Physics of Cohesive Sediment Flocculation and Transport PDF Download

Author: Bernhard Vowinckel
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0

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Book Description
Due to climate change, sea level rise and anthropogenic development, coastal communities have been facing increasing threats from flooding, land loss, and deterioration of water quality, to name just a few. Most of these pressing problems are directly or indirectly associated with the transport of cohesive fine-grained sediments that form porous aggregates of particles, called flocs. Through their complex structures, flocs are vehicles for the transport of organic carbon, nutrients, and contaminants. Most coastal/estuarine models neglect the flocculation process, which poses a considerable limitation of their predictive capability. We describe a set of experimental and numerical tools that represent the state-of-the-art and can, if combined properly, yield answers to many of the aforementioned issues. In particular, we cover floc measurement techniques and strategies for grain-resolving simulations that can be used as an accurate and efficient means to generate highly-resolved data under idealized conditions. These data feed into continuum models in terms of population balance equations to describe the temporal evolution of flocs. The combined approach allows for a comprehensive investigation across the scales of individual particles, turbulence and the bottom boundary layer to gain a better understanding of the fundamental dynamics of flocculation and their impact on fine-grained sediment transport.

Author: Minwoo Son
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Model results are compared with measured sediment concentration and velocity time series at the Ems/Dollard estuary. Numerical model predicts very small (or nearly zero) sediment concentration during slack tide when floc dynamics is neglected or incorporated incompletely. This feature is inconsistent with the observation. When considering variable fractal dimension and variable yield strength in the flocculation model, numerical model predicts much smaller floc settling velocity during slack tide and hence is able to predict measured concentration reasonably well. Model results further suggest that, when sediment concentration is greater than about 0.1 g/l, there exists a power law relationship between mass concentration and settling velocity except very near the bed where turbulent shear is strong. This observation is consistent with earlier laboratory and field experiment on floc settling velocity. It is concluded that a complete floc dynamics formulation is important to modeling cohesive sediment transport.

Author: Emmanuel Partheniades
Publisher: Butterworth-Heinemann
ISBN: 0080877974
Category : Science
Languages : en
Pages : 375

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Book Description
Control the impact of cohesive sediments on open channels by managing the effects of silt, clay and other sediments in harbors, estuaries and reservoirs. Cohesive Sediments in Open Channels provides you with a practical framework for understanding how cohesive sediments are transported, deposited and eroded. One of the first books to approach the subject from an engineering’s perspective, this book supplies insight into applying hydraulic design as well as understanding the behavior of cohesive sediments in a flow field. Properties and of the nature and the origin of the interparticle physicochemical forces The forces between clay particles and the process of flocculation Processes and dynamics of flocculation and the hydrodynamic behavior of cohesive sediments Transport processes of sediments by flowing water and related equations are first presented and explained Deposition and resuspension of beds deposited from suspension from flowing waters Engineering applications of the hydraulics of cohesive sediments

Author: Silvia Susana Ginsberg
Publisher: IntechOpen
ISBN: 9789533071893
Category : Science
Languages : en
Pages : 348

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Book Description
Sediment transport is a book that covers a wide variety of subject matters. It combines the personal and professional experience of the authors on solid particles transport and related problems, whose expertise is focused in aqueous systems and in laboratory flumes. This includes a series of chapters on hydrodynamics and their relationship with sediment transport and morphological development. The different contributions deal with issues such as the sediment transport modeling; sediment dynamics in stream confluence or river diversion, in meandering channels, at interconnected tidal channels system; changes in sediment transport under fine materials, cohesive materials and ice cover; environmental remediation of contaminated fine sediments. This is an invaluable interdisciplinary textbook and an important contribution to the sediment transport field. I strongly recommend this textbook to those in charge of conducting research on engineering issues or wishing to deal with equally important scientific problems.

Author: Ashish J Mehta
Publisher: World Scientific Publishing Company
ISBN: 9814449504
Category : Technology & Engineering
Languages : en
Pages : 1060

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Book Description
This book presents observations on the phenomena of fine sediment transport and their explanations under process-related divisions such as flocculation, erosion, and deposition.The text is a compilation of the author's lecture notes from nearly four decades of teaching and guiding graduate students in civil and coastal engineering. Illustrations of fine sediment transport processes and their complexities given in the book are taken from field and laboratory-based observations by the author and his students, as well as numerous investigators.The wide-ranging composition of particles (of inorganic and organic matter), their universal presence and their complex interactions with hydraulic forces make this branch of science a difficult one to deal with in a single treatise. It is therefore essential to study fine sediment transport as an independent subject rather than cover it in no more than a single chapter as many texts on coarse sediment transport have done.Even though the entire coverage is “introductory”, the twelve chapters collectively include more material than what can be reasonably dealt with in a one semester, three-credit course.The book includes an extensive description of the components of fine-grained — especially cohesive — sediment transport. It covers the development of the subject in scientific and engineering applications mainly from the 1950s to its present state. Solved examples and chapter-end exercises are also included.This text is aimed at senior civil engineering undergraduates and graduate students who, in the normal course of their study, seldom come across the subject of fine sediment transport in their curricula. Interested students should have a basic understanding of the mechanics of fluid flow and open channel hydraulics.

Author: Andrew Manning
Publisher: BoD – Books on Demand
ISBN: 953511039X
Category : Science
Languages : en
Pages : 392

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Book Description
Sediment Transport Processes and their Modelling Applications is a book which covers a wide range of topics. The effective management of many aquatic environments, requires a detailed understanding of sediment dynamics. This has both environmental and economic implications, especially where there is any anthropogenic involvement. Numerical models are often the tool used for predicting the transport and fate of sediment movement in these situations, as they can estimate the various spatial and temporal fluxes. However, the physical sedimentary processes can vary quite considerably depending upon whether the local sediments are fully cohesive, non-cohesive, or a mixture of both types. For this reason for more than half a century, scientists, engineers, hydrologists and mathematicians have all been continuing to conduct research into the many aspects which influence sediment transport. These issues range from processes such as scour, erosion and deposition, to how sediment process observations can be applied in sediment transport modelling frameworks. This book reports the findings from recent research in applied sediment transport which has been conducted in a wide range of aquatic environments. The research was carried out by researchers who specialise in the transport of sediments and related issues.

Author: Neville Burt
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 490

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Book Description
There is an alarming tendency today to assume that something calculated by a computer must be correct, yet the phrase 'garbage in, garbage out' (gigo) is possibly nowhere more (generally) appropriate than in computer modelling of cohesive sediment behaviour. The behaviour of 'mud' is highly complex and one only needs to look at a sample under a microscope to see why - the variety of particle shapes, not to mention the presence of living organisms, make it a substance with properties virtually unique to its situation which even change with time. For many years most researchers tended to avoid it, preferring to study sand and gravel, but a dedicated few tackled it and found a forum for discussing their work in the first Cohesive Sediments Workshop in Florida in 1980. The workshop met about every three years resulting in publication of some of the most definitive papers on the subject. By 1994 it was time to recognise the extensive research being carried on in Europe by holding the workshop in that region. Intercoh '94 (the 4th Nearshore and Estuarine Cohesive Sediment Transport Conference) drew together about 100 of the world's leading researchers in the field. The resulting papers, presented in this volume, truly represent the definitive state of the art on the measurement and modelling of mud properties today.

Author: Ashish J. Mehta
Publisher: American Geophysical Union
ISBN:
Category : Science
Languages : en
Pages : 600

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Book Description
This book discusses cohesive sediments. It is based on presentations at the Nearshore and Estuarine Cohesive Sediment Transport Workshop held in 1991.

Author: Johan C. Winterwerp
Publisher: Elsevier
ISBN: 0080531660
Category : Science
Languages : en
Pages : 731

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Book Description
Cohesive sediment, or mud, is encountered in most water bodies throughout the world. Often mud is a valuable resource, synonymous with fertile land, enriching the natural environment and used as an important building material. Yet mud also hinders navigation and consequently, dredging operations have been carried out since ancient times to safeguard navigation. Unfortunately, many mud deposits are now contaminated, endangering the eco-system and increasing the costs of dredging operations. The transport and fate of mud in the environment are still poorly understood and the need for basic research remains. This text contains the proceedings of the INTERCOH-2000 conference on progress in cohesive sediment research. It was the sixth in a series of conferences initially started by Professor Ashish Mehta in 1984 as a "Workshop on Cohesive Sediment Dynamics with Special Reference to the Processes in Estuaries". During these conferences the character of the first workshop has always been maintained, that is, small scale and dedicated to the physical and engineering aspects of cohesive sediments, without parallel sessions, but with ample time for discussions during and after the presentations, and followed by a book of proceedings containing thoroughly reviewed papers. INTERCOH-2000 was integrated with the final workshop of the COSINUS project. This project was carried out as a part of the European MAST-3 programme, and almost all European cohesive sediment workers were involved. INTERCOH-2000 focused on the behaviour and modelling of concentrated benthic suspensions, i.e. high-concentrated near-bed suspensions of cohesive sediment. Special attention was paid to: sediment - turbulence interaction; flocculation and settling velocity; high-concentrated mud suspensions; processes in the bed - consolidation; processes on the bed - erosion; field observations on mud dynamics; instrumentation; and numerical modelling.

Author: I. G. Droppo
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
"In the history of sediment transport research within hydrological sciences, there perhaps been no greater paradigm shift than that which has been provided by the identification of flocculation as a dominant mechanism operating within, and mediating, cohesive suspended sediment transport. Flocculation (the process of aggregating smaller particles together to form larger particles) significantly modifies the hydrodynamic properties of the sediment by altering their effective size, shape, density, porosity and composition. Such changes have a dramatic impact on the downward flux of sediments and as such influence the transportation and fate of suspended sediments"--Abstract.