Download or read book Coastal Bottom Boundary Layers and Sediment Transport written by Peter Nielsen and published by World Scientific. This book was released on 1992 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is intended as a useful handbook for professionals and researchers in the areas of Physical Oceanography, Marine Geology, Coastal Geomorphology and Coastal Engineering and as a text for graduate students in these fields. With its emphasis on boundary layer flow and basic sediment transport modelling, it is meant to help fill the gap between general hydrodynamic texts and descriptive texts on marine and coastal sedimentary processes. The book commences with a review of coastal bottom boundary layer flows including the boundary layer interaction between waves and steady currents. The concept of eddy viscosity for these flows is discussed in depth because of its relation to sediment diffusivity. The quasi-steady processes of sediment transport over flat beds are discussed. Small scale coastal bedforms and the corresponding hydraulic roughness are described. The motion of suspended sand particles is studied in detail with emphasis on the possible suspension maintaining mechanisms in coastal flows. Sediment pickup functions are provided for unsteady flows. A new combined convection-diffusion model is provided for suspended sediment distributions. Different methods of sediment transport model building are presented together with some classical models.

Download or read book A Short Manual of Coastal Bottom Boundary Layers and Sediment Transport written by P. Nielsen and published by . This book was released on 1985 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Series on Ocean Engineering Volume 4 Coastal Bottom Boundary Layers and Sediment Transport written by Peter Nielsen and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanics of Coastal Sediment Transport written by J?rgen Freds?e and published by World Scientific. This book was released on 1992 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book treats the subject of sediment transport in the marine environment, covering transport of non-cohesive sediment by waves and current in- and outside the surf zone. It can be read independently, but a background in hydraulics and basic wave mechanics is required. It is intended for M.Sc. and Ph.D. students. The primary aim of the book is to describe the physical processes of sediment transport and how to represent them in mathematical models. It does not present a large number of different formulae for the sediment transport rates under various conditions. The book can be divided in two main parts; in the first, the relevant hydrodynamic theory is described; in the second, sediment transport and morphological development are treated. The hydrodynamic part contains a review of elementary theory for water waves, chapters on the turbulent wave boundary layer and the turbulent interaction between waves and currents, and finally, surf zone hydrodynamics and wave driven currents. The part on sediment transport introduces the basic concepts (critical bed shear stress, bed load, suspended load and sheet layer, near-bed concentration, effect of sloping bed); it treats suspended sediment in waves and current and in the surf zone, and current and wave-generated bed forms. Finally, the modelling of cross-shore and long-shore sediment transport is described together with the development, of coastal profiles and coastlines.

Download or read book Modelling Sheet Flow Sediment Transport in Wave Bottom Boundary Layers Using Discrete Element Modelling written by and published by . This book was released on 2004 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediment transport in oscillatory boundary layers is a driving mechanism of coastal geomorphologic change. Most formulae for bed-load transport in near-shore regions subsume the smallest-scale physics of the phenomena by parameterizing interactions between particles. In contrast, the authors directly simulate granular physics in the wave-bottom boundary layer using a discrete-element model consisting of a three-dimensional particle phase coupled to a one-dimensional fluid phase via Newton's Third Law through forces of buoyancy, drag, and added mass. The particulate sediment phase is modeled using discrete, non-spherical particles formed to approximate natural grains by overlapping two spheres. Both the size of each sphere and the degree of overlap can be varied for these composite particles to generate a range of non-spherical grains. Simulations of particles having a range of shapes showed that the critical angle - the angle at which a grain pile will fail when tilted slowly from rest - increases from approximately 26 degrees for spherical particles to nearly 39 degrees for highly non-spherical composite particles having a dumbbell shape. Simulations of oscillatory sheet flow were conducted using composite particles with an angle of repose of approximately 33 degrees and a Corey shape factor greater than about 0.8, similar to the properties of beach sand. The results from the sheet-flow simulations with composite particles agreed more closely with laboratory measurements than similar simulations conducted using spherical particles. The findings suggest that particle shape may be an important factor for determining bed-load flux, particularly for larger bed slopes. (5 figures, 18 refs.).

Download or read book Modelling and Analysis of Fine Sediment Transport in Wave Current Bottom Boundary Layer written by Liqin Zuo and published by CRC Press. This book was released on 2018-06-19 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. This thesis aims to better understand fine sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL). Field observations, experimental data analysis, theoretical analysis and numerical models are employed. Silt-dominated sediments are sensitive to flow dynamics and the suspended sediment concentration (SSC) increase rapidly under strong flow dynamics. This research unveils several fundamental aspects of silty sediment, i.e., the criterion of the incipient motion, the SSC profiles and their phase-averaged parameterization in wave-dominated conditions. An expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. A process based intra-wave 1DV model for flow-sediment dynamics near the bed is developed in combined wave-current conditions. The high concentration layer (HCL) was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the SSC in the HCL. Finally, based on the 1DV model, the formulations of the mean SSC profile of silt-sand sediments in wave conditions were proposed. The developed approaches are expected to be applied in engineering practice and further simulation.

Download or read book Turbulence resolving Numerical Investigations of Coastal Bottom Boundary Layer and Fine Sediment Transport written by Liangyi Yue and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bottom boundary layer in coastal ocean is of intrinsic scientific importance in many disciplines, serving as the near-bed passage where many benthic transport processes occur and it is a vital bridge connecting the wave propagation, currents and upper ocean processes with the seafloor. The present work focuses on the fluid dynamics in coastal bottom boundary layer (CBBL) and the associated sediment transport process using the technique of turbulence-resolving numerical simulation (TRNS). Particularly, we are interested in the entrainment, suspension and transport of fine sediment in the wave bottom boundary layer (WBBL) driven by surface gravity waves.

Download or read book Wave Boundary Layers and Their Relation to Sediment Transport written by Paul G. Teleki and published by . This book was released on 1972 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Benthic Boundary Layer written by Bernard P. Boudreau and published by Oxford University Press. This book was released on 2001-03-22 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The benthic boundary layer is the zone of water and sediment immediately adjacent to the bottom of a sea, lake, or river. This zone is of considerable interest to biologists, geochemists, sedimentologists, and engineers because of very strong gradients of energy, dissolved and solid chemical components, suspended matter, and the number of organisms that live there. It is, for example, the sink for anthropogenic substances and the home of microscopic plant life that provides the nutrients that determine fish populations--and ultimately the size of the fisheries. This book of original chapters edited by Professors Boudreau and Jorgensen, both leading researchers in the field, will meet the need for an up-to-date, definitive text/reference on measurements, techniques, and models for transport and biochemical processes in the benthic boundary layer. Each chapter provides a comprehensive review of a selected field, with illustrated examples from the authors' own work. The book will appeal to professionals and researchers in marine biology, marine chemistry, marine engineering, and sedimentology.

Download or read book Experimental and Theoretical Study of Turbulent Oscillatory Boundary Layers written by Jing Yuan (Ph. D.) and published by . This book was released on 2013 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediment transport is of crucial importance to engineering projects in coastal regions, so it is of primary interest in coastal engineering. The driving forces for sediment transport are mostly determined by the hydrodynamics of oscillatory turbulent bottom boundary layers, which is still not well understood. Therefore, the goal of this thesis is to improve the present experimental and theoretical understandings on this subject. A high-quality experimental study including a large number of tests which correspond to full-scale coastal boundary layer flows is performed using a state-of-the-art oscillating water tunnel (OWT) for flow generations and a Particle Image Velocimetry system for velocity measurements. The experimental results suggest that the logarithmic profile can accurately represent the boundary layer flows in the very near-bottom region, so the log-profile fitting analysis can give highly accurate determinations of the hydrodynamic roughness, the theoretical bottom location and the bottom shear stress. The current velocity profiles in the presence of sinusoidal waves indicate a two-log-profile structure suggested by the widely-used Grant-Madsen model. However, for weak currents in the presence of nonlinear waves, the two-log-profile structure is contaminated or even totally obliterated by the boundary layer streaming which is related with the temporal variation of the turbulent eddy viscosity. This, together with some other experimental evidence, motivates the development of a new theoretical model which adopts a rigorous way to account for a time-varying turbulent eddy viscosity. The model accurately predicts the mean and leading Fourier components of the velocity and the bottom shear stress for various flow conditions. Most importantly, the boundary layer streaming related to the time-varying turbulent eddy viscosity is reasonably predicted, which leads to successful predictions of the mean velocity embedded in nonlinear-wave tests and the current velocity profiles in the presence of either sinusoidal or nonlinear waves. The predictions reveal significant differences between boundary layer flows in OWTs and in the coastal environment, which must be considered when interpreting OWT results for sediment transport.

Download or read book Evaluation of Wave current Bottom Boundary Layer Modelstitle written by Claire S. Nichols and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Widespread beach erosion is threatening coastal environments making coastal engineering, especially sediment transport, a rising field of interest. An improved understanding of sediment transport will help us to combat coastal threats such as beach erosion, harbor siltation, submerged object scour, and coastal structure failure. In coastal environments sediment is transported by both currents and waves. This environment is complicated because waves and currents interact in a way that does not allow for a linear sum of their separate behaviors. In this effort, the wave-current bottom boundary layer physics are examined with several applied engineering models and with a more sophisticated numerical model. The models are evaluated with the mean bed stress, a parameter used for the bottom dissipation calculations in circulation models, and the peak bed stress, a parameter used for quantifying sediment transport. The numerical model, Dune, used in these calculations is a quasi-three dimensional, non-hydrostatic numerical model. The model resolves the relevant dynamics of wave and current boundary layers over smooth and rough movable sand beds and includes models for the two modes of sediment transport, bed load and suspended load ((Fredsøe et al., 1999)). Model calculations were performed for 7 wave periods, 20 wave velocities, 10 current velocities, and 2 wave-current angles. The calculations were compared with three models currently used in engineering practice (Grant-Madsen (1994), Soulsby (1993), Styles- Glenn (2000)). Predictions of the mean and peak bed stress by Dune and the three wave-current boundary layer models are generally of comparable magnitude. However, predictions of the mean bed stress by all three engineering models diverge from Dune when the wave velocity is greater than the current velocity. An obliquely approaching current does not have a significant effect on the peak bed stress, but does affect the mean bed stress under large wave forcing. Predictions of the peak bed stress by the Grant-Madsen, and Styles-Glenn models are consistent with the Dune simulations at large wave periods, but are larger than the Dune simulations for the smaller wave periods, indicating a greater sensitivity to inertial effects produced by the waves. These results show that there exists model divergence when the unsteady wave forcing is larger than the mean forcing. This summer the models will be evaluated with field observations obtained in a large-scale wave flume.

Download or read book Shelf Sediment Transport Process and Pattern written by Donald J. P. Swift and published by . This book was released on 1973 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers presented in a symposium on Shelf Sediment Transport conducted at the annual meeting of the Geological Society of America held in Washington, D.C., November 1971.

Download or read book Turbulence In Coastal And Civil Engineering written by B Mutlu Sumer and published by World Scientific. This book was released on 2020-03-23 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the subject of turbulence encountered in coastal and civil engineering.The primary aim of the book is to describe turbulence processes including transition to turbulence; mean and fluctuating flows in channels/pipes, and in currents; wave boundary layers (including boundary layers under solitary waves); streaming processes in wave boundary layers; turbulence processes in breaking waves including breaking solitary waves; turbulence processes such as bursting process and their implications for sediment transport; flow resistance in steady and wave boundary layers; and turbulent diffusion and dispersion processes in the coastal and river environment, including sediment transport due to diffusion/dispersion.Both phenomenological and statistical theories are described in great detail. Turbulence modelling is also described, and several examples for modelling of turbulence in steady flow and wave boundary layers are presented.The book ends with a chapter containing hands-on exercises on a wide variety of turbulent flows including experimental study of turbulence in an open-channel flow, using Laser Doppler Anemometry; Statistical, correlation and spectral analysis of turbulent air jet flow; Turbulence modelling of wave boundary layer flows; and numerical modelling of dispersion in a turbulent boundary layer, a set of exercises used by the authors in their Masters classes over many years.Although the book is essentially intended for professionals and researchers in the area of Coastal and Civil Engineering, and as a text book for graduate/post graduate students, the contents of the book will, however, additionally provide sufficient background in the study of turbulent flows relevant to many other disciplines, such as Wind Engineering, Mechanical Engineering, and Environmental Engineering.

Download or read book Sediment Transport in the Coastal Environment written by Ole Secher Madsen and published by . This book was released on 1976 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of sediment transport in the coastal zone is investigated and the answers to some of the basic questions of sediment transport in unsteady, oscillatory flow are presented. By adopting Jonsson's (1966) results for the bottom shear stress associated with a simple wave motion, it is shown that Shield's criterion for the initiation of sediment movement on a flat bed holds in unsteady as well as steady flow. A simplified analysis as well as experimental data show the side effects associated with the experimental procedure in which a tray containing sediment is oscillated in still water is generally insignificant and is, therefore, a valid procedure for studying certain aspects of wave sediment interaction. Also, Shields Parameter is identified as the physically important parameter quantifying the fluid sediment interaction. An empirical relationship between a non-dimensional average sediment transport rate and Shields Parameter is found by reanalyzing the experimental data on the rate of sediment transport in oscillatory flow obtained by Einstein and co-workers at Berkeley. This relationship is similar to the Einstein-Brown sediment transport relationship in unidirectional, steady flow. By generalizing Jonsson's expression for the bottom shear stress associated with a sinusoidal wave motion, it is shown that the empirical sediment transport relationship may be derived from a quasi steady application of the Einstein-Brown sediment transport relationship. Also, it is demonstrated that the empirical relationship obtained using a friction factor based on grain roughness is capable of predicting sediment transport rates observed in experiments where bed forms were present. The general application of the derived sediment transport relationship for predicting net rates of sediment transport in the presence of second order effects such as bottom slope, wave asymmetry, mass transport currents and coastal currents is discussed. This discussion serves also to identify needed areas for future research. It is concluded that only the case of a small amplitude wave and a steady current seems to be understood to the extent that it is reasonable to evaluate the resulting sediment transport with any degree of confidence. Fortunately, this is a rather important situation in most offshore regions. A general numerical model is developed for the sediment transport and topographical changes resulting from spatially varying wave and current conditions. A simple numerical example of the evaluation of the topographical changes in the vicinity of the tip of a long straight breakwater is presented for periodic waves normally incident on the breakwater and a current parallel to the breakwater. This numerical example is chosen to resemble rather severe conditions for the Atlantic Generating Station (AGS) site with a maximum orbital wave velocity of 3.2 ft/sec (1 m/sec) and a current velocity 0.5 ft/sec (.15 m/sec). The results are.presented in a topographical relief map showing areas of scour and accretion of the order 0.78 inches/day (2 cm/day) at a maximum. Although the results of the example are somewhat more qualitative than-quantitative, it is felt that they provide a representative picture of the expected bottom changes in the vicinity of the AGS.

Download or read book Modelling and Analysis of Fine Sediment Transport in Wave Current Bottom Boundary Layer written by Liqin Zuo and published by CRC Press. This book was released on 2018-06-19 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. This thesis aims to better understand fine sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL). Field observations, experimental data analysis, theoretical analysis and numerical models are employed. Silt-dominated sediments are sensitive to flow dynamics and the suspended sediment concentration (SSC) increase rapidly under strong flow dynamics. This research unveils several fundamental aspects of silty sediment, i.e., the criterion of the incipient motion, the SSC profiles and their phase-averaged parameterization in wave-dominated conditions. An expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. A process based intra-wave 1DV model for flow-sediment dynamics near the bed is developed in combined wave-current conditions. The high concentration layer (HCL) was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the SSC in the HCL. Finally, based on the 1DV model, the formulations of the mean SSC profile of silt-sand sediments in wave conditions were proposed. The developed approaches are expected to be applied in engineering practice and further simulation.

Download or read book Waves on Beaches and Resulting Sediment Transport written by Richard E. Meyer and published by . This book was released on 1972 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bottom Sediment Transport written by Donald Ormond Hodgins and published by . This book was released on 1986 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediment transport and soil liquefaction under wave loading are major concerns for offshore hydrocarbon developments in Canadian waters. This report presents a state-of-the-art review of five topics concerned with seabed mobility and liquefaction, together with a summary of research priorities to address a number of outstanding problems facing the offshore industry. The review deals with sediment transport produced by waves and currents without structures such as pipelines or platform footings present to modify the flow. Thus such topics as localized scour around structures are not considered.