The current work presents an experimental investigation of interactions between flow scales. Injecting a single Fourier mode into a round jet flow made it possible to isolate and analyze the generation process of the high spectral components along the downstream flow development and to measure when they eventually are absorbed into the fully developed turbulence. Furthermore, an interesting dynamic evolution of the measured power spectra has been observed that confirms the cascaded delays reported by Josserand et al. 2017. Lately, these cascade delays have also been derived directly from a one-dimensional interpretation of Navier-Stokes equations described in a companion paper. The results in the current work provide vital information about the time scales in the triad interaction process.

We combine extended proper orthogonal decomposition (EPOD) together with the Fukagata-Iwamoto-Kasagi (FIK) identity to quantify the role of individual coherent structures on the wall mass transfer in a turbulent pipe flow. Direct numerical simulation (DNS) at a Reynolds number of 5300 (based on bulk velocity) is performed with the passive scalar released at the pipe inlet. The proper orthogonal decomposition (POD) eigenvalues show that the scalar field can be described by a more compact set of modes compared to the velocity field, and that these modes are skewed towards

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The fully developed round turbulent jet has been extensively studied, whereas the developing region is much less understood. The high shear and turbulence intensities in the most interesting parts of the developing region make them inaccessible to common measurement techniques such as Constant Temperature Anemometry (CTA) due to the high demands on the measurement techniques for accuracy of the measurements. Turbulence measurements are therefore planned using our in-house laser Doppler anemometer (LDA) system based on its capability to provide accurate measurements and with its inherent ability to properly distinguish velocity components.   A rigorous measurement with the intended LDA system however demands impractical processing time, so knowing the critical points at which measurement are to be taken will save valuable time. This information is herein acquired significantly faster and more practically, however less accurately, with single-wire CTA. A high-resolution measurement was done using a computer-controlled single-wire CTA with the wire probe mounted perpendicular to the incoming flow from the jet orifice. The measurements covered several points in the radial (r-direction) along x/D=10, x/D=15, x/D=20 and x/D=30 downstream (where D is the jet exit diameter), with spatial resolutions ranging from 1 to 3 mm between the points, depending on how far the measurement was from the jet centerline. A proper alignment was also conducted prior to measurement so that the same points can be reached again for LDA measurement on the same jet afterwards. The radial profiles of mean velocity and turbulence intensity at each downstream position are presented to show the statistics of the air flow inside and outside the jet. As expected from theory, the mean profiles display a nearly Gaussian shape, spread out and tapered with the downstream direction. The highest velocities are located at the centerline.