Maritime Hazards

In recent years, the interest in developing new technologies to produce energy with low environmental impact by using renewable sources has grown exponentially all over the world. In this context, the experiences made to derive electricity from the sea (currents, waves, etc.) are of particular interest. At the moment, due to the many existing experiments completed or still in progress, it is quite impossible explain what has been obtained but it is worth mentioning the EMEC, which summarizes the major projects in the world. Another important environmental aspect, also related to the maritime field, is the coastal protection from the sea waves. Even in this field, since many years, the structural and non-structural solutions which can counteract this phenomenon are analyzed, in order to cause the least possible damage to the environment. The studies in development by the researchers of the University of Salerno are based on these two aspect previously presented. Considering the technologies currently available, a submerged system has been designed, WECPOS (Wave Energy Coastal Protection Oscillating System), to be located on relatively shallow depths, to can be used simultaneously for both electricity generation and for the coastal protection using the oscillating motion of the water particles. The single element constituting the system is realized by a fixed base and three movable panels that can fluctuate in a fixed angle. The waves interact with the panels generating an alternative motion which can be exploited to produce electricity. At the same time, the constraint movement imposed for the rotation of the panels is a barrier to the wave propagation phenomena, triggering the breaking in the downstream part of the device. So the wave energy will be dissipated obtaining a positive effect for the coastal protection. Currently, the efficiency and effectiveness of the system (WECPOS single module) has been studied by using numerical models. Using the FLOW-3D® software it has been possible to evaluate the hydrodynamic interactions that occur between a regular wave, with different height and period characteristics. The RANS equations, coupled with the RNG turbulence model, have been integrated on a three-dimensional channel (90.0 x 6.0 x 8.0 m), using a numerical domain made of two mesh blocks: a general one containing the entire domain (cells size 0.30 cm) and the localized one on the device (cells size 0.10 cm). With the results, by assessing the rotational angle, angular velocity, hydraulic torque of the individual panel it has been possible to estimate the potential energy production. A Matlab/Simulink model has been built to estimate the production of electric energy by means of an oleodynamic system consisting of a piston and a turbine coupled with an electric generator. About the coastal protection, by estimating some characteristic parameters of the wave motion (zero-moment wave height Hmo, transmission coefficient Kt and the average free surface elevation), the behaviour of the WECPOS device has been analyzed for its ability in wave energy dissipation.

ABSTRACT A network of European organisations with interests in the utilisation of long sea outfalls as an integral element in the sewerage of coastal communities has recently been established. The central aim is to provide a focus both for the adoption of best practices and the identification of outstanding problem areas across the European community, against the background of the standards of practice demanded by the recent implementation of the European Commission's (EC) Urban Waste Water Treatment Directive. This article is intended both to inform a wider audience of the existence of the network and to extend the call for membership both to European parties and others interested in being informed on European developments in this area.

Italian legislation provides for hazardcontingency plans to be prepared by the regional,provincial and local authorities. Despite the extentof damage often caused on the Italian coasts by theaction of the sea, sea related hazards have so farbeen usually ignored; only recently a limited budgetin some provinces was allocated for the analysis ofrisks related to storm damage. The present paper reports on the proceduresand the techniques employed and tested within theframework of the provincial contingency plan onthe coast of the Salerno province in Italy (Figure 1). The work was mainly oriented to the evaluation ofthe potential damage that can be caused by the directaction of waves on coastal areas and on thepreparation of hazard maps. The methods and the datathat can be used to evaluate the risks are reviewed here,first by rapid examination of the wave fieldformation offshore and its transformation on shallowwater and then by considering the run-up on beachesand infrastructures; the paper is focussed inparticular on these latter problems, which – formsome point of view – are original and specific tocivil protection problems.

C.C. Giarrusso , E.Pugliese Carratelli,  G. Spulsi
Solutions to Coastal Disasters 2002 San Diego 2002

The paper  reports on the experience gained by the Authors during the compilation of Civil Protection Contingency Plans for Italian Local and Watershed Authorities, as well as on the related research activities.
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The main task carried out in connection with such work was the drawing up of hazard maps for different time horizons (e.g. 3 and 10 years) and different damage levels;  the problem associated with both coastal erosion forecasting (which affects long term risks) and wave run-up (which determines short term risks and hazard levels) will be quickly reviewed with a strong emphasis on the operational application.  Thus no discussion will be provided about the relative efficiency of long-shore erosion models – about which a wealth of literature already exists – while some information will be provided about the use of laser altimetry, ortophoto imagery and conventional mapping techniques in providing data on the coastline position.

A special emphasis will be given on the techniques used to evaluate run up risk on low coasts, by comparing results given by standard formulae with those obtained by making use of 2D shallow water numerical models of waves;  details on model calibration techniques will be given and the connection between the model output and the potential damage to coastal infrastructure is discussed.

Della Rocca, M.R., Carratelli, E.P.
A model for wind speed and wave height retrieval from radar altimeter measurements
2000  European Space Agency, (Special Publication) ESA SP

Source of the Document European Space Agency, (Special Publication) ESA SP (461), pp. 735-743
A numerical algorithm is here proposed to simulate the measurement of ocean wave height and wind speed by radar
altimeter. The algorithm takes into account a realistic ocean wave spectrum and employs a parametric sub-model to
simulate the electromagnetic waves scattering from the surface, thus providing greater flexibility and realism than the
analytical models currently used. The model is shown to be consistent even when different backscatter models are
employed, and numerical results prove that the measured value of the significant wave height does not depend upon the
wave period while - on the opposite - wind speed measurements are significantly affected by it.
The aim of this work is two-fold: on the one hand to provide a tool to improve the understanding and thus the accurate
calibration of altimeter data, and on the other hand to develop a model which could eventually be used to simulate the sea
state response as seen by the altimeter and by other microwave instruments.

ABSTRACT The effectiveness of natural circulation and ventilation systems based on the “solar chimneys” principle has been tested for a number of years at numerous sites, but thermal and fluid mechanical aspects of their operation need to be fully understood before conclusive results can be supplied; a long term research work has therefore been undertaken by the authors, including both experimentation in two test sites in Italy and numerical simulation.In the present paper the heat transfer equation for one dimensional laminar flow is numerically solved with the appropriate radiative boundary conditions.Temperature fields calculated in this way are then employed to evaluate air density variations and consequently the upward driving force available to overcome head losses in the air circulation.Optical plate spacing in steady state conditions appears to be strongly dependent on head losses occurring outside the collecting section and on winter or summer use of the system; it shows a softer dependence on incident solar energy fluxes.

A 50 sq m solar linear concentrator plant with cavity boilers has been realized in a brewery to evaluate the applicability of using solar energy to supply industrial process heat in the 120-300 C range. The aims of this plant include the experimental testing of a mathematical computer model to obtain a general computer code simulating the heat and mass transfer phenomena in the plant, measuring the plant and cavity boiler photothermal conversion efficiency, and solving the problems arising from the joining of the solar plant with the preexisting brewery water-steam network. Linear parabolic concentrators which track the sun were used, having mirrors with an 0.86 reflectivity; the plant is used to overheat pressurized water before entering the traditional boilers for vaporization. Preliminary experimental results indicate that thermal losses from the Cu pipes are strongly dependent on atmospheric conditions, necessitating the soldering of the pyrex glass and the Al-Fe boiler envelope.