Author(s): Hélder Guta, Stefan Fischer, Damien Dufour , Marie Burckbuchler, Guillaume Fromant
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Keywords: Acoustic Concentration and Velocity Profiler; ACVP; UB-MES; turbulence measurements; sediment flux profiling
Abstract:
In the present paper, new data set of co-located 2C velocity and sediment concentration time-resolved measurements under steady uniform turbulent rough clear water and sheet-flow, performed with an Acoustic Concentration and Velocity Profiler (ACVP) and a prototype for a commercial ADVP, the UB-MES, are presented. The flow regime for the measurement with both devices was similar. Comparisons of mean profiles of fluid velocity, Reynolds shear stress and turbulence intensities showed good agreements, with a mean relative error below 10% in clear water flow conditions. Time-resolved turbulence measurements also displayed a good agreement between the systems. The quadrant threshold distribution showed that both ejections and sweeps are the dominant turbulent bursting events in clear water uniform rough flow. Good agreement was also observed in sheet-flow measurements from ACVP and UB-MES. Comparisons of mean velocity profiles, sediment concentration and sediment flux under sheet-flow, revealed relative differences below 20%. The quadrant analysis showed different dynamics from clear water flow. Sweeps seem to be the dominant events particularly in the near-bed region, followed by outward interactions. However, in the upper region of the flow, ejections and sweeps become the two dominant turbulent bursting events, as in clear water flow. The conformity with results from previous studies performed in similar flows conditions supports the good performance of the UB-MES for turbulence measurements and sediment flux profiling.
Year: 2019