Experiments on a single large particle segregating in bedload transport - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles Physical Review Fluids Year : 2022

Experiments on a single large particle segregating in bedload transport

Abstract

We performed experiments on a large particle segregating upward in turbulent bedload transport. The experiment was conducted in a narrow flume, fed with small glass beads and water. The large particle, called the intruder, was a glass bead plunged into the bed of smaller glass beads. Its ascent was tracked using image analysis methods. We performed 11 configurations using two Shields numbers and eight size ratios ranging from 1 to 5.3. For each configuration, the experiment was repeated from five to seven times in order to evaluate its repeatability. We found that the temporal ascent of the intruder exhibited two stages. At first, the intruder rose slowly with an intermittent motion. Then, a second stage was observed in which the intruder accelerated suddenly until it reached the top of the bed. While the kinematics of the second stage was found to be repeatable for a given configuration, it was not the case for the first stage. A transition in the size ratio was also observed. For size ratio close to unity, the ascent was much more intermittent than above a size ratio r = 1.7. Above the same value, the trajectory of the intruder (vertical displacement as a function of the streamwise displacement) became linear with a constant slope, independent of the Shields number and the size ratio. Based on observations, we proposed a segregation mechanism that could explain this linear trajectory.
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Dates and versions

hal-04053589 , version 1 (31-03-2023)

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Hugo Rousseau, Julien Chauchat, Philippe Frey. Experiments on a single large particle segregating in bedload transport. Physical Review Fluids, 2022, 7 (6), pp.064305. ⟨10.1103/PhysRevFluids.7.064305⟩. ⟨hal-04053589⟩
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