Search

The opportunity of using wave energy converter arrays in a hot spot area of the Mediterranean sea was investigated. For this purpose, numerical simulations of wave energy converters together with a simple cost-effective analysis were carried out. The selected study area is one of the most energetic inside the Sicilian channel (Italy). The numerical simulations were performed using the SNL-SWAN ("Sandia National Laboratories – Simulating WAves Nearshore") spectral model with an unstructured mesh. The power absorbed from thirteen Wave Energy Converter (WEC) devices was computed. In particular, Pelamis, Wave Dragon, Oyster 2, Wavestar, B-HBA, B-OF, Bref-HB, Bref-SHB, F–2HB, F–3OF, F-HBA and F-OWC were investigated. Hydrodynamic stationary simulations of a WEC array parallel to the coastline were carried out in order to choose the best devices for a non-stationary simulation. The devices selected for this simulation are Pelamis, Wave Dragon, Oyster 2, F–2HB, and Bref-HB. The non-stationary simulation was forced with thirty-nine years wave parameters reanalysis from ERA5 by ECMWF (European Centre for Medium-range Weather Forecasts). This simulation has allowed to obtain the capacity factor (CF) and the dissipative effects in the period from 1979 to 2018. Moreover, a preliminary cost-to-benefit analysis was carried out for the best performance WEC array only. Costs, revenues, LCoE (Levelized Cost of Energy), and payback period were therefore computed by means of economic assumptions. The high energy concentration near the coast produces hydrodynamic effects which have as a consequence potential erosion phenomena. A shoreline change analysis of three beaches of the studied coast was carried out. Such an analysis was focused on shoreline retreatment during the last thirty years. On the basis of the presented results, there is a slight economic advantage in installing a Wave Dragon scaled array with the added value of potentially giving beneficial effects on coastal erosion. Nevertheless, from a strictly economic point of view, other renewable resources could give better results (e.g. wind energy). The adopted methodology gives encouraging results that confirm the opportunity to deploy WEC devices in the Sicilian Channel together with devices exploiting other renewable resources. [ABSTRACT FROM AUTHOR]

We extend a recently proposed 2D depth-integrated Finite Volume solver for the nonlinear shallow water equations with non-hydrostatic pressure distribution. The proposed model is aimed at simulating both nonlinear and dispersive shallow water processes. We split the total pressure into its hydrostatic and dynamic components and solve a hydrostatic problem and a non-hydrostatic problem sequentially, in the framework of a fractional time step procedure. The dispersive properties are achieved by incorporating the non-hydrostatic pressure component in the governing equations. The governing equations are the depth-integrated continuity equation and the depth-integrated momentum equations along the x, y and z directions. Unlike the previous non-hydrostatic shallow water solver, in the z momentum equation, we retain both the vertical local and convective acceleration terms. In the former solver, we keep only the local vertical acceleration term. In this paper, we investigate the effects of these convective terms and the possible improvements of the computed solution when these terms are not neglected in the governing equations, especially in strongly nonlinear processes. The presence of the convective terms in the vertical momentum equation leads to a numerical solution procedure, which is quite different from the one of the previous solver, in both the hydrostatic and dynamic steps. We discretize the spatial domain using unstructured triangular meshes satisfying the Generalized Delaunay property. The numerical solver is shock capturing and easily addresses wetting/drying problems, without any additional equation to solve at wet/dry interfaces. We present several numerical applications for challenging flooding processes encountered in practical aspects over irregular topography, including a new set of experiments carried out at the Hydraulics Laboratory of the University of Palermo. [ABSTRACT FROM AUTHOR]

Shoreline evolution studies are fundamental to assess the rate of beach accretion or retreatment. In the last years, researchers developed many methods with several techniques belonging to different disciplines and backgrounds. Nowadays, the Shoreline Change Analysis (SCA) is the most widespread method to assess shoreline evolution. In fact, the SCA is needed to perform management strategies able to respond to current erosion or potential future erosion problems. This paper presents a new approach using an automatic method for SCA with accuracy and speed improvements. Indeed, in the framework of the management of coastal erosion and to develop an adaptation plan to coastal hazards it is necessary to study the links existing between coastal and marine morphological transformations. A new tool was written in Matlab, the input files were built using a GIS environment and the results were arranged in a GIS project. The present tool adopts two approaches: the Transect Based Analysis (TBA) and the Area Based Analysis (ABA). New roughness and irregularity indexes were defined to calculate the transects' spacing. Moreover, a piecewise polynomial baseline was defined to improve accuracy in shoreline position assessment. The approaches TBA and ABA were validated both by synthetic benchmarks and by a study case. The adopted synthetic benchmarks represent very common types of beaches: with one or more salients, with cusps and groynes. The case study was a logarithmic spiral Mediterranean beach on the southwestern coast of Sicily. All the studied test cases provided good results in terms of accuracy and easiness of use. The new tool and methodology, with TBA and ABA coupling, encloses many practical aspects. Indeed, ABA allows the general assessment of advancing/retreating beach areas, whereas TBA is needed to study very short stretches of beach. The proposed SCA analysis is useful for the requirements of a complete coastal management plan and to evaluate erosion management options. Moreover, the SCA gives a sound technical understanding of the physical coastal processes and should engage the community, the stakeholders and the agencies responsible for development application decisions. The new approach gives high-quality results achieved with significant speediness making it suitable for regional studies and directly providing parameters needed for erosion managing strategies. [ABSTRACT FROM AUTHOR]

Abstract: A physically based strategy was used to model swash zone hydrodynamics forced by breaking waves within a Boussinesq type of model. The position and the velocity of the shoreline were determined continuously in space by solving the physically-based equations of the shoreline motion; moreover, a fixed grid method, with a wet–dry interface, was adopted for integrating the Boussinesq model. The numerical stability of the model was improved by means of an extrapolation method. To validate the proposed methodology, the classical analytical solution for the shoreline motion of a monochromatic wave train over a plane beach was considered. The comparison between the analytical and numerical horizontal shoreline movements provided a very good agreement. Several other tests on the run-up of non-breaking and breaking waves were performed as well. These tests showed that the proposed model was always in fairly good agreement with the experimental data, even in complex hydrodynamic situations like those forced by breaking solitary waves. In particular, in comparison with other state-of-the-art shoreline models, in all the analyzed cases the proposed model allowed much better predictions of the shoreline velocity to be obtained. [Copyright &y& Elsevier]