Breaking Wave Spectrum in Water of Finite Depth in the Presence of Current


Book Description

This report presents an approximate method to compute the mean value, the mean-square value, and the spectrum of waves in water of finite depth taking into account the effect of wave breaking in the presence of current. It is assumed that there exists a linear and Gaussian ideal wave train whose spectrum is first obtained using the wave energy flux balance equation without considering wave breaking. The Miche wave breaking criterion for waves in finite water depth is used to limit the wave elevation and establish an expression for the breaking wave elevation in terms of the elevation and its second time derivative of the ideal waves. Simple expressions for the mean value, the mean-square value and the spectrum are obtained. These results are applied to the case in which a deepwater unidirectional wave train, propagating normally toward a straight shoreline over gently varying sea bottom of parallel and straight contours, encounters an adverse steady current whose velocity is assumed to be uniformly distributed with depth. Numerical results are obtained and presented in graphic form.







A Columbia River Entrance Wave Forecasting Program Developed at the Ocean Products Center


Book Description

This report describes the OPC spectral wave forecasting model for the Columbia River Bar, as well as the results of some numerical experiments, on both micro and main frame computers. The model, essentially, calculates the transformation of offshore wave spectra forecasted by the OPC global wave model due to the combined effects of bottom topography and tidal currents in the vicinity of the Columbia River entrance.













Extreme Ocean Waves


Book Description

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.