Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 54 4 2022 06 22 Probabilistic description of coarse particle motion above threshold by particle tracking velocimetry method in an experimental study Probabilistic description of coarse particle motion above threshold by particle tracking velocimetry method in an experimental study 1591 1606 4416 10.22060/ceej.2021.19759.7253 FA Hamed Farhadi Phd candidate for hydro structures, Water Science and Engineering Department, Ferdowsi University of Mashhad 0000-0003-4940-9571 Kazem Esmaili Associate Professor Department of Water Science and Engineering , Ferdowsi University of Mashhad Manousos Valyrakis Assistant professor/School of engineering, University of Glasgow, Glasgow, United Kingdom Abdolreza Zahiri Water and soil engineering faculty, Water engineering department, Gorgan university of agricultural sciences and natural resources, Gorgan, Iran Journal Article 2021 03 17 Sediment motion behavior plays an essential role in sediment and hydraulic engineering, though its physics is still not fully understood. Ignoring the stochastic nature of the sediment transport leads to various equations for bedload transport which are now being challenged due to their results. In this study, the non-suspended particle motion (bedload transport) in different hydraulic conditions was assessed by a particle tracking technique called Particle Tracking Velocimetry (PTV). The results of the PTV were applied to describe the particle behavior throughout the probability distribution functions. Knowing the particle motion behavior would guide learning more about the parameter/s governing the particle transport in different sediment transport regimes. The instantaneous particle velocity was measured after calibrating and validating the frames (resulted from the PTV). Different probability distribution functions were assessed with the Kolmogorov-Smirnov criterion (in 5 percent of the level of confidence) to find the best function which fits the collected data (i.e., the particle velocity). Furthermore, an analysis of the governing parameter for particle entrainment in different transport regimes was conducted. It was found that in a weak transport regime, the particle-bed and higher transport regime, the particle-flow interrelations were the governing factors that make the particle move. It was shown that the probability distribution function is Lognormal for lower particle Reynolds number, and on the other hand, in the higher particle Reynolds number, the Normal distribution best describes the particle velocity. The results of this research also could be applied in similar hydraulic conditions in the eco-hydraulic field, specifically macro-plastic movement as bedload in river courses and Aeolian research.  Sediment motion behavior plays an essential role in sediment and hydraulic engineering, though its physics is still not fully understood. Ignoring the stochastic nature of the sediment transport leads to various equations for bedload transport which are now being challenged due to their results. In this study, the non-suspended particle motion (bedload transport) in different hydraulic conditions was assessed by a particle tracking technique called Particle Tracking Velocimetry (PTV). The results of the PTV were applied to describe the particle behavior throughout the probability distribution functions. Knowing the particle motion behavior would guide learning more about the parameter/s governing the particle transport in different sediment transport regimes. The instantaneous particle velocity was measured after calibrating and validating the frames (resulted from the PTV). Different probability distribution functions were assessed with the Kolmogorov-Smirnov criterion (in 5 percent of the level of confidence) to find the best function which fits the collected data (i.e., the particle velocity). Furthermore, an analysis of the governing parameter for particle entrainment in different transport regimes was conducted. It was found that in a weak transport regime, the particle-bed and higher transport regime, the particle-flow interrelations were the governing factors that make the particle move. It was shown that the probability distribution function is Lognormal for lower particle Reynolds number, and on the other hand, in the higher particle Reynolds number, the Normal distribution best describes the particle velocity. The results of this research also could be applied in similar hydraulic conditions in the eco-hydraulic field, specifically macro-plastic movement as bedload in river courses and Aeolian research.  https://ceej.aut.ac.ir/article_4416_1da546f25222c1ee710cf7e2f7a3ff0c.pdf