The Effect Of Breaking Waves On The Directional Spectrum Of Waves In Water Of Variable Depth In The Presence Of Current

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.

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.

Progress in Renewable Energies Offshore includes the papers presented in the 2nd International Conference on Renewable Energies Offshore (RENEW2016, Lisbon, Portugal, 24-26 October 2016). The scope of the book is broad, covering all aspects of renewable energies offshore activities such as resource assessment; wind energy; wave energy; tidal energy; ocean energy devices; multiuse platforms; PTO design; grid connection; economic assessment; installation and maintenance planning. The contents of the present book are organized in these main subject areas corresponding to the sessions in the Conference. The conference reflects the importance of the renewable energies offshore worldwide and is an opportunity to contribute to the exchange of information on the developments and experience obtained in concept development, design and operation of these devices. Progress in Renewable Energies Offshore has as main target academics and professionals working in the related areas of renewable energies.