Publications

O Porto de Leixões, localizado na costa norte de Portugal, é um dos maiores do país, recebendo diariamentevários navios de grandes dimensões. Um dos principais postos de acostagem situa-se à entrada do porto e encontra-se sujeito à agitação marítima que é difratada pelo olhe principal de proteção do porto. Para avaliar dos movimentos induzidos no navio estacionado nesse posto de acostagem e as forças exercidas nas suas amarras e defensas pela agitação incidente, utilizou-se o modelo físico de Leixões, construído num dos tanques do LNEC. Neste modelo físico, encontra-se representada a envolvente do porto de Leixões, assim como a sua batimetria. O modelo do navio

An alternative to the energy matrix expansion, due to the increase of global electricity demand, is the renewable sea wave energy source, which has high energy potential. The Oscillating Water Column (OWC) converter is one of the most studied, although it is not yet used at commercial scale. Therefore, searching the optimal geometric configuration is fundamental to turn this device viable. This study proposes a numerical analysis of an onshore OWC for different slopes of chamber walls (from 40o to 90o) and equipped with a Wells turbine. Simulations of incompressible 2D flows are performed by means of the FLUENT® software, which is based on Reynolds-averaged Navier-Stokes (RANS) equations. The k-

The most studied device used for extracting wave energy is the Oscillating Water Column (OWC). In general, numerical simulations of these cases by means of models based on Reynolds Averaged Navier-Stokes equations adopt the Volume of Fluid method to deal with the free surface flow which is considered incompressible in both water and air. The aim of this study is to investigate the influence of the compressibility effect on the air inside the OWC chamber by the FLUENT® numerical model. A methodology is implemented, taking into account both water and air flows incompressible, but, at every instant, a pressure condition is imposed on the top boundary of the chamber to consider the compressibility effect. This pressure condition is based on an analytical equation that considers the isentropic transformation of the air and effects of Wells and impulse turbines. Results of compressible and incompressible numerical models are compared. The amplification factor, the root mean square of air pressure inside the chamber and OWC efficiency in relation to incident wave period, wave height and turbine characteristic relation are analyzed. Results show that air compressibility effects can diminish the predicted OWC efficiency up to about 20% in both Wells and impulse turbines.

In this study, a numerical analysis of the performance of two Oscillating Water Column (OWC) wave energy converters, at different front and back wall slopes, was carried out. The first device had vertical front and back walls and the second one had its wall slopes of 40° in relation to the horizontal plane. The FLUENT® numerical model, which is based on the Reynolds-Averaged Navier-Stokes (RANS) equations, was used. The Volume of Fluid (VoF) method was employed to take into account free surface flows. The case study comprised a 10 m deep flume with an onshore OWC at its end, equipped with a Wells turbine. A 2D hydrodynamic mathematical model was employed and a 3D air pressure effect inside the OWC air-chamber was considered. Analyses of the hydrodynamics behavior, fluid-structure interaction outside (run-up/down, reflected waves) and inside the chamber (free surface elevation, sloshing) and energy distribution (pneumatic extracted energy, reflected wave energy and energy losses) were conducted. Results showed that the device with inclined walls had the best efficiency in comparison with the other one. However, the latter showed lower variation in efficiency in the wave period range than the former.

The main objective of this study is to investigate differences of random incident waves from regular ones in performance of wave energy converters (WEC). A numerical analysis of an onshore oscillating water column (OWC) WEC is carried out by means of the FLUENT® software, which is based on Reynolds - Averaged Navier-Stokes equations. Analyses of the efficiency of an onshore OWC device with similar characteristics of the Pico

Atualmente, mais importante que assegurar a resistência de um aglomerado urbano a um eventual invasor, importa garantir a sobrevivência a catástrofes naturais das infraestruturas críticas que garantem a salubridade das condições de vida nesse aglomerado, a mobilidade dos habitantes e o abastecimento de bens essenciais. Em rigor, face ao carater aleatório destas solicitações, pretende-se que, uma vez terminadas essas solicitações extremas, eventuais estragos causados pelas mesmas não impeçam o restabelecimento, em tempo útil, das atividades normais da população. Nesta comunicação apresentam-se ferramentas e procedimentos para avaliação do risco associado a infraestruturas críticas com um viés para o controlo de cheias urbanas e de infraestruturas de transporte marítimo.

The current program of Systematic Observation of Maritime Works (OSOM+), under development at the National Laboratory for Civil Engineering (LNEC), is essentially applied to rubble mound breakwaters. The OSOM

HIDRALERTA is a forecast and early warning system for coastal and port regions capable of predicting emergency situations, as well as carrying out risk assessment. The system concentrates on evaluating wave overtopping and flooding scenarios. It uses offshore sea-wave and wind forecast data, as well as tide data, as input to determine wave overtopping at specific locations. The calculation of the mean overtopping discharge over a structure is made through artificial neural network (ANN) tools and/or empirical formulae, which are able to define the spatial distribution of the flow behind the structure.The HIDRALERTA system is composed of four modules developed in Open Source Web Technology, mainly using the Python Language. The Warning System can be configured and adapted for specific scenarios. The system has been successfully tested for the Port and Bay of Praia da Vitória, Terceira Island, Azores, Portugal, and is now under development and being implemented at the ports of Madalena do Pico and S. Roque do Pico.This paper describes the work carried out to date on the system and its application to these two ports in the Pico Island, Azores.

A set of scale-model tests carried out to enlarge the range of wave steepness values analysed in run-up, overtopping and armour layer stability studies, focusing on oblique extreme wave conditions and on their effects on a gentler slope breakwater

Mechanical constraints have a non-negligible influence in the motion of oscillating wave surge converter (OWSC) devices. The key novelty of this paper is a numerical simulation tool for OWSCs that does not neglect or significantly compromise mechanical constraints such as hydraulic power take-off (PTO) system, revolute joints and frictional contacts among components. The paper is aimed at presenting the key components of the numerical simulation tool and at validating it with laboratory data featuring an OWSC with mechanical constraints under regular and irregular waves. It is based on the implementation of the multibody solver of Project Chrono under the Smoothed Particle Hydrodynamics (SPH) model of DualSPHysics, where the SPH solver resolves the interaction between wave and flap and the multibody solver resolves the interaction between flap and mechanical constraints. Comparison between numerical results and experimental data show that the numerical simulation tool properly predicts the dynamics of the OWSC. Furthermore, in what concerns hydrodynamics of the near-flap flow, the computed and measured free-surface elevations and phase-averaged flow field show reasonable agreement. Once properly validated, the numerical simulation tool is then applied to study the influence of several mechanical constraints, PTO damping characteristics and flap inertia on the hydrodynamic of the OWSC. The viability of OWSC design solutions based on the developed numerical simulation tool is emphasised, in view of its performance in the test cases to which it was subjected.

Encontra-se em curso a empreitada da 3.ª Fase de ampliação do Molhe Leste do Porto de Sines em 750 m, a qual irá conferir a esta estrutura um comprimento total de 2250 m. Esta empreitada tem por intuito permitir alargar a bacia portuária abrigada que se encontra dedicada ao Terminal de Contentores de Sines (Terminal XXI), de molde a permitir (i) garantir condições adequadas de abrigo à agitação marítima dos novos postos de acostagem do Terminal ainda não construídos, (ii) proporcionar melhores condições de manobras de acesso e rotação dos navios de maiores dimensões, (iii) incrementar a operacionalidade do posto já existente, cujas taxas de utilização têm vindo a crescer, e (iv) não condicionar a expansão do porto para sul.

Wave-induced flooding represents a threat and sea-level risk will exacerbate the problem.

Disaster risk reduction are crucial to minimize the loss of lives and livelihoods, and to enhance community resilience and preparedness to extreme climate-related events.

Neste trabalho, utilizou-se o modelo numérico SWASH para avaliar os volumes galgados em ondas individuais no quebra-mar da Ericeira. Começa-se por definir o valor do coeficiente de Manning a utilizar no talude do quebra-mar, para simular perda de energia provocada pela rugosidade e pela percolação no processo do galgamento, comparando o volume galgado previsto pelo modelo numérico com os valores medidos nos ensaios com modelo físico realizados no LNEC, para um dado estado de agitação. Depois, para ondas selecionadas do mesmo estado de agitação verifica-se se o modelo numérico fornece valores semelhantes aos do mesmo modelo físico.

This paper presents a safety system for maneuvering and moored ships at the Port of Sines developed in the scope of the BlueSafePort project. The system is described in terms of its development and architecture, the functioning of its numerical models, the data flow and processing and the risk assessment used to issue alerts. The web platform and the mobile application where the relevant results to assess the referred risks are disseminated are also presented. The system provides 3-day advance forecasts of sea agitation, wind and tide conditions, as well as ship motions, identifying situations that could have serious consequences for ships maneuvering or moored inside the port. The system issues alerts associated with risk levels based on safety and operability criteria for ships' motions and forces in their mooring systems.

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Neste trabalho são apresentados os resultados da comparação entre três metodologias para obtenção de modelos tridimensionais de superfície, aplicadas à situação específica do modelo físico 3D do prolongamento do molhe leste do porto de Sines: são elas as aqui designadas técnicas

Due to its extensive coastal zone, Portugal owns many related maritime structures, the most common of whichare breakwaters that usually protect man-made harbours.These maritime structures, especially rubble-mound breakwaters, are assumed to be at risk in the design proccess, due to the load they can withstand. Therefore, at some point in the life of the marine structure, repairs willbe required, and monitoring programs are deemed of paramount importance in assessing damage evolution ofsuch structures.The use of an UAV (Unmanned Aerial Vehicle), or drone, has enriched ongoing LNEC

Entre 2016 e 2020 foram realizados os Estudos e Projetos e Estudos de Impacto Ambiental (EIA) dos projetos do Prolongamento do Quebra-mar Exterior e das Acessibilidades Marítimas do Porto de Leixões, os quais envolveram ensaios em modelo físico reduzido realizados no Laboratório Nacional de Engenharia Civil (LNEC) entre outubro 2016 e abril 2017, encontrando-se atualmente em curso a respetiva empreitada de construção. Os estudos, projetos e ensaios bi e tridimensionais em modelo reduzido do Prolongamento do Quebra-mar Exterior em cerca de 300 m, destacam-se essencialmente por se tratar de um quebra-mar sujeito a um regime de agitação consideravelmente severo e por envolver o uso de blocos de betão de alta densidade (peso especifico de 27,2 kN/m3 a 32 kN/m3 ) do tipo Antifer, cujo comportamento idráulico e estrutural, apesar da experiência adquirida na utilização deste tipo de blocos no Molhe Sul da Barra do Rio Douro (também com betão com peso especifico de 32 kN/m3) e no Molhe Leste de Sines (peso especifico de 25,4 kN/m3 a 30,8 kN/m3), ainda se reveste de alguma complexidade. No âmbito destes estudos realizou-se inicialmente o Estudo Prévio (EP), com base no qual se realizaram os ensaios bi e tridimensionais, e em simultâneo com estes últimos, realizou-se o Projeto de Execução (PE). Neste, e com o objetivo de aumentar a segurança da estrutura, adotaram-se generalizadamente blocos de maior peso do que os ensaiados. Pretende-se com esta comunicação destacar as particularidades da adoção de blocos

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