Surf-zone Hydrodynamics


Book Description




Advances In Coastal And Ocean Engineering, Vol 2


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.




Advances in Coastal and Ocean Engineering


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.




Shore Wave Modulation Due to Infragravity Waves in the Nearshore Zone, with Applications


Book Description

The omni-present low frequency wave motion (30-300 sec) contains a substantial fraction of the total wave energy inside the surf zone. A more complete description of nearshore wave processes considers incident short period waves superposed on, and interacting with, long standing waves. The wind waves are modulated in amplitude, wavenumber and direction due to relatively slowly varying depth changes caused by the long waves. The energy in the wind wave band is enhanced by side band growth at the sum and difference frequencies of short and long waves (order 15% at the shoreline). The modulation is identified in the analysis of field data as a positive correlation between the long waves and the wind wave envelope near the shoreline. Considering oblique incident waves, a steady longshore current showing a non-vanishing current at the shoreline is found as a result of the non-linear interaction between monochromatic incident and infragravity waves. An analytical solution describing the unsteadiness of the longshore current is developed. Keywords include: Infragravity, Longshore Current, Sediment transport, and Surf zone dynamics. (Theses).




Infragravity Waves in the Nearshore Zone


Book Description

This report summarizes the present state of knowledge on infragravity wave motions (nominally 0.003 to 0.05 Hz). Theoretical and observational studies are presented. Most of the studies discussed herein have been published elsewhere, however a few studies discussed in chapter 4 are presented for the first time in this report Measurements of nearshore waves and currents have shown that a significant amount of the total energy can be contained in the infragravity band, and on highly dissipative beaches the infragravity wave variance often dominates over energy in the incident wave band(0.05 to 0.3 Hz). An 8-month data set of infragravity variance measured at 8-m-depth at the shoreline (runup) was compared with incident wave variance. Analysis of the 8-m-depth data showed that high mode edge waves account for about 50 percent of the total infragravity variance, and as high as 80 percent at times. Significant edge wave heights greater than 20 cm were observed at the 8-m depth. Infragravity wave variance was shown to have a higher correlation with swell variance (C = 0.95) than with sea variance (C = 0.61). This report was motivated, in part, by the need to determine the significance of infragravity waves on coastal erosion and structure damage and by the desire to improve coastal engineering solutions to problems associated with nearshore processes.







Measuring Ocean Currents


Book Description

Measuring Ocean Currents: Tools, Technologies, and Data covers all major aspects of ocean current measurements in view of the implications of ocean currents on changing climate, increasing pollution levels, and offshore engineering activities. Although more than 70% of the Earth is covered by ocean, there is limited information on the countless fine- to large-scale water motions taking place within them. This book fills that information gap as the first work that summarizes the state-of-the-art methods and instruments used for surface, subsurface, and abyssal ocean current measurements. Readers of this book will find a wealth of information on Lagrangian measurements, horizontal mapping, imaging, Eulerian measurements, and vertical profiling techniques. In addition, the book describes modern technologies for remote measurement of ocean currents and their signatures, including HF Doppler radar systems, satellite-borne sensors, ocean acoustic tomography, and more. Crucial aspects of ocean currents are described in detail as well, including dispersion of effluents discharged into the sea and transport of beneficial materials—as well as environmentally hazardous materials—from one region to another. The book highlights several important practical applications, showing how measurements relate to climate change and pollution levels, how they affect coastal and offshore engineering activities, and how they can aid in tsunami detection. - Coverage of measurement, mapping and profiling techniques - Descriptions of technologies for remote measurement of ocean currents and their signatures - Reviews crucial aspects of ocean currents, including special emphasis on the planet-spanning thermohaline circulation, known as the ocean's "conveyor belt," and its crucial role in climate change







Coastal Dynamics '95


Book Description

Ninety-two proceedings papers from the 1995 conference reviewing large-scale field and laboratory experiments in the European Community, Japan, the US, and the former Soviet-Bloc countries of Russia, Bulgaria, East Germany, and Poland. These volume particularly features the discussions from those latter countries since most of their experiments have not been, until now, released to the West. In more specific terms, the papers report findings in wave motion in vegetated and non-vegetated coastal zone, surf zone modeling, planform considerations of beach nourishment, swash dynamics, runup, low- frequency motion, longshore currents, cross-shore transport, and profile evolution. Annotation copyright by Book News, Inc., Portland, OR