Experimental observations of particle-particle interactions in settling velocity of polidispersed sediment mixtures [Observaciones experimentales de las interacciones entre partículas en la velocidad de caída de mezclas polidispersas de sedimentos]

Experiments with non-uniform sediment mixtures were developed in a suspended sediment transport channel of 22m long and cross section of 1.2x1 m. Using image analysis the settling velocities for different particle diameters of the polidisperse mixture were calculated. The Particle Tracking Velocimetry (PTV) method was used, The Images of particles illuminated by laser light were captured using the software Looksee. Particle identification and displacement was made using the software AIP that uses analysis by integrated processing. The results show that the settling velocities of small diameter are affected by the presence of larger diameter particles. Physical explanation of the phenomena is related with the changes in turbulent characteristics of the fluid by the larger particles