Advances in Coastal and Ocean Engineering

The following sections are included:

• PREFACE TO THE REVIEW SERIES

• PREFACE TO THE SIXTH VOLUME

• CONTRIBUTORS

• CONTENTS

This is a completely revised chapter of the author's previous paper (Horikawa, 1996) regarding the history and heritage of coastal engineering in Japan. In the initial part of this paper, the specific cultural background of Japan will be described briefly from the viewpoint of natural conditions such as the geographical and meteorological environments of the Japanese Islands. The era of Japanese history is conventionally divided into the following three periods by considering the activities of coastal development. These are (1) Early times to Meiji Restoration, 1868, (2) Meiji Restoration to the End of World War II (1945), and (3) Postwar to the present. Coastal utilization has been actively carried out throughout the long history of Japan; however, real coastal engineering in Japan started in 1953 after the storm surge damage at Ise Bay due to Typhoon No. 13. Therefore, the contents of this paper are mainly related to achievements in the period after 1953.

The following sections are included:

• Introduction
  • Brief Remarks on Notations

• Continuous Wavelet Transform
  • Wavelet transform properties
    • Invariance
    • Redundancy
    • Time-frequency resolution
    • Scaling function
  • Examples of wavelets
    • Morlet wavelet
    • Mexican-hat wavelet
    • 8th derivative of Gaussian wavelet
    • Paul Wavelet
    • Meyer wavelet
    • Haar wavelet
    • French-hat wavelet
  • Examples of wavelet transforms

• Wavelet Spectrum Analysis
  • Cross wavelet spectrum analysis
  • Rotary wavelet spectrum analysis

• Applications of Wavelet Spectrum Analysis
  • The significance of the frequency spectrum
  • Wave grouping effects
  • Implications of stationarity
  • Wind wave growth process
  • Wind wave breaking process
  • Rotary wavelet spectrum of currents

• Concluding Remarks

• References

Nonlinear energy transfer is a dominant process in the shoaling region which culminates as the waves approach the beach. This paper considers dispersive gravity waves in water of intermediate depth. Three-wave resonance cannot occur on an even bottom. We clarify the role of depth variation in the resonant stochastic nonlinear energy transfer. Assuming a quasi-Gaussian sea, the theory of weak turbulence provides the closure for stochastic nonlinear shoaling models. The resonant interaction of a wave trio with the bottom is demonstrated for the special case of an oscillatory bathymetry. Considering the bottom oscillation as a fourth member in a resonant quartet leads to the same results that are obtained from the stochastic nonlinear shoaling model. For steep waves in shallow water, nonlinear dispersion and phase locking lead to trio interaction even on an even bottom. The rigorous study of this mechanism and its importance has yet to be pursued.

The study of oscillatory sheet flow has attracted much interest among coastal engineers because a large amount of sand is transported under this mode. Sheet flow is a grain-fluid mixture flow of high concentration under periodically varying shear stress. In order to clarify the constitutive behaviors and inner mechanics, fundamental studies have been conducted. As for the numerical studies, various kinds of advanced models have been proposed to predict the sediment velocity, concentration and transport rate. Meanwhile, the experimental studies have provided many useful findings, and they have been accumulated during the last two decades. In this paper, the recent developments in the above aspects of studies are reviewed and needs for further research are identified.

This paper reviews the application of optical techniques for the study of wave kinematics in the laboratory. Both the point method of Laser Doppler Anemometry and the whole field approach known as Particle Image Velocimetry are described, and the most important aspects relating to their practical application in wave measurement are discussed. Specific examples are given where they have been applied to the study of wave and current interaction, breaking waves, wave boundary layers and the motion of bed sediment. The technique of Laser-Induced Fluorescence, for the measurement of concentration, is described with specific reference to its application in the study of internal waves.