Direct measurement of the inertial drag and lift forces on entrained coarse particles at various protrusion heights

Xie, Yushu; Melville, Bruce W.; Shamseldin, Asaad Y.; Whittaker, Colin; Yang, Yifan

doi:10.1002/esp.5491

Cited by 3 publications

(2 citation statements)

References 53 publications

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“…Pro+ could also be used to mechanistically explain some of the observed τ c50 * variability between rivers. Protrusion is a dominant control on driving forces, resisting forces and τ c * (Hodge et al, 2020; Kirchner et al, 1990; Schmeeckle et al, 2007; Smith et al, 2023; Xie et al, 2023; Yager, Schmeeckle, & Badoux, 2018), and Pro+ explicitly includes these effects. Similarly, Pro+ could be used to explain the large measured variability in hiding function exponents, which are likely partly controlled by bed GSD (Shvidchenko et al, 2001) and protrusion.…”

Section: Discussionmentioning

confidence: 99%

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

Yager,

Shim,

Hodge

et al. 2024

Earth Surf Processes Landf

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The dimensionless critical shear stress (τ*c) needed for the onset of sediment motion is important for a range of studies from river restoration projects to landscape evolution calculations. Many studies simply assume a τ*c value within the large range of scatter observed in gravel‐bedded rivers because direct field estimates are difficult to obtain. Informed choices of reach‐scale τ*c values could instead be obtained from force balance calculations that include particle‐scale bed structure and flow conditions. Particle‐scale bed structure is also difficult to measure, precluding wide adoption of such force‐balance τ*c values. Recent studies have demonstrated that bed grain size distributions (GSD) can be determined from detailed point clouds (e.g. using G3Point open‐source software). We build on these point cloud methods to introduce Pro+, software that estimates particle‐scale protrusion distributions and τ*c for each grain size and for the entire bed using a force‐balance model. We validated G3Point and Pro+ using two laboratory flume experiments with different grain size distributions and bed topographies. Commonly used definitions of protrusion may not produce representative τ*c distributions, and Pro+ includes new protrusion definitions to better include flow and bed structure influences on particle mobility. The combined G3Point/Pro+ provided accurate grain size, protrusion and τ*c distributions with simple GSD calibration. The largest source of error in protrusion and τ*c distributions were from incorrect grain boundaries and grain locations in G3Point, and calibration of grain software beyond comparing GSD is likely needed. Pro+ can be coupled with grain identifying software and relatively easily obtainable data to provide informed estimates of τ*c. These could replace arbitrary choices of τ*c and potentially improve channel stability and sediment transport estimates.

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Section: Discussionmentioning

confidence: 99%

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

Yager,

Shim,

Hodge

et al. 2024

Earth Surf Processes Landf

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“…In recent years, due to the rapid development of sensor technology, monitoring of sediment movement processes has become possible [23][24][25][26][27][28][29][30]. In 2010, Akeila [23] proposed the idea of making smart pebbles using acceleration sensors and gyroscopes, whose smart pebbles can collect data on velocity, position, kinetic energy and other indicators.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigations on the Response of Bedload Sediment to Vibration

Yuan

Wang

et al. 2023

Sustainability

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Research results on sediment vibration characteristics are scarce, and knowledge on the effect of the particle size on the sediment vibration response is still limited. In this study, natural pebbles of different heights—A, B and C—were selected (hA < hB < hC). Miniature acceleration sensors were installed inside the pebble. Experimental methods were used to measure the vibration process of pebbles on the rough bed surface and to measure the near-bed velocities simultaneously. The test results show that the sequence of pebble vibration and entrainment is A-C-B as the flow rate increases. The vibration intensity of pebbles A and B tended to increase before approaching the entrainment threshold but weakened when approaching the entrainment threshold; the vibration frequency, on the contrary, first decreased and then increased. The vibration intensity of pebble C decreased first and then increased, and when approaching the entrainment threshold, it rolled directly. The vibration frequency first increased and then decreased, and near the entrainment threshold, there was no vibration. Thus, it was demonstrated that with the increase in pebble height, the average vibration intensity increases, and the average vibration frequency decreases. The results of this research provide a reference for exploring the dynamic mechanism of the bed load in mountain rivers.

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Experiments on kinematic characteristics and energy dissipation in rockfall movement on a slope

Peng,

Chen,

Hassan

et al. 2024

Physics of Fluids

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This paper presents an experimental methodology for tracking trajectories of rockfall-saltation and extracting kinematic parameters from collisions between rockfalls and a slope surface. We conducted a series of experiments, each featuring different initial impact angles. Rockfall trajectories and their three-dimensional angular velocities were measured by a high-speed camera and built-in Inertial Measurement Unit (IMU), respectively. Our experiments demonstrate that rockfall dissipates its total energy as it progresses along the slope, and the dissipation rates are largely determined by the initial impact angle. Following the classification of rockfall-bed collisions into two modes—Mode-1: saltation dominant and Mode-2: rolling and sliding dominant, we examined the correlations between impact angles and the probability density functions of kinetic, linear, and rotational kinetic energy, as well as the coefficients of kinetic friction and restitution in both modes. Our findings highlight the crucial role of three-dimensional angular velocities in rockfall kinematics, displaying a notable divergence of up to 60% when compared with their two-dimensional counterparts. This is particularly evident in Mode-2, where the increase in rotational energy following collisions exceeds that of Mode-1 × 25%. The experimental investigation contributes to a deeper understanding of the fundamental physical processes inherent in successive rockfall-slope collisions, thereby benefitting predictive capabilities for rockfall disasters in mountainous regions.

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Direct measurement of the inertial drag and lift forces on entrained coarse particles at various protrusion heights

Cited by 3 publications

References 53 publications

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

Experimental Investigations on the Response of Bedload Sediment to Vibration

Experiments on kinematic characteristics and energy dissipation in rockfall movement on a slope

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