Many studies show that suspended sediment may substantially affect the carrier fluid turbulence in sediment-laden flows. This effect should be taken into account when modeling such flows, which is not usually done due to the incomplete knowledge of this interdependence. Another assumption that is usually made is that fluid and particles have the same hydrodynamic characteristics. This paper presents some initial results of investigations on water and suspended sediment turbulence characteristics in an open-channel flow. Two kinds of sediment were used in the investigations. Results obtained with crushed walnut shell with relative density of 1.3 and particle diameter ranging from 0.590 mm to 0.710 mm are presented here. The fluid was traced with spherical glass particles with a diameter of 0.040 mm. Velocities for particles and water were measured, simultaneously, using Particle Tracking Velocimetry (PTV). Phase separation was made using the size of the particles as phase-discrimination criterion. A self-adaptive, iterative, procedure for discarding the erroneous measurements introduced by the PTV technique was developed. For the experimental conditions investigated, the downstream and vertical turbulence intensities of the water were enhanced by the addition of the sediment. The comparison between water and sediment turbulence intensities shows that the particle turbulence intensities are lower than those for water, both in the streamwise and vertical directions
Experimental study on liquid and suspended sediment turbulence characteristics in open-channel flows.
DI CRISTO, Cristiana;
2002-01-01
Abstract
Many studies show that suspended sediment may substantially affect the carrier fluid turbulence in sediment-laden flows. This effect should be taken into account when modeling such flows, which is not usually done due to the incomplete knowledge of this interdependence. Another assumption that is usually made is that fluid and particles have the same hydrodynamic characteristics. This paper presents some initial results of investigations on water and suspended sediment turbulence characteristics in an open-channel flow. Two kinds of sediment were used in the investigations. Results obtained with crushed walnut shell with relative density of 1.3 and particle diameter ranging from 0.590 mm to 0.710 mm are presented here. The fluid was traced with spherical glass particles with a diameter of 0.040 mm. Velocities for particles and water were measured, simultaneously, using Particle Tracking Velocimetry (PTV). Phase separation was made using the size of the particles as phase-discrimination criterion. A self-adaptive, iterative, procedure for discarding the erroneous measurements introduced by the PTV technique was developed. For the experimental conditions investigated, the downstream and vertical turbulence intensities of the water were enhanced by the addition of the sediment. The comparison between water and sediment turbulence intensities shows that the particle turbulence intensities are lower than those for water, both in the streamwise and vertical directionsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
