Publications

Numerical modeling of the interaction between waves and coastal structures is a challenge due to the many nonlinearphenomena involved, such as wave propagation, wave transformation with water depth, interaction between incident andreflected waves, runup/rundown and wave overtopping. For simulating such complex free-surface flows, numerical modelsbased on Lagrangian formulation, such as Smoothed Particle Hydrodynamics (SPH), are on option. Even though validationof these numerical models is essential, comparing numerical results with experimental data is not an easy task. In thepresent paper, an SPH numerical model is validated comparing numerical results of waves interacting with a compositebreakwater with data obtained from physical model tests carried out in one of the LNEC

Groins are cross shore structures built to promote shoreline stabilization. However, the specific impact of these structures on the wave conditions and velocity field nearshore (and hence, on sediment transport) is still poorly understood. Therefore, this study wishes to extend this knowledge using a numerical model, COULWAVE, previously validated with field data. For that, a typical bar-trough profile is considered and different groin lengths and orientations are tested, under the influence of different significant incident-wave heights and sea-surface levels.The hydrodynamics factors are found to have a greater impact on the nearshore wave conditions than the groin geometry. The variation of significant incident-wave height imparts the greater changes in wave height nearshore, where the groin would be located. The typical tidal range is also important, since a 2 m change in sea surface level can cause great depth changes over bathymetric features and thus influence wave propagation. Although less important, the geometry of the groin should also be considered. The greater the length, the greater the sheltering effect expected, extending further to the lee-side of the groin. The impact will also reach a broader region. With a smaller impact verified, the best orientation of the groin is hard to unravel.

The study of ways of converting ocean wave energy into a useful one and the improvement of theexisting equipment are complex engineering problems and very important issues in today

The length of the Portuguese coast, the severity of the sea conditions and the concentration of population and economic activities on its coastal zone justify the importance of studying wave-induced risks and, in particular, flooding due to wave action. Indeed, emergency situations caused by adverse sea conditions are frequent and put in danger the safety of people and goods, with negative impacts for society, economy and natural heritage. So, assessing the risk of flooding of coastal and port areas is essential for the proper planning and management of these areas. In this framework, a methodology for the flood risk assessment in coastal and port areas is under development. The methodology is embedded into the HIDRALERTA system, a novel integrated system for port and coastal management, designed to prevent emergency situations, to support their management and to forecast incidental long-term interventions. The present paper describes the methodology, the HIDRALERTA system and a case study, the São João da Caparica beach, on the Lisbon

Para reducir la agitación en el interior del puerto de Vila do Porto, Azores, se ha proyectado una modificación del muelle interior de atraque de los ferries, con el objetivo de aminorar la reflexión y disminuir el rebase, sin que con eso se reduzca demasiado el área útil de la dársena portuaria. La solución propuesta es una plataforma de forma triangular en planta apoyada en pilares rectangulares, bajo la cual se ha colocado un talud de escollera para disminuir la reflexión. Se presentan los resultados de ensayos en modelo físico 3D y los obtenidos con dos modelos numéricos RANS en lo que se refiere a presiones en la plataforma y reducción de la reflexión (el modelo IH-2VOF y el FLUENT).

Submarine outfalls need to be evaluated as part of an integrated environmental protection system forcoastal areas. Although outfalls are tight with the diversity of economic activities along a denselypopulated coastline being effluent treatment and effluent reuse a sign of economic prosperity, precautionsmust be taken in the construction of these structures. They must be designed so as to have the leastpossible impact on the environment and at the same time be economically viable. This paper outlines theinitial phases of a risk assessment procedure for submarine outfall projects. This approach includesa cost-benefit analysis in which risks are systematically minimized or eliminated. The methods used inthis study also allow for randomness and uncertainty. The input for the analysis is a wide range ofinformation and data concerning the failure probability of outfalls and the consequences of an operationalstoppage or failure.As part of this risk assessment, target design levels of reliability, functionality, and operationality weredefined for the outfalls. These levels were based on an inventory of risks associated with suchconstruction projects, and thus afforded the possibility of identifying possible failure modes. Thisassessment procedure was then applied to four case studies in Portugal. The results obtained were thevalues concerning the useful life of the outfalls at the four sites and their joint probability of failureagainst the principal failure modes assigned to ultimate and serviceability limit states. Also defined werethe minimum operationality of these outfalls, the average number of admissible technical breakdowns,and the maximum allowed duration of a stoppage mode. It was found that these values were inconsonance with the nature of the effluent (tourist-related, industrial, or mixed) as well as its importancefor the local economy. Even more important, this risk assessment procedure was able to measure theimpact of the outfalls on human health and the environment.

Neste artigo descreve-se a ferramenta numérica SWAMS que se baseia nos modelosnuméricos DREAMS, BOUSS-WMH e MOORNAV para caracterizar a resposta dum navioamarrado no interior dum porto sujeito à acção da agitação marítima. Os dois primeirosmodelos simulam a propagação de ondas lineares e não lineares em zonas abrigadas deprofundidade variável, tendo em conta os fenómenos da refracção, difracção, reflexãoparcial, dissipação de energia devida ao atrito de fundo e rebentação das ondas. Enquantoo modelo DREAMS é um modelo linear baseado na equação de declive suave, o modelonão linear BOUSS-WMH é baseado nas equações de Boussinesq. O comportamento donavio amarrado é simulado com o pacote numérico MOORNAV que engloba um modelonumérico para resolver, no domínio da frequência, os problemas de radiação e de difraçãoda interacção de corpos flutuantes com ondas e um modelo que converte os resultadosdaqueles problemas do domínio do tempo para o domínio da frequência e que monta eresolve as equações do movimento do navio amarrado, BAS.Apresentam-se asmodificações introduzidas no modelo WAMIT para calcular as forças de difracção com basenas relações apresentadas em Haskind. Tais relações, porque utilizam o potencial develocidades obtido com o modelo DREAMS ou com o modelo BOUSS-WMH, permitemlevar em conta a refracção, difracção ou reflexão que podem ocorrer na propagação dasondas para o interior de uma bacia abrigada. Para além da descrição dos modelosnuméricos na ferramenta SWAMS, apresenta-se a forma como os resultados sãotransferidos entre eles bem como aplicações da mesma para ilustrar as suas capacidades.

The current study proposes prediction formulas both for random wave runup and mean overtopping discharge at seawalls constructedon land or in very shallow water. Although several existing formulas for runup and overtopping use the incident wave characteristicsat the toes of seawalls, this study adopts the equivalent deepwater wave characteristics and an imaginary seawall slope for easy application of theformulas, especially in relation to seawalls constructed on land. The prediction formulas for overtopping use the predicted runup values. For thewave runup prediction formulas two sets of experimental data are used; i.e., a new set of data and the data obtained in a previous study. For thewave overtopping prediction formulas, the experimental data measured in a previous study are used. Comparisons with measurements showgood performances of both new prediction methods.

This paper presents the new boundary condition implemented in the LNEC SPH numerical model based on theSPHysics model and on a standard Smoothed Particle Hydrodynamic formulation: the piston-type wave maker includesnow dynamic wave absorption and allows simulating a semi-infinite flume. Verification of the active wave makerabsorption is carried out through the simulation of the interaction between a regular incident wave and an impermeablevertical breakwater. Results show that the active wave-maker allows outgoing waves to be absorbed and reflection at thewave-maker to be avoided

Este artigo aborda a análise comparativa entre as medições de agitação marítima efectuadas na Praia da Cornélia (Costa da Caparica, Portugal), durante os dias 12 a 14 de Maio de 2010, e os resultados numéricos da aplicação do modelo não-linear do tipo Boussinesq, COULWAVE. Esta análise tem como principal objectivo a avaliação do desempenho deste modelo numérico na simulação da propagação de ondas em condições reais, pretendendo evidenciar, deste modo, as suas potencialidades e limitações.As condições de fronteira do modelo foram geradas com base em séries temporais de elevação medidas a uma profundidade aproximada de 7.6 m (relativa ao zero hidrográfico

Nowadays, renewable energy is a topic widely discussed in scientific community. Specifically wave energy attracts attention because it has a high energy potential distributed throughout the planet. Oscillating Water Column (OWC) wave energy converter is one of the most studied devices that have promising perspectives to be installed commercially. This study aims investigating the influence of chamber sizes and turbine characteristics dimensions of an OWC device located at the southern Brazilian coast is carried out. Numerical simulations for incident waves with period T = 7 s and 10 s and height H = 1.5 m, by using the FLUENT® model, based on the finite volume method (VFM) are carried out. Efficiencies for different chamber sizes and Wells turbine characteristic relations (kt) in each incident wave are determined. The highest efficiencies were obtained by a chamber with 5 x 5 m and kt = 530 Pa.s/m³ in the case of an incident wave with T = 7s (52%), and 30 x 30 m and kt = 15 Pa.s/m³ at T = 10s (65%).

Port terminals downtimes lead to large economic losses and largely affect the port

This paper describes the physical model, experimental setup and tests performed to study the motions and forces of a ship moored to the pier A at the Leixões oil terminal, following the breakwater

HIDRALERTA is a forecast, early warning and risk assessment system for port and coastal areas that uses measurements and estimates of sea-waves and water levels to evaluate overtopping/flooding events. The calculation of the mean overtopping discharge over a maritime structure is performed through artificial neural network-based tools and/or empirical formulae. The system is developed in open source software, mainly using the Python language. This paper presents the application of HIDRALERTA system to reproduce the hurricane Lorenzo conditions and impacts at Lajes das Flores port on October 2nd 2019, the most affected port in Azores. This hurricane was regarded as the strongest storm to hit Azores in 20 years. The system predicted the expected results for the hurricane wave characteristics, as well as overtopping discharge volumes. Further validation still need to be improved with the collaboration of the local authorities and the use of historical data.

Numerical models are useful tools to predict the effects of storms in coastal areas. The objective of this work was to simulate the effects of storms in São Pedro de Moel beach by using XBeach. The nearshore sea state was obtained by propagating offshore conditions using the SWAN model. The XBeach model was divided into two setups to analyse overtopping events and coastal evolution. Sensibility tests, calibration, and validation, using information from different storms, were performed for the different setups. The results from the overtopping simulation were compared against results from an empirical formula. The comparison showed lower values obtained with the empirical formula. The coastal evolution run point out to the necessity of having better field data before and after storms to improve the model setting and accuracy.

The assessment of damage evolution in scale model tests of rubble-mound breakwaters can be achieved by comparing eroded depths and volumes between consecutive surveys. This paper focuses on damage evolution of a model of a rubble-mound breakwater and on the novelty of the non-intrusive survey methodologies such as laser scanning and Time of Flight (ToF) techniques, based on point clouds, enabling the extraction of profiles and the calculation of eroded depths and eroded volumes. The final objective of this work is to evaluate the applicability of the estimation the number of displaced armour units, using a non-dimensional damage parameter based on the calculated eroded volume.The paper will also describe the experiments conducted under the RODBreak, a project sponsored by the HYDRALAB+ Transnational Access Program, in which a stretch of a rubble-mound breakwater was built at the wave-current basin of the Leibniz University Hannover (LUH) to assess the structure behavior. Four scan surveys were conducted using a Faro Focus 3D laser scan, as well as a ToF sensor. Those surveys were carried out before and after two test series, in order to evaluate the eroded volume and profile evolution.

Neste trabalho é efetuada a validação do protótipo To-SEAlert para o porto da Ericeira. Para a validação dos resultados do modelo SWAN foram utilizados os dados de duas boias situadas ao largo da Nazaré e para a validação das previsões do sistema de cálculo do grau de risco foram simuladas as depressões Elsa e Fabien (ocorridas em dezembro de 2019) e que foram responsáveis por fortes danos na cabeça do molhe do porto da Ericeira. Verificou-se uma boa concordância entre os dados das boias e os resultados do modelo SWAN, tendo no entanto o modelo reproduzido melhor a direção média e a altura significativa do que o período de pico. Relativamente aos valores de galgamento, os resultados obtidos na simulação das depressões Elsa e Fabien estiveram em concordância com os valores referidos na literatura como causadores de danos nas estruturas.

This work aims to determine the exploitable wave energy resource at six potential sites, located in the Azores, Madeira and Sines breakwater city harbours. For that purpose, the thirdgeneration wave model SWAN is used to estimate the sea-wave conditions over the last 40 years. Boundary conditions of the sea states and wind fields are provided by the climate reanalysis datasets (ERA5). Using those results as inputs to the SWAN model, the sea-states were propagated shoreward, in order to estimate and analyse the wave climate conditions in the regions of interest. By combining the average energy flux per unit-length of wave front and the probability of occurrence of each sea state, the average exploitable annual energy per unit length of wave crest can be computed. The variability of this energy flux is described, since it is of fundamental importance for the efficiency of the Wave Energy Converters (WEC).

Former investigations on wave run-up and overtopping of (impermeable and permeable) coastal structures aimed at quantifying the influence of oblique waves on mean overtopping discharge, water layer thickness and velocities by developing empirical formulas of a reduction factor for wave obliquity,

In 2017, the RODBreak experiment was conducted. The experiment aimed at characterizing wave run-up, overtopping and damage in rubble-mound breakwaters. The reason for these experiments was the huge impact that climate can have on maritime structures, particularly in rubble mound breakwaters. In fact, the forecast sea level rise associated with more frequent and severe storms will have consequences either on the increase of wave runup, wave overtopping or on damage on existent structures since they were not design for those extreme values. However, for those climate change scenarios, little is known about the actual failure probability of such structures.Within this framework, a stretch of a rubble-mound breakwater was built in a wave basin. Under extreme wave conditions, with different incident wave angles (from 40° to 90°), a total of 49 tests were performed. Each test had different testing parameters, such as significant wave height (Hs), peak period (Tp) and wave direction. Also, for each test, different types of measurements were considered. Incident sea waves were measured with 3 arrays of 6 acoustic wave probes each as well as with isolated acoustic wave probes and 5 Acoustic Doppler Velocimeters (ADV

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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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