scholarly journals An overview of underwater sound generated by inter-particle collisions and its application to the measurements of coarse sediment bedload transport

2014 ◽  
Vol 2 (2) ◽  
pp. 605-633 ◽  
Author(s):  
P. D. Thorne
Keyword(s):  
Bedload Transport ◽  
Transport Processes ◽  
High Temporal Resolution ◽  
Underwater Sound ◽  
Particle Collisions ◽  
Acoustic Data ◽  
Mobile Bed ◽  
Bedload Sediment ◽  
Bed Material ◽  
Interparticle Collisions

Abstract. Over the past two to three decades the concept of using sound generated by the interparticle collisions of mobile bed material, has been investigated to assess if underwater sound can be utilised as a proxy for the estimation of bedload transport. In principle the acoustic approach is deemed to have the potential to provide non-instrusive, continuous, high temporal resolution measurements of bedload transport. It has been considered that the intensity of the sound radiated should be related to the ammount of mobile material and the frequency spectrum to the size of the material. To be able to fully realise this use of acoustics requires an understanding of the parameters which control the generation of sound as particles impact. In the present work the aim is to provide marine scientists developing acoustics to measure bedload transport with a description of how sound is generated when particles undergo collision underwater. To investigate the properties of the sound generated, examples are provided under different conditions of impact. It is considered that an understanding of the origins of the sound generation, will provide a basis for the interpretation of acoustic data collected in the marine environment, for the study of bedload sediment transport processes.

scholarly journals An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport

2014 ◽  
Vol 2 (2) ◽  
pp. 531-543 ◽  
Author(s):  
P. D. Thorne
Keyword(s):  
Bedload Transport ◽  
Transport Processes ◽  
High Temporal Resolution ◽  
Underwater Sound ◽  
Acoustic Data ◽  
The Past ◽  
Mobile Bed ◽  
Bedload Sediment ◽  
Bed Material ◽  
Interparticle Collisions

Abstract. Over the past 2 to 3 decades the concept of using sound generated by the interparticle collisions of mobile bed material has been investigated to assess if underwater sound can be utilised as a proxy for the estimation of bedload transport. In principle the acoustic approach is deemed to have the potential to provide non-intrusive, continuous, high-temporal-resolution measurements of bedload transport. It has been considered that the intensity of the sound radiated should be related to the amount of mobile material and the frequency spectrum to the size of the material. To be able to fully realise this use of acoustics requires an understanding of the parameters which control the generation of sound as particles impact. In the present work the aim is to provide scientists developing acoustics to measure bedload transport with a description of how sound is generated when particles undergo collision underwater. To investigate the properties of the sound generated, examples are provided under different conditions of impact. It is considered that providing an overview of the origins of the sound generation will provide a basis for the interpretation of acoustic data, collected in the marine environment for the study of bedload sediment transport processes.

Bed configuration and microscale processes in alluvial channels

1993 ◽  
Vol 17 (2) ◽  
pp. 123-136 ◽  
Author(s):  
André Robert
Keyword(s):  
Probabilistic Approach ◽  
Field Measurements ◽  
Bedload Transport ◽  
Transport Processes ◽  
Coarse Grained ◽  
Small Scale ◽  
Alluvial Channels ◽  
Gravel Beds ◽  
Sand And Gravel ◽  
Bed Material

Numerous recent studies on fluvial processes, both in Canada and internationally, have focused on small-scale phenomena. Investigations on the characterization of surface roughness in coarse-grained channels and its links with flow resistance and sediment transport processes have been a dominant field of research. Closely related is a second major area of investigation on turbulent flow structures in boundary layers over both sand and gravel beds and their relations with the transport of bed material. Phenomena potentially related to 'bursting' have been shown to control bedload transport processes and the concentration of sediment in suspension. Detailed investigations have also been conducted on the links between flow turbulence, bed material movement, and bed morphology at channel junctions. Finally, selective entrainment and transport of individual coarse particles have been studied from field measurements and laboratory experi ments. Emphasis has been put on bed microtopography, surface structure and texture, and on a probabilistic approach to bedload transport.

Bedforms, bed material, and bedload transport in a salt-wedge estuary: Fraser River, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1440-1452 ◽  
Author(s):  
R. A. Kostaschuk ◽  
M. A. Church ◽  
J. L. Luternauer
Keyword(s):  
British Columbia ◽  
River Discharge ◽  
Bedload Transport ◽  
Fraser River ◽  
Seasonal Fluctuations ◽  
Salt Wedge ◽  
Migration Rates ◽  
Material Load ◽  
Bed Material

The lower main channel of the Fraser River, British Columbia, is a sand-bed, salt-wedge estuary in which variations in velocity, discharge, and bedform characteristics are contolled by river discharge and the tides. Bed-material composition remains consistent over the discharge season and in the long term. Changes in bedform height and length follow but lag behind seasonal fluctuations in river discharge. Migration rates of bedforms respond more directly to river discharge and tidal fall than do height and length. Bedform characteristics were utilized to estimate bedload transport in the estuary, and a strong, direct, but very sensitive relationship was found between bed load and river discharge. Annual bedload transport in the estuary is estimated to be of the order of 0.35 Mt in 1986. Bedload transport in the estuary appears to be higher than in reaches upstream, possibly because of an increase in sediment movement along the bed to compensate for a reduction in suspended bed-material load produced by tidal slack water and the salt wedge.

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.

scholarly journals Passive acoustic measurement of bedload grain size distribution using self-generated noise

2018 ◽  
Vol 22 (1) ◽  
pp. 767-787 ◽  
Author(s):  
Teodor Petrut ◽  
Thomas Geay ◽  
Cédric Gervaise ◽  
Philippe Belleudy ◽  
Sebastien Zanker
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Measurement Techniques ◽  
Bedload Transport ◽  
Transport Processes ◽  
Signal Spectrum ◽  
Inversion Method ◽  
Passive Acoustic

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

Modeling the Motion of Slurry Nanoparticles During Chemical Mechanical Polishing

Tribology ◽  
2005 ◽  
Author(s):  
Elon J. Terrell ◽  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Mathematical Model ◽  
Particle Motion ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Surface Wear ◽  
Particle Collisions ◽  
Nanoscale Particles ◽  
Interparticle Collisions ◽  
Global Surface

Chemical mechanical polishing (CMP) has emerged as a commonly used method for achieving global surface planarization of micro-/nano-scale systems during fabrication. During CMP, the wafer to be polished is pressed against a rotating polymeric pad that is flooded with slurry. The motion of the wafer surface against the asperities of the pad and the abrasive nanoscale particles in the slurry causes the surface of the wafer to be polished to an atomically smooth level. Past studies have shown that the wear distribution is a function of the distribution of slurry particles in the wafer/pad interface, and thus it is desirable to model the migration of particles in order to predict the wear of the wafer surface. The current study involves the creation and simulation of a mathematical model which predicts the paths of slurry particles in a Lagrangian reference frame. The model predicts the effects of the various forces on each particle to determine its motion. The model also accounts for interparticle collisions and wafer/particle and pad/particle collisions. It is expected that the particle motion that is predicted from this model will allow for a more accurate correlation of the wafer surface wear distribution.

scholarly journals Numerical simulation of bedload tracer transport associated with sand bar formation, bank erosion, and channel migration

2018 ◽  
Vol 40 ◽  
pp. 02013
Author(s):  
Toshiki Iwasaki ◽  
Satomi Yamaguchi ◽  
Hiroki Yabe
Keyword(s):  
Numerical Model ◽  
Bank Erosion ◽  
Bedload Transport ◽  
Transport Processes ◽  
Tracer Transport ◽  
Channel Migration ◽  
River Systems ◽  
Sand Bars ◽  
Tracer Particles ◽  
Bar Formation

An understanding of bedload transport processes is an essential research goal for better prediction of river morphology and morphodynamics as well as the transport and fate of sediment-bound materials in river systems. Passive tracer particles have been used widely to monitor bedload transport processes in rivers by measuring the spatiotemporal distribution of the bedload tracers. Here, we propose a numerical model for reproducing the transport of bedload tracers in river systems, more specifically, the behaviours of bedload tracers under the influence of complex river morphodynamics. A two-dimensional morphodynamic model is combined with a flux-based bedload tracer model with use of the active layer approach. The model is applied to a laboratory experiment that demonstrates the transport processes within the channel of bedload tracers supplied from the floodplain. The numerical model effectively reproduces the main features of the experiment, namely, the bedload tracers supplied from the floodplain due to bank erosion deposit onto sand bars developed within the channel. Because the sand bars cause a very long residence time of the bedload tracers within the bed, the transport speed of the tracers is slowed significantly under the influence of bar formation and channel migration.

scholarly journals Sediment Transport Processes during Barrier Island Inundation under Variations in Cross-Shore Geometry and Hydrodynamic Forcing

2019 ◽  
Vol 7 (7) ◽  
pp. 210
Author(s):  
Anita Engelstad ◽  
Gerben Ruessink ◽  
Piet Hoekstra ◽  
Maarten van der Vegt
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Barrier Island ◽  
Wave Model ◽  
Short Wave ◽  
Bedload Transport ◽  
Transport Processes ◽  
Mean Flow ◽  
Flow Transport ◽  
The Mean

Inundation of barrier islands can cause severe morphological changes, from the break-up of islands to sediment accretion. The response will depend on island geometry and hydrodynamic forcing. To explore this dependence, the non-hydrostatic wave model SWASH was used to investigate the relative importance of bedload transport processes, such as transport by mean flow, short- (0.05–1 Hz) and infragravity (0.005–0.05 Hz) waves during barrier island inundation for different island configurations and hydrodynamic conditions. The boundary conditions for the model are based on field observations on a Dutch barrier island. Model results indicate that waves dominate the sediment transport processes from outer surfzone until landwards of the island crest, either by transporting sediment directly or by providing sediment stirring for the mean flow transport. Transport by short waves was continuously landwards directed, while infragravity wave and mean flow transport was seaward or landward directed. Landward of the crest, sediment transport was mostly dominated by the mean flow. It was forced by the water level gradient, which determined the mean flow transport direction and magnitude in the inner surfzone and on the island top. Simulations suggest that short wave and mean flow transport are generally larger on steeper slopes, since wave energy dissipation is less and mean flow velocities are higher. The slope of the island top and the width of the island foremost affect the mean flow transport, while variations in inundation depth will additionally affect transport by short-wave acceleration skewness.

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