Topics in Longshore Currents
Topics in Longshore Currents

Author: John Casey Church

Publisher:

Published: 1993

Total Pages: 140

ISBN-13:

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The momentum equation governing mean longshore currents on straight beaches is a balance of forcing from the momentum transfer of the oscillatory wave motion, turbulent momentum transfer (mixing), and bottom stress. Of these, the wave's contribution is well understood, but the remaining two are not, principally due to the complicated hydrodynamics of the surf-zone. Addressing the bottom stress term, a longshore current model is developed which includes a modification of the bottom stress due to the effects of breaking-wave induced turbulence. A one-dimensional turbulent kinetic energy equation is used to model this breaking-wave induced turbulence, producing a spatially varying bottom friction coefficient. The modeled longshore current cross-shore profiles show improved agreement with field observations. In a second bottom stress study, vertical profiles of mean longshore currents are examined using field data obtained with vertically stacked electromagnetic current meters with the goal of measuring the bottom stress and its associated drag coefficient. The profiles are observed to become vertically uniform whenever the ratio of wave height to depth exceeds 0.3, indicating that nearly all of the waves passing a given location are breaking. Finally, horizontal turbulent momentum transfer (mixing) is examined for the case of shear instabilities of the longshore current.

Basic Coastal Engineering
Basic Coastal Engineering

Author: Robert Sorensen

Publisher: Springer Science & Business Media

Published: 2013-03-14

Total Pages: 311

ISBN-13: 1475726651

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In the 20 years since publication of the first edition of this book there have been a number of significant changes in the practice of coastal engineering. This new edition has been completely rewritten to reflect these changes as well as to make other improvements to the material presented in the original text. _ Basic Coastal Engineering is an introductory text on wave mechanics and coastal processes along with the fundamentals of the practice of coa~tal engi neering. This book was written for a senior or first postgraduate course in coastal engineering. It is also suitable for self study by anyone having a basic engineering or physical science background. The level of coverage does not require a math or fluid mechanics background beyond that presented in a typical undergraduate civil or mechanical engineering curriculum. The material presented in this text is based on the author's lecture notes from a one-semester course at Virginia Pol ytechnic Institute, Texas A&M University, and George Washington University, and a senior elective course at Lehigh University. The text contains examples to demonstrate the various analysis techniques that are presented and each chapter (except the first and last) has a collection of problems for the reader to solve that further demonstrate and expand upon the text material. Chapter 1 briefly describes the coastal environment and introduces the rela tively new field of coastal engineering.

Physical Oceanography of Coastal and Shelf Seas
Physical Oceanography of Coastal and Shelf Seas

Author: B. Johns

Publisher: Elsevier

Published: 1983-01-01

Total Pages: 483

ISBN-13: 0080870732

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This book provides a thorough treatment of both theoretical and observational aspects of the interaction between the sea-floor and the near-sea-floor dynamics; the effect this has on the distribution of internal and seabed stress; and the relevance of the associated dynamics to sedimentation processes. The theoretical work described involved both analytical and numerical modelling studies of a wide range of near-shore and shelf processes. These provide a valuable store of information on the interaction between the sea-floor and the dynamics of the overlying water. The book also includes an account of tidal analysis techniques and how these are being applied in the analysis of tidal current measurements. The observational studies relate to measurements of near-sea-floor turbulence and sand-transport in the littoral zone.

Sandy Beach Morphodynamics
Sandy Beach Morphodynamics

Author: Derek Jackson

Publisher: Elsevier

Published: 2020-05-19

Total Pages: 816

ISBN-13: 0081029284

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Sandy beaches represent some of the most dynamic environments on Earth and examining their morphodynamic behaviour over different temporal and spatial scales is challenging, relying on multidisciplinary approaches and techniques. Sandy Beach Morphodynamics brings together the latest research on beach systems and their morphodynamics and the ways in which they are studied in 29 chapters that review the full spectrum of beach morphodynamics. The chapters are written by leading experts in the field and provide introductory level understanding of physical processes and resulting landforms, along with more advanced discussions. - Includes chapters that are written by the world's leading experts, including the latest up-to-date thinking on a variety of subject areas - Covers state-of-the-art techniques, bringing the reader the latest technologies/methods being used to understand beach systems - Presents a clear-and-concise description of processes and techniques that enables a clear understanding of coastal processes