics were adopted. Both the low and the high wavenumber motions were highlighted using the pre‐multiplied cross‐spectral density. The cross‐power spectral analysis for all the 41 measurement points indicates strong correlation between the hot‐wire signals with small azimuthal separation, on contrary, the peak of the spectrum is getting damped as the azimuthal distance increases. For present shear Reynolds number, the large and the very large scale motions showed wavelengths of ≈ 3 R and 14 R , respectively, at half of the pipe radius.