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PIV and PTV Experimental Observations of Sediment Motion Initiation

Author(s): Garcia Aragon; J. A.; K. Izquierdo Ayala; Salinas Tapia; H. Centro

Linked Author(s): A.J. (Andries) Paarlberg

Keywords: Motion initiation; Sediment; PIV; PTV; Turbulence; Vorticity

Abstract: In order to describe the mechanisms of motion initiation, Particle Image Velocimetry (PIV) with fluorescent tracer particles and Particle Tracking velocimetry (PTV) has been used to measure the fluid and solid velocity fields above plane beds of uniform and non uniform sediments. Fluid velocities were used to find distributions of vorticity and turbulence intensity. Vortices that develop in the solid-fluid interface and are advected by the flow play a major role in the conditions of incipient motion. Particle velocities were used to define the state of motion. Most classical theories and experimental results for incipient motion of sediments consider uniform beds and neglect the effect of turbulence on sediment motion. This paper focuses in the effect of turbulence intensity and related vorticity in the mechanisms of sediment motion initiation. A comparison of classic experimental results for motion initiation velocities and the PIV and PTV results is made. Preliminary results show that those data are similar of the results of this research for low turbulent flows but differ slightly when turbulent intensity increases. In the case of non uniform sediments, grain size distribution plays a major role in sediment motion. Experiments are in progress to show the relationship between grain size distribution, turbulent intensity and motion initiation.


Year: 2005

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