Advances in Coastal and Ocean Engineering

The following sections are included:

• PREFACE TO THE REVIEW SERIES

• PREFACE TO THE THIRD VOLUME

• CONTRIBUTORS

• CONTENTS

The basic theory of internal solitary waves is developed, with the main emphasis on applications to observations in coastal seas, fjords, lakes, and in the atmospheric boundary layer. Starting with the equations of motion for an inviscid, incompressible density-stratified fluid, we indicate how various asymptotic models for weakly nonlinear waves are derived, including the well-known Korteweg-de Vries equation. We then describe the solitary wave solutions, and relate their properties to applications. Various extensions are then considered which take into account such effects as friction, variable background environment, wave refraction, finite-amplitude effects and specific generation mechanisms.

There are some overall similarity laws in wind waves in the ocean. A conspicuous one is expressed by the 3/2-power law. In windsea generation areas, which are rather free of swells, the significant wave height can be given as a joint function of the wind speed and the significant wave period. The maximum steepness is given as a function of the wave age. This article gives a general review of this law; its observational basis; a discussion of the physical background, especially the friction-velocity proportionality and the self-adjustment processes to attain it; and finally perturbations of the 3/2-power law due to gustiness or swells. Applications of this law are also given as a test criterion for the wind-windsea equilibrium conditions, and in ocean wave modeling.

The concept of directional wave spectrum is introduced with a historical overview of its development. Standard formulas of directional spreading function for engineering applications are then presented, based on the information obtained through ocean measurements. Several features of random waves specified with directional spectra are discussed, including the statistical properties of wave crest lengths. Reviews are made on numerical methods for analyzing transformations of directional random waves in shoaling waters. The effects of directional spreading on long waves, nearshore currents, and wave forces on structures are also reviewed. The paper concludes with a discussion of multidirectional wave basins which have become one of the standard facilities in hydraulic laboratories around the world.

The inherent drawbacks of several conventional methods for estimating the directional wave spectrum are discussed, after which three of the most practical methods are described: the maximum entropy principle method (MEP), Bayesian directional spectrum estimation method (BDM), and extended maximum entropy principle method (EMEP). Numerical computation procedures for these methods are described in some details. These methods are examined using numerical simulation and field data of waves, with their validity being subsequently discussed. In addition, a newly developed submerged Doppler-type directional wave meter is introduced with an example of directional spectra obtained.

The objective of this paper is to introduce the application of reliability theory for conceptual design and evaluation of coastal structures. It is without the scope to discuss the validity and quality of the various design formulae available for coastal structures. The contents of the paper is a combination of material presented in the following references: Burcharth, H.F. (1992) Reliability evaluation of a structure at sea. Proceedings of the Short. Course on Design and Reliability of Coastal Structures. Venice, Scuola di S. Giovanni Evangelista, 1992. 23rd International Conference on Coastal Engineering. Burcharth, H.F. (1993) Design of Breakwaters. Aalborg University. Department of Civil Engineering. Aalborg, Denmark. (Note). Burcharth, H.F., Dalsgaard Sørensen, J., Christiani, E. (1995) Application for reliability analysis for optimal design of monolithic vertical wall breakwaters. Proceedings Conference of Port and Coastal Engineering in developing countries. Rio de Janeiro, Brazil, 1995.