Author(s): C. Shen; U. Lemmin

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Abstract: An acoustic particle flux profiler (APFP) has been used to non-intrusively and simultaneously profile the instantaneous concentration and the 2-D velocity vector in particle-laden open-channel flow. A temporal resolution of 0.04s and a spatial resolution of φ14.2x4.5mm3 have been achieved by carefully choosing the APFP parameters. The performance of the APFP has been investigated in two flows under capacity charge conditions. The measured results for the mean profiles of velocity, velocity variance, Reynolds stress, concentration, particle flux, moment flux, diffusion coefficients, etc., are compared with the theoretical or semi-empirical formulas. Good agreement has been found. The fluctuation fields of velocity and concentration are highly correlated. Two kinds of coherent structures, the ejection and the inrush, are found to be the dominant structures in the outer region which are responsible for particle entrainment, resuspension and deposition in a particle-laden flow. It is concluded that the recently developed APFP is a powerful non-intrusive instrument for sediment transport studies in open-channel flow and that it works well under capacity charge conditions where other instruments have difficulties. It provides rich information on the details of flow structures and of particle-turbulence interactions.

DOI: https://doi.org/10.1080/00221686.1999.9628256

Year: 1999