Author(s): A. Keshavarzy; Je Ball

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Abstract: The influence of turbulence on the entrainment of sediment particles from a plane mobile bed was investigated using image processing techniques to record sediment particle motion in an experimental flume while simultaneously monitoring the turbulence characteristics of the flow. The importance of the image processing techniques applied arise from the use of the collected images for determination of the area of sediment entrained and the instantaneous particle velocity. A subtraction technique was used to derive the difference between consecutive images, from which the number of particles entrained in an increment of time could be determined. A cross correlation was applied to find if a relation between the number of entrained particles and the instantaneous shear stress in sweep events existed. A significant correlation with was found for this relation. From the results obtained, the exceedance probability of the area entrained was found to correlate with the exceedance probability of instantaneous shear stress in a sweep event. Image processing was found to be a useful technique for the analysis of experimental data and fundamental to this study aimed at investigating the entrainment mechanisms for sediment particles.

DOI: https://doi.org/10.1080/00221686.1999.9628268

Year: 1999