A computerized method for the identification of wave groups and determination of their properties from digital wave data was developed. Analysis was performed on 208 Southern California wave records. It was found that the number of waves in a group is independent of both the spectral peak period and the variance of the wave record. However, the amount of energy contained in wave groups relative to that in the record increases as the total energy of the record increases. Also, average group periods of greater than the spectral peak period are not uncommon. Both an increase in group energy relative to the wave record and also the number of waves in a group increase the possibility of obtaining an extreme wave height in a group relative to the significant wave height of the record. Finally, it is apparent that as the average group period approaches the spectral peak period of a record, all other highly dependent wave group properties take on their maximum values. (Author).

Extreme, freak or rogue waves are produced by a number of physical mechanisms that focus the water-wave energy into a small area, due to wave instability, chaotic behaviour, dispersion (frequency modulation), refraction (presence of variable currents or bottom topography), soliton interactions, etc. During the past thirty years a number of physical models of the rogue wave phenomenon have been intensively developed. Numerous experimental, statistical and theoretical investigations are intended to understand the physics of the huge wave formation, its relation to the environmental conditions and to provide a freak wave design for engineering purposes. The book details the vast progress that has been achieved in the understanding of the physical mechanisms of rogue wave phenomenon in recent years. The selected articles address such issues as the formation of freak waves due to modulation instability of nonlinear wave field, physical and statistical properties of rogue wave generation in deep water and in shallow water, various models of nonlinear water waves, special analysis of nonlinear resonances between water waves and the relation between observations and freak wave theories. The book is written for specialists in the fields of fluid mechanics, applied mathematics, nonlinear physics, physical oceanography and geophysics, and for students learning these subjects.

Waves observed in the ocean are extremely irregular and, from a physics standpoint, it seems impossible to describe this chaotic situation. Scientists can describe the situation by means of a stochastic approach. This book describes the stochastic method for ocean wave analysis. This method provides a route to predicting the characteristics of random ocean waves--information vital for the design and safe operation of ships and ocean structures. Assuming a basic knowledge of probability theory, the book begins with a chapter describing the essential elements of wind-generated random seas from the stochastic point of view. The following three chapters introduce spectral analysis techniques, probabilistic predictions of wave amplitudes, wave height and periodicity. A further four chapters discuss sea severity, extreme sea state, the directional wave energy spreading in random seas and special wave events such as wave breaking and group phenomena. Finally the stochastic properties of non-Gaussian waves are presented. Useful appendices and an extensive reference list are included. Examples of practical applications of the theories presented can be found throughout the text. This book will be suitable as a text for graduate students of naval, ocean and coastal engineering. It will also serve as a useful reference for research scientists and engineers working in this field.

Wave Mechanics and Wave Loads on Marine Structures provides a new perspective on the calculation of wave forces on ocean structures, unifying the deterministic and probabilistic approaches to wave theory and combining the methods used in field and experimental measurement.Presenting his quasi-determinism (QD) theory and approach of using small-scale field experiments (SSFEs), author Paolo Boccotti simplifies the findings and techniques honed in his ground-breaking work to provide engineers and researchers with practical new methods of analysis. Including numerous worked examples and case studies, Wave Mechanics and Wave Loads on Marine Structures also discusses and provides useful FORTRAN programs, including a subroutine for calculating particle velocity and acceleration in wave groups, and programs for calculating wave loads on several kinds of structures. Solves the conceptual separation of deterministic and stochastic approaches to wave theory seen in other resources through the application of quasi-determinism (QD) theory Combines the distinct experimental activities of field measurements and wave tank experiment using small-scale field experiments (SSFEs) Simplifies and applies the ground-breaking work and techniques of this leading expert in wave theory and marine construction