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Author: Dennis James Whitford
Publisher:
ISBN:
Category : Banks (Oceanography)
Languages : en
Pages : 238
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Book Description
Previous investigations of longshore currents have included simplifying assumptions and restriction (such as a planar beach, a steady and depth uniform flow, spatially-variant bed shear stress and turbulent momentum exchange, and the exclusion of surface wind stress. These assumptions are quantitatively investigated by calculating the relative importance of each term in the longshore momentum balance with an emphasis on the relative importance of wind forcing across the barred nearshore. Wind and wave forcing of longshore currents across a barred beach are examined using both a numerical model and field measurements. A local momentum balance was measured at various locations across the surf zone during the SUPERDUCK experiment held at the USACE CERC Field Research Facility, Duck, N.C. in October 1986. A moveable sled was instrumented with pressure, current, and wind sensors to measure the various terms in the longshore momentum equation. Stability-dependent atmospheric drag coefficients for the surf zone are determined from wind stress measurements acquired just beyond the surf zone and wind speed measurements acquired from an anemometer atop the 9 m sled mast. Breaking waves were visually identified and electronically marked on the data tapes. Keywords: Ocean currents; Air water interactions; Nearshore surf zone; Wind stress; Theses. (EDC).
Author: Dennis James Whitford
Publisher:
ISBN:
Category : Banks (Oceanography)
Languages : en
Pages : 238
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Book Description
Previous investigations of longshore currents have included simplifying assumptions and restriction (such as a planar beach, a steady and depth uniform flow, spatially-variant bed shear stress and turbulent momentum exchange, and the exclusion of surface wind stress. These assumptions are quantitatively investigated by calculating the relative importance of each term in the longshore momentum balance with an emphasis on the relative importance of wind forcing across the barred nearshore. Wind and wave forcing of longshore currents across a barred beach are examined using both a numerical model and field measurements. A local momentum balance was measured at various locations across the surf zone during the SUPERDUCK experiment held at the USACE CERC Field Research Facility, Duck, N.C. in October 1986. A moveable sled was instrumented with pressure, current, and wind sensors to measure the various terms in the longshore momentum equation. Stability-dependent atmospheric drag coefficients for the surf zone are determined from wind stress measurements acquired just beyond the surf zone and wind speed measurements acquired from an anemometer atop the 9 m sled mast. Breaking waves were visually identified and electronically marked on the data tapes. Keywords: Ocean currents; Air water interactions; Nearshore surf zone; Wind stress; Theses. (EDC).
Author: Antonio Fernando Garcez Faria
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 182
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Book Description
The objective of this dissertation is to develop numerical models and compare their predictions with data acquired during the DUCK94 experiment in order to improve our physical understanding of the hydrodynamic processes governing the vertical and cross shore distributions of both longshore and cross shore currents over a barred beach. The vertical structure of the mean longshore current is found to be well described by a logarithmic profile and a relationship between bed shear stress and bottom roughness, including the influence of ripples and mega-ripples, was also found. The vertical structure of the mean cross shore current (undertow) is modeled using an eddy viscosity closure scheme to solve for the turbulent shear stress and includes contributions from breaking wave rollers. These models of the vertical profiles of longshore and cross shore mean currents are combined to formulate a quasi three dimensional model to describe the cross shore distribution of the longshore current. This model includes turbulent mixing due to the cross shore advection of mean momentum of the longshore current by the mean cross shore current and contributions from wave rollers.
Author: Philip L. F. Liu
Publisher: World Scientific
ISBN: 9810224109
Category : Technology & Engineering
Languages : en
Pages : 290
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Book Description
This volume contains six papers discussing coastal processes, and physical and numerical modeling.In the first paper, Svendsen and Putrevu give an extensive review on the state of understanding of surf-zone hydrodynamics, including subjects such as wave breaking, wave-induced currents, and instability of nearshore currents and infragravity waves. They point out that the most urgent need is to develop an adequate theory for wave breaking and broken waves in the surf zone.One of the methods for studying the complex coastal processes is to perform laboratory experiments. However, physical models are always plagued by scale and laboratory effects, because the coastal process involves many different length and time scales. In the second paper, Kamphuis presents a detailed discussion on the sources and implications of the scale and laboratory effects on physical modeling.The third and the fourth papers are two parts of the discussion on the mathematical modeling of the meso-tidal barrier island coasts. To understand the dynamics of coastal inlet systems, one can either rely on empirical knowledge and construct various forms of empirical and semi-empirical models (Part I), or develop a set of mathematical models based on the physical processes (Part II). Although these models do not provide the details of the dynamics, they give valuable knowledge of the equilibrium-state relationships. de Vriend and Ribberink give a detailed review on two models, Initial Sedimentation/Erosion models and Medium-Term Morphodynamic models. They have also presented many examples of applications.In the fifth paper, Houston gives a brief review on different methods to mitigate beach loss caused by storms or persistent long-term erosion. He then describes, in detail, the method of beach nourishment, which is also called a beach fill. This paper discusses the information that must be collected to design a beach fill and that should be monitored after the completion of the project.The last paper of this volume shifts our attention to the design of offshore structures, such as gravity structures, floating barges and tankers. Chakrabarti discusses the effects of the uniform and shear currents on fixed and floating structures.
Author: Philip L-f Liu
Publisher: World Scientific
ISBN: 9814499838
Category : Technology & Engineering
Languages : en
Pages : 290
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Book Description
This volume contains six papers discussing coastal processes, and physical and numerical modeling.In the first paper, Svendsen and Putrevu give an extensive review on the state of understanding of surf-zone hydrodynamics, including subjects such as wave breaking, wave-induced currents, and instability of nearshore currents and infragravity waves. They point out that the most urgent need is to develop an adequate theory for wave breaking and broken waves in the surf zone.One of the methods for studying the complex coastal processes is to perform laboratory experiments. However, physical models are always plagued by scale and laboratory effects, because the coastal process involves many different length and time scales. In the second paper, Kamphuis presents a detailed discussion on the sources and implications of the scale and laboratory effects on physical modeling.The third and the fourth papers are two parts of the discussion on the mathematical modeling of the meso-tidal barrier island coasts. To understand the dynamics of coastal inlet systems, one can either rely on empirical knowledge and construct various forms of empirical and semi-empirical models (Part I), or develop a set of mathematical models based on the physical processes (Part II). Although these models do not provide the details of the dynamics, they give valuable knowledge of the equilibrium-state relationships. de Vriend and Ribberink give a detailed review on two models, Initial Sedimentation/Erosion models and Medium-Term Morphodynamic models. They have also presented many examples of applications.In the fifth paper, Houston gives a brief review on different methods to mitigate beach loss caused by storms or persistent long-term erosion. He then describes, in detail, the method of beach nourishment, which is also called a beach fill. This paper discusses the information that must be collected to design a beach fill and that should be monitored after the completion of the project.The last paper of this volume shifts our attention to the design of offshore structures, such as gravity structures, floating barges and tankers. Chakrabarti discusses the effects of the uniform and shear currents on fixed and floating structures.
Author: Cheryl E. Pollock
Publisher:
ISBN:
Category : Barbers Point Harbor (Hawaii)
Languages : en
Pages : 130
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Book Description
Author: Jane Mckee Smith
Publisher: World Scientific
ISBN: 9814467561
Category : Technology & Engineering
Languages : en
Pages : 5136
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Book Description
This proceedings contains papers presented at the 31st International Conference on Coastal Engineering, which has held in Hamburg, Germany (31 August - 5 September 2008). The proceeding is divided into five parts: Waves; Long Waves, Nearshore Currents, and Swash; Sediment Transport and Morphology; Coastal Management, Environment, and Risk; and Coastal Structures. The papers cover a broad range of topics including theory, numerical and physical modeling, field measurements, case studies, design, and management. Coastal Engineering 2008 provides coastal engineers, scientists, and planners, with state-of-the-art information on coastal engineering and coastal processes.
Author:
Publisher:
ISBN:
Category : Coastal engineering
Languages : en
Pages : 300
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Book Description
Author: Waterways Experiment Station (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 122
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Book Description
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 516
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Book Description
Author: Edward J. Anthony
Publisher: Elsevier
ISBN: 0080558860
Category : Science
Languages : en
Pages : 540
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Book Description
The last five years have been marked by rapid technological and analytical developments in the study of shore processes and in the comprehension of shore deposits and forms, and shoreline change over time. These developments have generated a considerable body of literature in a wide range of professional journals, thus illustrating the cross-disciplinary nature of shore processes and the palaeo-environmental dimension of shore change. The justification of the book lies in bringing together these developments using an objective approach that synthesises current advances, technical progress in the analysis of shores and shore processes, contradictory interpretations, and potential advances using future-generation developments in techniques. The book provides a comprehensive state-of-the-art presentation of shore processes and deposits across ranges of wave energy and tide-range environments, sediment supply and textural conditions, sea-level change, exceptional events and longer-term climate change, based on the most recently published literature in the marine sciences. The book insists on the nested time and spatial scales through which are inter-linked shore processes and deposits, thus providing a better understanding of the way shores change over time. The approach is thus cross-disciplinary, and gap-bridging between processes and deposits, between analytical techniques, and between timescales. The audience is from graduate level upwards, and the book is intended as a comprehensive reference source for professionals in a wide range of coastal science fields (geologists, sedimentologists, geomorphologists, oceanographers, engineers, managers, archaeologists...).* Aimed at graduates and specialists interested in coastal science* Presents background research, recent developments and future trends* Written by a leading scholar and industry expert
