2D Model of a Floating Body Under Nonlinear Waves

A model describing the dynamics of a floating body by solving the NS-equations in a moving grid framework with free surface is presented. The model has several interesting features, like the peculiar way of describing: a) the grid movements; b) the slip boundary conditions in presence of a wet and dry interface; c) the generation of waves and, to some extents, the sponge layers. The investigated feature is the ratio between the oscillation of the floating body and the wave oscillation, which is usually quite overestimated by viscousless models when the load frequency is close to the floating body eigenfrequency. A simulation of this condition with the non-linear model reproduced much more closely the experimental results described in Ruol and Martinelli (Comsol User Conference, 2007) than the corresponding simulation carried out with a classical model based on linear waves and irrotational flow

Sulla disposizione ottimale di frangiflutti galleggianti a catamarano combinati a convertitori di energia ondosa

- La ricerca in cui \ue8 inserito questo lavoro mira allo sviluppo di un dispositivo ibrido costituito da un convertitore di energia ondosa accoppiato ad un frangiflutti galleggiante. - Il frangiflutti, ancorato con pali, \ue8 costituito da elementi prefabbricati collegati rigidamente, in modo da formare una struttura a catamarano. - La configurazione migliore \ue8 la pi\uf9 stretta tra le due esaminate (8 m e 12 m di larghezza), che risulta molto efficiente pur senza essere soggetta a grosse sollecitazioni. - La struttura a catamarano \ue8 da preferire rispetto a quella tradizionale, a parit\ue0 di massa, sia in termini di trasmissione che di riflessione. - Il convertitore esaminato, idoneo ad integrare frangiflutti singoli, non \ue8 adatto ad integrare le strutture a catamarano

Formula to Predict Transmission for pi-Type Floating Breakwaters

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UNA METODOLOGIA PER LA VALUTAZIONE DI CRITICITÀ E PRIORITÀ DI INTERVENTO: IL CASO DEL LITORALE VENETO

open3nobilancio sedimentario, litorale Veneto, erosione, allagamento costiero, gestione integrata della zona costiera.openRuol, Piero; Martinelli, Luca; Favaretto, ChiaraRuol, Piero; Martinelli, Luca; Favaretto, Chiar

Coastal Flooding Hazard Due to Overflow Using a Level II Method: Application to the Venetian Littoral

In recent years, marine flooding and its impacts have become a question of growing interest, since coastal areas are the most heavily populated and developed land zones in the world. This paper presents a rapid tool for mapping at regional scale the hazard associated with coastal flooding due to overflow. The tool merges a recently developed numerical model that solves a simplified form of the Shallow-Water Equations and is suited for Graphic Processing Unit (GPU) acceleration, with a Level II reliability method that allows producing hazard maps of inland flooding propagation. The procedure was applied to two stretches of the Venetian littoral, i.e., Valle Vecchia and Caorle, located in the northern Adriatic Sea. The application includes the site descriptions and the resulting hazard maps that show the probability of failure in each point of the coast for a given inland inundation level

Hydraulic Experiments on a Small-Scale Wave Energy Converter with an Unconventional Dummy Pto

This paper investigates on a Wave Energy Converter (WEC) named Energy & Protection, 4th generation (EP4). The WEC couples the energy harvesting function with the purpose of protecting the coast from erosion. It is formed by a flap rolling with a single degree of freedom around a lower hinge. Small-scale tests were carried out in the wave flume of the maritime group of Padua University, aiming at the evaluation of the device efficiency. The test peculiarity is represented by the system used to simulate the Power Take Off (PTO). Such dummy PTO permits a free rotation of two degrees before engaging the shaft, allowing the flap to gain some inertia, and then applying a constant resistive moment. The EP4 was observed to reach a 35% efficiency, under short regular waves. The effects, in terms of coastal protection, are small but not negligible, at least for the shortest waves

An Iterative Refining Approach to Design the Control of Wave Energy Converters with Numerical Modeling and Scaled HIL Testing

The aim of this work is to show that a significant increase of the e_ciency of aWave Energy Converter (WEC) can be achieved already at an early design stage, through the choice of a turbine and control regulation, by means of an accurate Wave-to-Wire (W2W) modeling that couples the hydrodynamic response calibrated in a wave flume to a Hardware-In-the-Loop (HIL) test bench with sizes and rates not matching those of the system under development. Information on this procedure is relevant to save time, because the acquisition, the installation, and the setup of a test rig are not quick and easy. Moreover, power electronics and electric machines to emulate turbines and electric generators matching the real systems are not low-cost equipment. The use of HIL is important in the development of WECs also because it allows the carrying out of tests in a controlled environment, and this is again time- and money-saving if compared to tests done on a real system installed at the sea. Furthermore, W2W modeling can be applied to several Power Take-O_ (PTO) configurations to experiment di_erent control strategies. The method here proposed, concerning a specific HIL for testing power electronics and control laws for a specific WECs, may have a more general validity.This work was supported by MARINET, a European Community—Research Infrastructure Action under the FP7 “Capacities” Specific Programme, grant agreement n. 262552

Forze impulsive e sormonti su muri ricurvi soggetti ad onde non frangenti

Opere a parete verticale di tipo ricurvo per la riduzione delle portate di tracimazione. Azioni impulsive generate da onde non frangenti su pareti ricurve. Nuovo fenomeno fisico identificato e denominato "crest-confined impact"

Studio sperimentale in prototipo sulle sollecitazioni indotte dal moto ondoso in un'opera di difesa a scarpata

Nell'articolo sono esposti i risultati di uno studio sperimentale effettuato in prototipo con lo scopo di determinare il comportamento di una particlare opera di difesa a gettata investita dal moto ondosoo e dunque di determinare la trasmissione delle pressioni nel corpo della struttura. Per tale scopo sono state strumentate alcune sezioni del "Murazzo" di Caroman, nell'estremo Sud del cordone litoraneo della Laguna veneziana. Sono descritte le modalita' di installazione della strumentazione e discussi criticamente i risultati delle prove effettuate durante alcune mareggiate. I risultati delle prove appaiono di estremo interesse, anche per calibrare modelli matematici di filtrazione in regime transitorio

Vulnerability Analysis of the Venetian Littoral and Adopted Mitigation Strategy

This paper discusses the key aspects of the recent Coastal Plan of the Veneto Region (IT). Its aim is to propose a single mitigation strategy for coastal erosion that is valid for the whole Veneto Region, and possibly elsewhere, as well as a method to assign a priority level to any action. The suggested mitigation action against erosion depends on urbanization level, beach width, as well as cross-shore and long-shore sediment transport. The criterion used to give a priority level to mitigation actions is based on a vulnerability index that takes into account erosive tendency, existing coastal flooding hazards, coast value, environmental relevance, tourist pressure, urbanization level, the presence of production activities, and cultural heritage. A sample case featuring the littoral of Rosolina is also provided and includes a site description, the sediment budget, critical issues and possible mitigation measures