scholarly journals Validation of an Experimental Procedure to Determine Bedload Transport Rates in Steep Channels with Coarse Sediment

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 672
Author(s):  
Veronica Carrillo ◽  
John Petrie ◽  
Luis Timbe ◽  
Esteban Pacheco ◽  
Washington Astudillo ◽  
...  
Keyword(s):  
Transport Model ◽  
Bedload Transport ◽  
Experimental Results ◽  
Experimental Procedure ◽  
Coarse Sediment ◽  
Sediment Size ◽  
High Gradients ◽  
Sediment Particles ◽  
Bedload Sediment ◽  
Steep Slopes

The current study presents an experimental procedure used to determine bedload sediment transport rates in channels with high gradients and coarse sediment. With the aim to validate the procedure for further investigations, laboratory experiments were performed to calculate bedload transport rates. The experiments were performed in a laboratory tilting flume with slopes ranging from 3% to 5%. The sediment particles were uniform in shape (spheres). The experiments were divided into four cases based on sediment size. Three cases of uniform sizes of 10 mm, 15 mm and 25 mm and a case with a grain size distribution formed with the uniform particle sizes were considered. From the experimental results a mathematical bedload transport model was obtained through multiple linear regression. The experimental model was compared with equations presented in the literature obtained for gravel bed rivers. The experimental results agree with some of the models presented in the literature. The closest agreement was seen with models developed for steep slopes especially for the highest slopes considered in the present study. Therefore, it can be concluded that the methodology used can be replicated for the study of bedload transport rates of channels with high gradients and coarse sediment particles to study more general cases of this process such as sediments with non-uniform shapes and sizes. However, a simplified model is proposed to estimate bedload transport rates for slopes up to 5%.

A one-dimensional bedload transport model for steep slopes

2010 ◽  
Vol 48 (2) ◽  
pp. 152-160 ◽  
Author(s):  
Michael Chiari ◽  
Kurt Friedl ◽  
Dieter Rickenmann
Keyword(s):  
Transport Model ◽  
Bedload Transport ◽  
One Dimensional ◽  
Steep Slopes

scholarly journals ON THE CHOICE OF RANDOM WAVE SIMULATION IN THE SURF ZONE PROCESSES

2011 ◽  
Vol 1 (32) ◽  
pp. 71
Author(s):  
Jing Yuan ◽  
Ole S. Madsen
Keyword(s):  
Surf Zone ◽  
Transport Model ◽  
Bedload Transport ◽  
Random Wave ◽  
Spectral Approach ◽  
Wave Approach ◽  
Bedload Sediment ◽  
Set Up ◽  
Wave Nonlinearity ◽  
Wave Induced

In this paper, the two common approaches to account for wave randomness, the spectral approach and the wave-by-wave approach, are compared through numerical experiments conducted with the coupling of a surf zone hydrodynamic model and a bedload sediment transport model. Special attention is paid to the wave nonlinearity and net cross-shore bedload transport predictions. The two approaches are found to have negligible difference in their predictions of certain average hydrodynamics, such as wave heights, set-up and undertow. However, the wave-by-wave approach outperforms the spectral approach in the wave nonlinearity prediction, and the two approaches differ significantly in their predictions of wave-induced net cross-shore bedload transport which strongly depends on wave nonlinearity. This suggests the necessity of using the wave-by-wave approach. The computational efficiency of the wave-by-wave approach is also discussed.

Numerical modelling of particle-fluid interaction in fluvial sediment transport

2020 ◽  
Author(s):  
Gaston Latessa ◽  
Dong Xu ◽  
Chunning Ji ◽  
Manousos Valyrakis
Keyword(s):  
Sediment Transport ◽  
Flow Field ◽  
Turbulent Flows ◽  
River Flow ◽  
Bedload Transport ◽  
Momentum Exchange ◽  
International Conference ◽  
Fluvial Hydraulics ◽  
Coarse Sediment ◽  
Sediment Particles

<p>Numerical simulations for the transport of coarse sediment particles in turbulent flows are performed, with particular emphasis on the energy and momentum exchange [1, 2, 3] between the two phases at the particle scale.  The solid particles positions and velocities are solved through the Discrete Element Method (DEM), coupled with a Computational Fluid Dynamics (CFD) model which updates the dynamically evolving flow field through the numerical solution of the Reynolds Averaged of Navier-Stokes equations (RANS).</p><p>At the core of this work, the coupling of these two models (DEM-CFD) based on the Fictitious Boundary Method, is analysed. The models have a high mesh resolution, by adopting a meshing strategy which aims at sufficiently discretising the flow field surrounding each particle. Smooth and rough bed cases are simulated, under a wide range of Reynolds numbers covering applications from particle entrainment, up to bulk bedload transport through rolling and saltation. The numerical results are benchmarked against experimental data obtained from controlled laboratory experiments [4, 5, 6].</p><p>The implementation of coupled CFD-DEM models provides a very powerful tool for improving the understanding of fluid and particle physics in sediment transport. Particularly, the potential to perform a large number of validated numerical that robustly predict geomorphological changes in aquatic environments and fluvial systems.</p><p><strong>References</strong></p><p>[1] Valyrakis M., P. Diplas, C.L. Dancey, and A.O. Celik. 2008. Investigation of evolution of gravel river bed microforms using a simplified Discrete Particle Model, International Conference on Fluvial Hydraulics River Flow 2008, Ismir, Turkey, 03-05 September 2008, 10p.</p><p>[2] Valyrakis M., Diplas P. and Dancey C.L. 2013. Entrainment of coarse particles in turbulent flows: An energy approach. J. Geophys. Res. Earth Surf., Vol. 118, No. 1., pp 42- 53, doi:340210.1029/2012JF002354.</p><p>[3] Pähtz, Th., Clark, A., Duran, O., Valyrakis, M. 2019. The physics of sediment transport initiation, cessation and entrainment across aeolian and fluvial environments, Reviews of Gephysics, https://doi.org/10.1029/2019RG000679.</p><p>[4] Valyrakis, M. & Pavlovskis, E. 2014. "Smart pebble” design for environmental monitoring applications, In Proceedings of the 11th International Conference on Hydroinformatics, Hamburg, Germany.</p><p>[5] Valyrakis M., A. Alexakis. 2016. Development of a “smart-pebble” for tracking sediment transport. International Conference on Fluvial Hydraulics River Flow 2016, St. Liouis, MO, 8p.</p><p>[6] Valyrakis, M., Farhadi, H. 2017. Investigating coarse sediment particles transport using PTV and “smart-pebbles” instrumented with inertial sensors, EGU General Assembly 2017, Vienna, Austria, 23-28 April 2017, id. 9980.</p>

Development, calibration and testing of a miniaturized instrumented particle for the study of entrainment of solids in turbulent flows

2020 ◽  
Author(s):  
Khaldoon AlObaidi ◽  
Manousos Valyrakis
Keyword(s):  
Inertial Sensor ◽  
Bedload Transport ◽  
Doppler Velocimetry ◽  
Mean Flow ◽  
Flume Experiments ◽  
Flow Measurements ◽  
Coarse Sediment ◽  
Wide Range ◽  
Sediment Particles ◽  
Sediment Entrainment

<p>Infrastructure damage due to riverbed and bank destabilisation or localised scour may result in considerable financial costs and even loss of life. As the risk to infrastructure keeps increasing due to climate change, the need to directly monitor it becomes crucial. Typically, hazards assessments for infrastructure near water are performed using relatively expensive and indirect methods that require field visits to remote and harsh environments to obtain mean flow measurements, using acoustic Doppler velocimetry [1], laser Doppler velocimetry [2] or water level stations along with discharge hydrographs [3]. In this work, a miniaturized instrumented particle that can provide a direct, non-intrusive and accessible method for the assessment of coarse sediment particles entrainment is developed, calibrated and tested. The particle has a diameter of only 3cm and is fitted with inertial microelectromechanical sensors (MEMS) that enable recording its three-dimensional displacement [4, 5]. The sensor is capable of recording acceleration, angular velocity and orientation at a rate of up to 1000Hz and has deployment time of at least one hour. The data can be transferred and downloaded to a PC or an SD card at a fast transfer rate and in easy format for further analysis. The calibration process of the sensor consisted of simple physical motions and the results of the calibration show that the uncertainties in the calibration experiments and in the accelerometer’s and gyroscope’s readings are deemed acceptable. The uncertainty quantification and noise estimation for the sensors, provide the input of the appropriate fusion filter that is applied to the raw data to achieve uncertainty reduction. The testing process consisted of moving the particle on a micro-bed topography and using a camera to record the distance it moved. The orientation of the instrumented particle during testing is determined by inertial sensor fusion of the raw readings of the 3 sensors. The results show that the instrumented particle’s motion could be detected accurately and therefore it could provide a method for direct assessment of the sediment entrainment due to hydrodynamic forces at low cost and in a non-intrusive and direct manner. The instrumented particle presented has a potential of use in a wide range of future applications around the fields of geosciences and environmental and infrastructures monitoring where sediment entrainment [5] and transport [6] is considered to be the governing process.</p><ol><li>Liu, D., Valyrakis, M., Williams, R. 2017. Flow Hydrodynamics across Open Channel Flows with Riparian Zones: Implications for Riverbank Stability.</li> <li>Diplas, P., Celik, A.O., Valyrakis, M., Dancey C.L. 2010. Some Thoughts on Measurements of Marginal Bedload Transport Rates Based on Experience from Laboratory Flume Experiments.</li> <li>Koursari, E., Wallace, S., Valyrakis, M., Michalis, P. 2019. Remote Monitoring of Infrastructure at Risk due to Hydrologic Hazards and Scour.</li> <li>Valyrakis, M. & Pavlovskis, E. 2014. "Smart pebble” design for environmental monitoring applications.</li> <li>Valyrakis M., A. Alexakis. 2016. Development of a “smart-pebble” for tracking sediment transport.</li> <li>Valyrakis, M., Farhadi, H. 2017. Investigating coarse sediment particles transport using PTV and “smart-pebbles” instrumented with inertial sensors.</li> </ol>

scholarly journals Variability of bedload transport rate during flood flows in the Zagożdżonka River

2010 ◽  
Vol 42 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Zbigniew Popek
Keyword(s):  
Laboratory Experiments ◽  
Bedload Transport ◽  
Transport Rate ◽  
Environmental Restoration ◽  
Bed Shear Stress ◽  
Measurement Results ◽  
Gauge Station ◽  
Flood Flows ◽  
Bedload Sediment ◽  
Flood Flow

Variability of bedload transport rate during flood flows in the Zagożdżonka River The paper presents the measurement results of bedload sediment transport during the flood flows observed in the Zagożdżonka River. The point for measuring the bedload transport, equipped with sediment catcher, devices for continuous measurements, and automated data recording, was localized above the Czarna gauge station in catchment studied by the Department of Hydraulic Engineering and Environmental Restoration, Warsaw University of Life Sciences - SGGW. The results of bedload transport measurements during one of the flood flow waves were compared to those calculated by using the Bagnold's formula. To determine the critical bed-shear stress, the Author's formula resulting from laboratory experiments, was used. Calculated variability of bedload transport rate during analyzed flood flow wave apparently differed from that directly measured. Nevertheless, mass of bedload achieved from calculations was lower by 6% than that from measurements, which can be considered as good result consistence.

Solids Distribution in Sediment-Laden Open-Channel Flow: Experiment and Prediction

2020 ◽  
Author(s):  
Václav Matoušek ◽  
Jan Krupička ◽  
Tomáš Picek ◽  
Štěpán Zrostlik
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Transport Model ◽  
Plane Surface ◽  
Open Channel Flow ◽  
Solid Particles ◽  
Experimental Results ◽  
Transport Layer ◽  
Experimental Investigations ◽  
Solids Concentration

Abstract Solid-liquid flow is studied in an open channel with a mobile bed at the condition of intense transport of solids. It is flow of high-concentrated mixture of coarse sediment and water over a plane surface of the bed eroded due to high bed shear. In the flow, solid particles are non-uniformly distributed across the flow depth. The flow develops a transport layer, adjacent to the the top of the bed, in which transported particles interact with each other. Results are presented of experimental investigations of the sediment-laden open-channel flow in a recirculating titling flume. The experiments included measurements (using ultrasonic techniques) of the distribution of solids velocity across the transport layer. The related distribution of solids concentration was deduced from the measured distribution of velocity and from other measured flow quantities. Since recently, a direct measurement of the solids distribution across the transport layer has been added to the experiments using a measuring technique svideo camera and a laser sheet. This work discusses results of combined measurements of the distributions of solids concentration and velocity in steady uniform turbulent flow for two lightweight solids fractions and various flow conditions (a broad range of the bed Shields parameter, discharge of solids, discharge of mixture, and the longitudinal slope of the bed). Furthermore, the camera-based measuring method and the deducing method for a determination of solids distribution are discussed and their results compared to show a good agreement in a majority of the test runs. The experimental results are compared with predictions of a recently developed bed-load transport model. Among other outputs, the model predicts the position of the top of the transport layer and the local velocity of sediment particles at this position. The presented model predictions agree well with experimental results based on the measured distibutions.

scholarly journals Validation of laser-penetration- and electrical-conductivity-based methods of concentration measurement in flow with intense transport of coarse sediment

2018 ◽  
Vol 180 ◽  
pp. 02048
Author(s):  
Jan Krupička ◽  
Václav Matoušek ◽  
Tomáš Picek ◽  
Štěpán Zrostlík
Keyword(s):  
Electrical Conductivity ◽  
High Speed ◽  
High Ratio ◽  
Depth Of Penetration ◽  
Local Flow ◽  
Coarse Sediment ◽  
Sediment Size ◽  
Laser Stripe ◽  
Methods Of Evaluation ◽  
Development And Validation

Lack of experimentally determined information on inner structure of flows carrying large amount of coarse sediment is an important limitation for development and validation of appropriate mathematical models. Measurement of local flow properties is particularly difficult in case of coarse sediment due to specific features associated with high ratio of the sediment size to the flow depth. This paper focusses on two methods of evaluation of vertical concentration profiles in the flow of a mixture of plastic grains and water in a laboratory flume. The first one was proposed by B. Spinewine et al. in 2011 and it is based on the relation between concentration of solids and the depth of penetration of a laser stripe to the flow, which is evaluated from a high speed camera record. The second method is based on well-known relation between the concentration and electrical conductivity of a mixture sensed by immersed probe. A sensitivity analysis of both the methods is performed to show the most crucial parameters affecting accuracy of the results. The methods are validated on data measured in fluidization cell with controlled particle concentration. Presented results on flow show limitations and potential of the methods for laboratory studies on liquid-granular flow.

Experimental study of sediment transport processes and size selectivity of eroded sediment on steep Pisha sandstone slopes

2020 ◽  
Author(s):  
Pan Zhang ◽  
Pingqing Xiao ◽  
Chunxia Yang
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Overland Flow ◽  
Yellow River ◽  
Transport Processes ◽  
The Yellow River ◽  
Size Selectivity ◽  
Coarse Sediment ◽  
Sediment Particles ◽  
Slope Flow

<p>The Pisha sandstone area on the Ordos Plateau of China is the primary source of coarse sediment of the Yellow River. Sediment size distribution and selectivity greatly affect sediment transport and deposition. Hence, sediment transport processes and size selectivity by overland flow on Pisha sandstone slopes were investigated in this study. Experiments were run with Pisha sandstone soil (bulk density of 1.35 g/cm<sup>3</sup>) under rainfall intensities of 87 and 133 mm/h with a 25° slope gradient, and the duration of simulated rainfall is 1 h. Sediment and runoff were sampled at 2-min intervals to examine the size distribution change of the eroded sediment. The particle composition, enrichment rate, fractal dimension, and time distribution characteristics of median grain size (d<sub>50</sub>) of eroded sediment were comprehensively analyzed. Statistical analyses showed that the erosion process of Pisha sandstone slope mainly transported coarse sediment. More than 40% of eroded sediment particles were coarse sediment, which will become the main sediment in the lower reaches of the Yellow River bed. The particle size of eroded sediment tended to gradually decrease with the continuous rainfall but remained larger than the background value of Pisha sandstone soil after refinement. The fractal dimension was positively correlated with the slope flow velocity, while the d<sub>50</sub> was negatively correlated with the slope flow velocity. Overall, these findings show a strong relationship between the sediment transport and flow velocity, which indicates that the selectivity and transportation of sediment particles on the Pisha sand slopes is mainly influenced by the hydrodynamic parameters of overland flow. This study provides a methodology and data references for studying the particle selectivity characteristics of eroded sediment and provides a scientific basis for revealing the mechanism of erosion and sediment yield in the Pisha sandstone area of China.</p>

Influence of Cylindrical Inclusion on the Elastic Field of Soft Material Loaded by Wedge Indenter

2014 ◽  
Vol 670-671 ◽  
pp. 664-667
Author(s):  
Xiao Hua Tan ◽  
Wei Qiu ◽  
Xia Xiao
Keyword(s):  
Rigid Inclusion ◽  
Elastic Field ◽  
Contact Stresses ◽  
Soft Material ◽  
Experimental Results ◽  
Cylindrical Inclusion ◽  
Experimental Procedure ◽  
Soft Matrix

In this work, the influence of a rigid cylindrical inclusion on the elastic field in a transparent soft material is studied by an embedded-grating technique. The same experimental procedure was implemented on two specimens, a homogeneous bulk soft material and the same material containing a rigid cylindrical inhomogeneity. Under the indentation of a rigid wedge, two kinds of deformation sectors underneath the contacting boundary are observed from experimental results. Furthermore, the shape of the deformation sectors is horizontally expanded due to the inclusion. A local fluctuation of contact stresses between the soft matrix and rigid inclusion are discussed.

scholarly journals Flow dynamics and bedload sediment transport around paired deflectors for fish habitat enhancement: a field study in the Nicolet River

2007 ◽  
Vol 34 (6) ◽  
pp. 761-769 ◽  
Author(s):  
David M Carré ◽  
Pascale M Biron ◽  
Susan J Gaskin
Keyword(s):  
Sediment Transport ◽  
Radio Frequency Identification ◽  
Fish Habitat ◽  
Sediment Traps ◽  
Bedload Transport ◽  
Flow Dynamics ◽  
Left Bank ◽  
Passive Integrated Transponder ◽  
Bedload Sediment ◽  
The Impact

Schemes to restore fish habitat in rivers often involve installing instream structures such as current deflectors to create and maintain riffle-pool sequences. However, there is a lack of field studies on the impact of these structures on flow dynamics and bed topography. The objective of this research is to characterize flow dynamics and sediment transport around paired deflectors used to enhance fish habitat in the Nicolet River, Quebec. Bed and bank topography surveys were taken with a total station, and velocity and bed shear stress estimates were obtained from an acoustic doppler velocimeter. Bedload sediment transport was assessed by two methods: tracer rocks (painted "particles" and passive integrated transponder tags) and sediment traps. Results show marked differences in bedload sediment transport patterns between the left bank and the right bank downstream of the deflectors. This is surprising considering that paired deflectors should produce a relatively symmetrical disruption to the flow field on each side. More high-flow dynamics data during overtopping conditions are required to understand the complex interactions between these instream structures and bedload transport. Key words: stream restoration, pool, bedload transport, radio frequency identification (RFID), passive integrated transponder (PIT) tags, fieldwork, deflectors, fish habitat.

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