Publicações

Nowadays, the use of RANS-based models for simulating numerical wave flumes and studying coastal engineering structures is common and allows investigating accurately phenomena that occur in current/wavestructure interactions. Comprehension of energy transformations in these processes can support designers tooptimize the system. In this study, a methodology to evaluate the terms of the energy rate balance in coastalengineering problems is developed. The methodology is applied to the propagation of regular waves in numericalwave flumes, onshore oscillating water column wave energy converter integrated into a vertical breakwater, andtwo types of rubble-mound breakwaters. The direct determination of the energy rate due to viscous and urbulencelosses and the porous resistance in rubble-mound breakwaters are carried out by time integration insidethe computational domain. Besides, the reflected and transmitted energy rates in the flume are calculated bymeans of this methodology, instead of the standard gauge methods, commonly used in physical and numericalflumes. Complementary, studies may be carried out for random incident waves and the methodology can beapplied to 3D wave tanks.

The evaluation of damage progression caused by wave action on physical models of rubble-mound breakwaters can be accomplished through two types of methods: quantifying the movements and falls of the resistant armor elements by visual inspection (the traditional, classical method) or determining the eroded volumes and depths between consecutive surveys of armor layers using sensors and photogrammetric methods (3D scanning methods). Of the latter, one may use techniques such as the so-called "Kinect", "Photogrammetry" and "LiDAR". The end-product of these techniques is, among others, point clouds, which allow obtaining three-dimensional surface models. In this paper, four of the latter techniques (3D scanning methods) are briefly described, and a comparison is made between them regarding their usability in current tests, their advantages and disadvantages, among themselves for a study case of the physical 3D model of the Ericeira breakwater. In evaluating survey quality across the four methods, RMSE (root mean square error) was employed to align obtained point clouds with ground control points (GCP). Notably, Photogrammetry, Kinect, and Azure techniques showed excellent RMSE values. Conversely, the LiDAR-derived-method cloud, using a smartphone with LiDAR sensor and 3dScanner app, fails to yield acceptable and accurate results for the research objectives of this paper.

Data of wave dissipation over vegetation fields was collected from laboratory flume experiments, fordifferent vegetation and wave conditions. An analytical model and a numerical model are applied to estimatethe wave dissipation obtained in the experiments, through the calibration of the bulk drag coefficient (CD).Results and conclusions will analyse and compare each model behaviour and obtained CD values.

Downtime of port terminals results in large economic losses and has a major impact on the overallcompetitiveness of ports. EarlyWarning Systems (EWS) are an effective tool to reduce ports

Coastal hazards such as flooding and erosion can cause large economic and human losses. Under this threat, early warning systems can be very cost-effective solutions for disaster preparation. The goal of this study was todevelop, test, and implement an operational coastal erosion early warning system supported by a particularmethod of machine learning. Thus, the system combines Bayesian Networks, and state-of-the-art numericalmodels, such as XBeach and SWAN, to predict storm erosion impacts in urbanized areas. This system wasdeveloped in two phases. In the development phase, all information required to apply the machine learningmethod was generated including the definition of hundreds of oceanic synthetic storms, modeling of the erosioncaused by these storms, and characterization of the impact levels according to a newly defined eerosion iimpactindex. This adimensional index relates the distance from the edge of the dune/beach scarp to buildings and theheight of that scarp. Finally, a Bayesian Network that acted as a surrogate of the previously generated informationwas built. After the training of the network, the conditional probability tables were created. These tablesconstituted the ground knowledge to make the predictions in the second phase. This methodology was validated(1) by comparing 6-h predictions obtained with the Bayesian Network and with process-based models, the latestconsidered as the benchmark, and (2) by assessing the predictive skills of the Bayesian Network through theunbiased iterative k-fold cross-validation procedure. Regarding the first comparison, the analysis considered theentire duration of three large storms whose return periods were 10, 16, and 25 years, and it was observed that theBayesian Network correctly predicted between 64% and 72% of the impacts during the course of the storms,depending on the area analyzed. Importantly, this method was also able to identify when the hazardous conditionsdisappeared after predicting potential consequences. Regarding the Regarding the second validationapproach, second validation approach, the k-fold cross-validation procedure was applied to the peak of a set ofvarying storms and it demonstrated that the predictive skills were maximized (63%

This paper investigates the influence of sea severity and mooring line pretension configuration on the operabilityof a moored vessel at a modified berthing site inside a port. A physical model was constructed to replicate thenew layout of the port of Leix

A wave flume is used to study a scaled model of a stepped bottom dual-chamber Oscillating Water Column (OWC) installed onshore. Compared to traditional single-chamber OWCs, the use of dual-chambers is expected to widen the range of sea states in which the OWC is more efficient, and the step, in front of the first chamber, boosts the capturing energy capacity of the device. The Power Take-Off (PTO) system is modelled as an air opening in the pneumatic chambers. Several experiments combining regular incident waves and PTO damping conditions are performed. Results of the amplitudes of the free surface elevations inside the chambers show that the device can amplify the incident wave amplitude up to 1.57 times in chamber 2. Results of the primary efficiency show that the device is highly dependent on the PTO damping characteristics and can reach around 40% for a wide range of wave periods. Results of the reflection analysis show that the reflection coefficient is also dependent on the PTO damping characteristics but remain lower than 0.6 for all the studied cases. Sloshing phenomenon (mostly in the cross-section direction) was observed for a wavelength close to the cross-section dimension, impacting negatively on the device pneumatic performance.

Laboratory experiments of wave propagation over rigid and flexible vegetation fields, with the same configurations, were conducted to understand the effect of vegetation flexibility on the drag coefficient (CD). The direct method and the least squares method (LSM), based on force and flow measurements, are applied to calculate the CD in the experimental conditions. The formulations of both methods are extended to estimate the CD for flexible vegetation cases. A video analysis was performed to account for the swaying motion. Typically, wave dissipation is lower for flexible than for rigid vegetation of the same configuration, under the same flow condition. Therefore, a proportional effect in the corresponding CD results, obtained from common CD calibration to wave dissipation without considering vegetation motion, is usually observed. However, the present results show that although the wave dissipation was 34% lower for flexible relative to rigid vegetation, the respective CD values were close. CD estimations considering vegetation motion and inertia suggest that CD of flexible vegetation was up to 13% higher relative to rigid vegetation. Accounting for inertia reduced the CD for rigid vegetation up to 7%, while raised the CD for flexible vegetation up to 13%.

Aquatic vegetation in the littoral zone plays a crucial role in attenuating wave energy andprotecting coastal communities from hazardous events. This study contributes to the developmentof numerical models aimed at designing nature-based coastal defense systems. Specifically, a novelnumerical application for simulating wave

Nesta comunicação descreve-se o projecto BRISA (Interacção entre a rebentação das ondas e otransporte de sedimentos) que tem como objectivo contribuir para a compreensão e modelaçãonumérica dos fenómenos de rebentação das ondas e do transporte de sedimentos em zonascosteiras. Para este efeito, o projecto envolve a modelação numérica e experimental e a recolhade dados de campo relativos à hidrodinâmica da rebentação das ondas e ao transporte desedimentos.Neste trabalho são descritas as várias tarefas efectuadas ao longo do projecto. Apresentam-seos ensaios experimentais em modelo físico num canal de ondas, considerando diferentesbatimetrias de fundo, e as campanhas de campo realizadas na Praia de Faro e na Praia daCornélia (Costa da Caparica). Descrevem-se novas formulações associadas à rebentação, àstensões de atrito no fundo e ao transporte sedimentar, bem como a sua implementação evalidação em modelos numéricos. Apresenta-se a aplicação de modelos numéricos na simulaçãodos casos estudados em modelo físico e das condições de agitação verificadas nas campanhasde campo, que permitem validar e analisar o seu desempenho.

Neste artigo descrevem-se alguns dos métodos de separação de ondas incidentes e reflectidasmais utilizados em canais de ondas irregulares de laboratórios de hidráulica marítima. Osmétodos de Mansard e Funke (situações de fundo horizontal e de fundo variável) e de Frigaarde Brorsen (com cálculo da separação em tempo diferido), são apresentados e implementadosmediante programação em MATLAB. Estes métodos foram aplicados a séries temporais daelevação da superfície livre provenientes de simulações numéricas e de simulações físicas, emtanque, como forma de verificação da sua exactidão teórica e da sua adequada implementaçãocomputacional. Estas verificações permitiram constatar a exactidão dos métodos, para ossinais simulados numericamente, e a sua boa adequabilidade aos modelos físicos, para ossinais obtidos em tanque.

O sistema de coluna de água oscilante (CAO) é considerado um dos tipos de dispositivo deaproveitamento da energia das ondas (DAEO) do oceano tecnicamente mais conhecido, emvirtude do grande esforço de investigação de que foi objecto nos últimos anos. Já foramconstruídas diversas instalações junto a costa, em diferentes partes do mundo. A médio prazoprevê-se a instalação de parques de DAEO-CAO ao largo.No presente trabalho são aplicados dois códigos de cálculo que resolvem as equações deNavier-Stokes-Reynolds para simular os fenómenos resultantes da interacção das ondas comum DAEO-CAO. Um dos códigos (FLUINCO) é baseado na técnica dos elementos finitos e ooutro (FLUENT) na técnica dos volumes finitos.O objectivo do trabalho consiste na aplicação destes códigos, já validados para resultadoslaboratoriais para um modelo de DAEO-CAO com e sem os efeitos dissipativos de umequipamento de extracção de energia, numa situação de águas profundas e sem interferênciadas paredes laterais do canal físico. São comparados os resultados em águas profundas comos numéricos e laboratoriais, em profundidade intermédia.

A área das praias do Mexilhoeiro e Alburrica, localizada no estuário do Tejo, Portugal, sofreu nos últimos anos alterações acentuadas da sua morfologia, com ocorrência de erosões e assoreamentos que se atribuíram à movimentação aluvionar provocada pela acção das ondas geradas pela passagem de catamarans em frente às praias. As erosões puseram em risco instalações e património existentes na proximidade das praias e os assoreamentos, associados ao crescimento das restingas onde as praias se inserem, ameaçaram fechar as bacias de maré que essas formações delimitam.Em 2007, a WW - Consultores de Hidráulica e Obras Marítimas, S.A. levou a cabo, a pedido da Administração do Porto de Lisboa, S.A. (APL), um estudo para caracterização das alterações verificadas, análise das suas causas e proposta de soluções para a resolução dos problemas.Na sequência deste estudo, a APL realizou em 2009 uma alimentação artificial, com areias provenientes de zonas adjacentes às zonas afectadas, e posteriormente a monitorização da área, mediante a realização de levantamentos periódicos de perfis transversais.Este trabalho tem como objectivo a apresentação do estudo das alterações na área das praias do Mexilhoeiro e de Alburrica, da solução para a resolução imediata dos problemas que foi implementada pela APL, bem como dos resultados da monitorização que se tem vindo a executar com vista a melhorar a interpretação dos problemas existentes

Quantificar a força (ou a pressão) devida às ondas incidentes torna-se essencial para analisaros esforços exercidos sobre uma estrutura e assim poder definir a sua estabilidade. Para tal, énecessário compreender todos os fenómenos envolvidos na interacção onda-estrutura, taiscomo a rebentação, o galgamento, etc... Estes fenómenos são fortemente não lineares, o quetorna a sua modelação numérica um dos maiores desafios em CFD (Computational FluidDynamics).No presente trabalho pretende-se aplicar o modelo numérico SPH

The analysis of wave records originated by physical simulation experiments in wave flumes or tanks may be done considering suitablewave parameters, either using spectral or time analysis methods. The first type of analysis was made available in the SAM application,Capitão (2002), an integrated software package that has been in use at LNEC for some years now. However, a time analysis method waslacking in this software package. This paper describes the implementation of this time analysis method (direct method) into the existingSAM software, and the testing procedures to verify that it performs as intended. In order to test this type of analysis and to compare itwith the spectral analysis, a number of numerical and physical tests were performed using SAM and a wave flume. A comparisonbetween time-domain and frequency-domain methods was the main result obtained with this work. The comparisons made use of theparameters wave height, mean wave period and significant wave period, obtained with both methods

Wave-structure interaction generates very complex phenomena involving nonlinear processes, like wave propagation and transformation, run-up, wave breaking, and overtopping. Additionally, complex coastal structures are constructed, with impermeable or porous structures, composed by blocs or arc crown wall structures, etc. Consequently, in practical engineering projects, there are a large number of cases for which there is no appropriated empirical formula. For those cases, physical modeling is currently employed due to the accuracy of this approach and the possibility to model large areas. However, its accurate simulation on physical models strongly depends on the model scale used and needs an understanding of model and scale effects for the correct representation of the phenomenon.For studies of interaction between waves and complex structures as coastal structures, numerical modeling presents a very attractive complement to physical modeling. However, only some numerical models allow simulating wave breaking and wave overtopping correctly. The SPH (Smoothed Particle Hydrodynamics) method is a relatively new method that computes trajectories of fluid particles which interact according to the Navier-Stokes equations. The recent advances on SPH models show that Lagrangian method is a very promising alternative approach to simulate wave-structure interaction due to its completely mesh-free technique. This paper presents an application of a free surface modeling by means of the SPHysics numerical model based on Lagrangian approach [1, 2]. SPHysics was used with success in previous studies [3], where numerical results of seawall overtopping agree well with experimental data. A typical impermeable coastal structure of the Portuguese Atlantic coast is considered in the present study and features of free surface elevation and overtopping are analyzed for two different geometric configurations, differing in the crest level. These two cases represent a range of overtopping conditions varying from small discharges, more difficult to model numerically, to a considerable amount of overtopping. The SPH model provides information about the free surface and the overtopping discharge, through maximum height and water velocity, and pressure. In the final paper, the results will be presented and discussed.

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Nesta comunicação, é efectuada uma análise comparativa entre medições in situ e resultados numéricos da aplicação do modelo não linear COULWAVE para as condições de agitação verificadas na Praia de Faro durante os dias 26 a 28 de Março de 2009. O objectivo é avaliar o desempenho do modelo na simulação da hidrodinâmica da rebentação em condições reais. Este trabalho insere-se no âmbito do projecto BRISA.

Nesta comunicação, descreve-se a análise temporal, espectral e estatística de registos deelevação da superfície livre obtidos quer em ensaios em modelo físico quer utilizando modelosnuméricos. Mais ainda, efectua-se uma análise comparativa entre resultados numéricos eexperimentais, que inclui uma análise de erros (através do cálculo de viés, erro médio quadrático,índice de concordância, etc.) avaliando assim o desempenho dos modelos numéricos em estudo.Os casos em estudo correspondem aos ensaios em canal físico da simulação da propagação deondas sobre uma rampa de declive constante que termina numa estrutura de protecção costeira, paraos quais se efectuou um conjunto significativo de medições da elevação da superfície livre em váriospontos ao longo do perfil de estudo. O outro corresponde aos testes numéricos efectuados com osmodelos numéricos BOUSSiiw e COULWAVE na simulação da propagação de ondas sobre um baixioesférico para os quais existem medições efectuadas em modelo físico. Trata-se pois de um excelentecaso para validação dos modelos numéricos.A aplicação dos modelos numéricos (introdução de dados, execução dos modelos e obtenção deresultados) e principalmente as análises de dados efectuadas quer aos registos obtidos em modelofísico quer aos obtidos com os modelos numéricos foram efectuadas com a aplicação informáticaSOPRO e, mais concretamente, com a nova funcionalidade desenvolvida neste trabalho, o móduloANALISES.

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The project LIFEGARACHICO (LIFE20 CCA/ES/001641) proposes the creation of an effective flexible adaptation framework for the coastal unicipalities of Macaronesia, making specific local interventions to increase their resilience against extreme coastal events resulting from climate change. Social surveys were applied in Praia da Vitória, Terceira, Azores, to understand the civilians perception of coastal flooding events.

The project LIFE-GARACHICO (LIFE20 CCA/ES/001641) proposes the creation of an effective flexible adaptation framework for the coastal municipalities of Macaronesia, making specific local interventions to increase their resilience against extreme coastal events resulting from climate change. Social surveys were applied in both localities in order to understand the civilians perception of coastal flooding events

Realização de ensaios em modelo físico reduzido 3D para a avaliação da estabilidade do quebra-mar destacado do Porto Inlgês, Maio, Cabo-Verde

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Adverse sea conditions can cause emergency situations associated to wave overtopping, which endanger the safety of people and goods, with negative impacts for society, the economy and the environment. Therefore, a methodology to assess the overtopping risk in port and coastal areas is essential for a proper planning and management of these areas.The Portuguese National Laboratory for Civil Engineering (LNEC) has been developing the HIDRALERTA system, an integrated decision-support tool for port and coastal management, which focus in preventing and supporting the management of emergency situations and the long-term planning of interventions in the study areas. It enables the user to calculate the risk for various port and coastal activities, starting with the characterization of sea-waves, wind field and tide levels at the study regions.HIDRALERTA was already tested at different places in Portugal: Costa da Caparica beach, in Almada, and port of Praia da Vitória, in the Azores. However, in both cases, the evaluation of wave overtopping / flooding consequences was carried out using a quite simple approach. In fact, such consequences were assessed only at a global and qualitative level, based on information provided by the responsible authorities.This paper aims at testing a quantitative methodology to evaluate overtopping consequences: the Analytic Network Process (ANP). This methodology was proposed to solve complex decision-making problems and its objective is to calculate the priorities among decision elements which will define their final weights on the consequences. The ANP approach can produce interdependencies between criteria and compute the respective weight of each criterion. Such a network model with dependence and feedback improves the priorities derived from judgements and makes prediction more accurate. So, the ANP allows comparison among clusters of elements. Furthermore, in this methodology we take into account the impacts of alternatives on the importance of criteria, by normalizing the comparison matrix. Thus, the given alternatives can influence the ranking of criteria.Application of the ANP methodology to the case study of Praia da Vitória port is presented and a consequences level map is obtained.

Apresenta-se um novo sistema de alerta para navios amarrados em portos que se encontra em desenvolvimento no Laboratório Nacional de Engenharia Civil. O sistema SWAMS_ALERTA é um sistema de previsão e alerta baseado na avaliação do risco associado ao comportamento de navios amarrados em zonas portuárias.Os riscos associados a navios amarrados decorrem de movimentos excessivos, quer no plano horizontal, quer no plano vertical. Estes movimentos podem condicionar as atividades portuárias, nomeadamente cargas e descargas, mas em casos extremos podem levar à ocorrência de situações de emergência, tais como rotura de cabos, rotura de cabeços de amarração ou até colisões com o cais. As consequências deste tipo de situações envolvem sempre grandes prejuízos materiais e por vezes humanos.O sistema SWAMS_ALERTA utiliza as medições e previsões de agitação marítima para a determinação dos seus efeitos em termos de movimentos nos seis graus de liberdade e forças nas amarras e defensas quando o navio se encontra estacionado no cais. Para tal, o sistema recorre a uma série de modelos numéricos, interligados entre si. A comparação destes valores com valores máximos admissíveis pré-estabelecidos permite a avaliação, em tempo real, de situações de emergência e a emissão de alertas dirigidos às entidades portuárias.O sistema é constituído por 4 módulos:I

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