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>

Assessing thresholds for fluvial entrainment with instrumented particles

2021 ◽  
Author(s):  
Khaldoon AlObaidi ◽  
Manousos Valyrakis
Keyword(s):  
Sediment Transport ◽  
Turbulent Flows ◽  
River Flow ◽  
Low Cost ◽  
Experimental Studies ◽  
Energy Criterion ◽  
Field Studies ◽  
Incipient Motion ◽  
Sediment Particles ◽  
Sediment Entrainment

<p>Sediment transport is considered to be the governing process in many applications around the fields of geosciences and engineering as well as infrastructure and environment monitoring. Of a special interest to which scientists and engineers have dedicated a lot of time and experimental studies in the last century is the conditions for initiation of sediment entrainment, or incipient motion. In the literature, there are different criteria for determining the conditions that can result in initiation of sediment entrainment. Among these criteria, the impulse (or energy) criterion [1-2] captures the actual physics of sediment entrainment since it accounts for both the magnitude and the duration of the turbulent flow events that can result in initiation of a particle’s motion. The experimental and field studies of incipient motion use relatively expensive tools, like Particle image velocimetry (PIV) or Acoustic Doppler velocimetry (ADV), with indirect methods to determine flow parameters that could be related to predicting sediment entrainment. However, technological developments in recent decades has made it possible to assess sediment entrainment directly. Recently, a number of research studies [3-4] have suggested linking micro-electromechanical system (MEMS) recordings that consist of accelerometers, gyroscopes and magnetometer as well as an internal digital motion processor that are interconnected forming inertial measurement units (IMUs) to the probability of entrainment of individual particles. The particles have been presented provide a direct, non-intrusive, low-cost and accessible method for assessing the probability of entrainment of individual sediment particles rather than inferred using near bed flow diagnostics. In this work, an instrumented particle of 3cm in diameter [5] is used to investigate experimentally the conditions that can result in initiation of sediment entrainment for a range of flowrates that represent the near threshold conditions. The data is used to derive metrics like frequency of entrainment that could be linked to the probability of entrainment of individual sediment particles which could be used as an indicator of the risk of riverbed destabilization based on well-established theories in hydraulic engineering. Additionally, the novelty of this work is explicitly linking the probability of entrainment to the flow hydrodynamics. In addition to that, a stochastic analysis is performed to identify the relevance of certain flow structures (sweeps) to the incipient entrainment of the instrumented particle.</p><p>[1] Valyrakis M., Diplas P., Dancey C.L., Greer K., Celik A.O. (2010). Role of Instantaneous Force Magnitude and Duration on Particle Entrainment. JGR, 115, 1-18.</p><p>[2] Valyrakis M., Diplas P., Dancey C.L. (2013). Entrainment of Coarse Particles in Turbulent Flows: An Energy Approach. JGR- Earth Surf., 118, 42-53.</p><p>[3] Valyrakis, M., Alexakis, A. (2016). Development of a “smart-pebble” for tracking sediment transport. River Flow 2016, MO, USA.</p><p>[4] Al-Obaidi, K., Xu, Y., Valyrakis, M. (2020). The Design and Calibration of Instrumented Particles for Assessing Water Infrastructure Hazards. JSAN, 9, 3, 36.</p><p>[5] Al-Obaidi, K., Valyrakis, M. (2020). A sensory instrumented particle for environmental monitoring applications: development and calibration. IEEE sensors journal (accepted).</p>

Bridge pier scour hazards assessment using smart-spheres

2020 ◽  
Author(s):  
Alex Corrigan ◽  
Hassan Elmubarak ◽  
Yi Xu ◽  
Panagiotis Michalis ◽  
Manousos Valyrakis
Keyword(s):  
Sediment Transport ◽  
Turbulent Flows ◽  
River Flow ◽  
Fuzzy Inference ◽  
Weather Conditions ◽  
Bridge Pier ◽  
Bridge Scour ◽  
Pier Scour ◽  
International Conference ◽  
Bridge Pier Scour

<p>Under climate change, shifting  weather conditions, (both in terms of increasing frequency and intensifying magnitude) result in increasing occurrence of catastrophic failures of the constantly exposed and ageing infrastructure, across the world. Energetic flow events, advected past hydraulic infrastructure (such as bridge piers and abutments), may lead to scour [1, 2, 3], which is the primary cause of bridge collapses, resulting in high socio-economical costs, including loss of life.</p><p>This research aims to demonstrate the use of a novel monitoring device for the assessment of scour initiated by turbulent flows. This is pursued via the use of a miniaturized instrumented particle, namely “smart-sphere”, to record directly the frequency of entrainment from its downstream placement a model bridge pier at the Water Engineering lab of the University of Glasgow [4, 5, 6]. The change in entrainment frequencies is used as a metric to assess the increasing risk to scour, with increasing flow conditions, recorded acoustic Doppler velocimetry (ADV). The utility of the method as well as the potential use of the acquired data for prediction of bridge pier scour is presented and the tool as well is discussed with the potential for use to an appropriate field site [7, 8, 9].</p><p> </p><p>Acknowledgments</p><p>This research project has been supported by Transport Scotland, under the 2019/20 Innovation Fund and the Student research award.</p><p> </p><p>References</p><p>[1] 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>[2] Yagci, O., Celik, F., Kitsikoudis, V., Kirca, O., Hodoglu, C., Valyrakis, M., Duran, Z., Kaya S. 2016. Scour patterns around individual vegetation elements, Advances in Water Resources, 97, pp 251-265, doi: 10.1016/j.advwatres.2016.10.002.</p><p>[3] Michalis, P., Saafi, M. and M.D. Judd. (2012) Integrated Wireless Sensing Technology for Surveillance and Monitoring of Bridge Scour. Proceedings of the 6th International Conference on Scour and Erosion, France, Paris, pp. 395-402.</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><p>[7] Valyrakis, M., Diplas, P., Dancey, C.L. 2011. Prediction of coarse particle movement with adaptive neuro-fuzzy inference systems, Hydrological Processes, 25 (22). pp. 3513-3524. ISSN 0885-6087, doi:10.1002/hyp.8228.</p><p>[8] Valyrakis, M., Michalis, P., Zhang, H. 2015a. A new system for bridge scour monitoring and prediction. Proceedings of the 36th IAHR World Congress, The Hague, the Netherlands, pp. 1-4.</p>

scholarly journals Analisa Angkutan Sedimen Pada Hulu Bendung Aepodu Kabupaten Konawe Selatan

2021 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Ramadhan Hidayat Putra ◽  
Amad Syarif Syukri ◽  
Catrin Sudarjat ◽  
Vickky Anggara Ilham
Keyword(s):  
Sediment Transport ◽  
River Flow ◽  
Suspended Load ◽  
Bedload Transport ◽  
Bed Load ◽  
Average Flow ◽  
Load Transport ◽  
Bed Load Transport ◽  
Transport Analysis

Research on Aepodu Weir Sediment Transport Analysis in South Konawe District, based on observations in the field, Aepodu Weir hasa sediment buildup that has now exceeded the height of the weirlight house. The purpose of the study was to analyze the magnitudeof Aepodu river flow and to analyze the amount of sedimenttransport that occurred in the Aepodu dam. The method used todetermine the amount of bed load transport uses stchoklitscht, whilefor transporting suspended load using forcheimer.The results of the analysis of the average flow of the Aepodu riverwere 3,604 m3/ second. Sediment transport that occurs in Aepoduweir is Bedload transport (Qb) of 291625.771 tons / year, andsuspended load transport (Qs) of 16972,423 tons / year, so that thetotal sediment transport (QT) is 308598,194 tons / year.

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>

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%.

scholarly journals Macro-Turbulent Flow and Its Impacts on Sediment Transport Potential of a Subarctic River during Ice-Covered and Open-Channel Conditions

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1874
Author(s):  
Eliisa Lotsari ◽  
Michael Dietze ◽  
Maria Kämäri ◽  
Petteri Alho ◽  
Elina Kasvi
Keyword(s):  
Sediment Transport ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Velocity Fluctuation ◽  
Open Channel ◽  
Flow Characteristics ◽  
Bedload Transport ◽  
Low Flow ◽  
Critical Threshold ◽  
Flow Conditions

Macro-turbulent flows (i.e., coherent flow structures reaching through the whole water column), have not been studied widely in northern seasonally frozen rivers during both open-channel and ice-covered flow conditions. Thus, we aim: (1) to detect and compare the macro-turbulent flow, both at open-channel and ice-covered flow conditions; (2) to explore spatial variation of macro-turbulent flow characteristics within a meander bend; and (3) to detect the effects of near-bed layer velocity fluctuation on bedload transport during differing overall flow conditions. The analyses are based on 5–10 min-long acoustic Doppler current profiler (ADCP) measurements from a subarctic river. The ice-covered low flow, and open-channel higher and lower flow conditions were measured over the period of 2016 to 2020. This study found that macro-turbulent flow existed at all measurement locations under both open-channel and ice-covered flow conditions. Macro-turbulent flow was most consistent and obvious in the streamwise velocity component, and in particular at the inlet and outlet of the investigated meander bend. During all seasons, the near-bed velocities consistently exceeded the sufficient amount for sediment transport. At inlet and outlet areas, the greatest near-bed velocity fluctuation across the critical threshold for sediment transport coincided with the measurement times having frequent macro-turbulent flow.

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>

Research on the Pollution Diffusion Regularity near Sewage Outlet Areas in Yuncheng Reach of the Fen River

2011 ◽  
Vol 383-390 ◽  
pp. 2430-2436
Author(s):  
Jian Hua Hou ◽  
Min Quan Feng ◽  
Xiao Peng Xing ◽  
Zhen Hua Hou
Keyword(s):  
Water Quality ◽  
Flow Field ◽  
Water Depth ◽  
Concentration Gradient ◽  
River Flow ◽  
Measured Data ◽  
Quality Model

The purpose of this paper is to find the pollution diffusion regularity near sewage outlet area of Yuncheng reach of the Fen River. A 2-D water hydrodynamic and quality model was used to simulate flow field, the water quality and contamination dispersion. The parameters of the model were calibrated with measured data of the water depth, flow and water quality in Yuncheng reach of the Fen River. According to the simulated result, the total area of pollution belt with 19 sewage outlets is 8.89km2 in normal year. And 3.89% of the reach has a worse water quality than V class in standard. The percentage of V and Ⅳ Class of water is 69.17% and 26.94%.In dry year, the total area of pollution belt with 19 sewage outlets is 8.89km2.The percentage of inferior V, V and Ⅳ Class of water is 27.80%, 69.46% and 2.74%. It was shown by the simulated results that the concentration gradient decreases with increasing distance to the outlets and the dilution and dispersion of pollutants was enhanced by a greater river flow.

scholarly journals A reduced-complexity model for river delta formation – Part 1: Modeling deltas with channel dynamics

2015 ◽  
Vol 3 (1) ◽  
pp. 67-86 ◽  
Author(s):  
M. Liang ◽  
V. R. Voller ◽  
C. Paola
Keyword(s):  
Sediment Transport ◽  
Flow Field ◽  
Water Surface ◽  
Surface Profile ◽  
River Delta ◽  
Suspended Sediment Transport ◽  
Channel Dynamics ◽  
Wide Range ◽  
Delta Formation ◽  
Reduced Complexity

Abstract. In this work we develop a reduced-complexity model (RCM) for river delta formation (referred to as DeltaRCM in the following). It is a rule-based cellular morphodynamic model, in contrast to reductionist models based on detailed computational fluid dynamics. The basic framework of this model (DeltaRCM) consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include a depth-averaged flow field, water surface elevation and bed topography that evolve in time. Results show that DeltaRCM is able (1) to resolve a wide range of channel dynamics – including elongation, bifurcation, avulsion and migration – and (2) to produce a variety of deltas such as alluvial fan deltas and deltas with multiple orders of bifurcations. We also demonstrate a simple stratigraphy recording component which tracks the distribution of coarse and fine materials and the age of the deposits. Essential processes that must be included in reduced-complexity delta models include a depth-averaged flow field that guides sediment transport a nontrivial water surface profile that accounts for backwater effects at least in the main channels, both bedload and suspended sediment transport, and topographic steering of sediment transport.

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