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- Desenvolvimentos iniciais do projeto To-SEAlert: galgamento e inundação em zonas portuárias e costeirasPublication . Fortes, Conceição; Reis, Maria Teresa; Santos, João Alfredo; Poseiro, Pedro; CAPITÃO, RUI; Pinheiro, Liliana; Lemos, Rute; Fonseca, Ana; Barateiro, José; Serrazina, Vera; Craveiro, João; Ferreira, José Carlos; Duarte, Cláudio Macedo; Andriolo, Umberto; Taborda, Rui; Silva, Ana; Lara, JavierO desenvolvimento de capacidade para prever a agitação marítima ao nível das bacias oceânicas com alguns dias de antecedência estimulou o aparecimento de sistemas informáticos para previsão dos efeitos da agitação marítima em zonas costeiras e portuárias. O HIDRALERTA é um desses sistemas: partindo das características da agitação marítima ao largo e utilizando modelos numéricos para a propagação da agitação marítima estima os parâmetros relevantes da agitação marítima para a avaliação do galgamento e do espraiamento quer em zonas portuárias, quer em zonas costeiras. O projeto de investigação e desenvolvimento To-SEAlert financiado pela Fundação para a Ciência e a Tecnologia e envolvendo o LNEC, a FCiências.ID, a NOVA.ID.FCT e o ISEL pretende melhorar as funcionalidades daquele sistema no que se refere às metodologias de previsão do galgamento e da delimitação da zona inundada, bem como no apoio à resposta a situações de emergência envolvendo aquele fenómeno. Esta comunicação pretende descrever o racional que justifica a existência do projeto, as tarefas em que o mesmo foi dividido e os principais resultados esperados.
- Energy assessment of potential locations for OWC instalation at the Portuguese coastPublication . Anastas, Gael; Santos, João Alfredo; Fortes, C. J. E. M.; Pinheiro, LilianaThis work aims to determine the exploitable wave energy resource at five potential sites close to harbour pro-tection facilities at the Portuguese coast, namely at the Azores archipelago, at Madeira Island and at Sines, on the coast of mainland Portugal. For that purpose, a third-generation wave model SWAN is used to transfer the offshore estimates of sea wave conditions to those points over the last 40 years. Sea states and wind fields are provided by the climate reanalysis datasets ERA5. Using sea states as boundary conditions and wind fields as forcings in the numerical domains of the SWAN model, the sea states were propagated shoreward, in order to estimate and analyse the wave 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 analysed since it is of paramount importance for the efficiency of Wave Energy Converters (WEC). This assessment showed that the best location for the installation of dual-chamber OWC devices is at the Azores archipelago.
- Risk analysis and management of moored ships in portsPublication . Pinheiro, Liliana; Fortes, Conceição J. E. M.; Santos, João AlfredoThe risks associated with mooring of ships are a major concern for port and maritime authorities. Sea waves and extreme weather conditions can lead to excessive movements of vessels and mooring loads affecting the safety of ships, cargo, passengers, crew or port infrastructures. Normally, port activities such as ships' approach manoeuvres and loading/unloading operations, are conditioned or suspended based solely on weather or wave forecasts, causing large economic losses. Nevertheless, it has been shown that some of the most hazardous events with moored ships happen on days with mild sea and wind conditions, being the culprit long waves and resonance phenomena. Bad weather conditions can be managed with an appropriate or reinforced mooring arrangement. A correct risk assessment must be based on the movements of the ship and on the mooring loads, taking into account all the moored ship's system. In this paper, the development of a forecast and warning system based on the assessment of risks associated with moored ships in port areas, SWAMS ALERT, is detailed. This modular system can be scaled and adapted to any port, providing decision-makers with accurate and complete information on the behaviour of moored ships, movements and mooring loads, allowing a better planning and integrated management of port areas.
- Physical modelling of motions and forces on a moored ship at the Leixões portPublication . Santos, João Alfredo; Pinheiro, Liliana; Abdelwahab, Hossam S.; Fortes, Conceição; Pedro, Francisco G. L.; Capitão, Rui P.; Hinostroza, Miguel; Soares, Carlos GuedesThis paper describes the physical model, experimental setup and tests performed at the Portuguese Civil Engineering Laboratory (LNEC), to study the motions and forces of a moored ship at the Leixões port, for different sea states in irregular waves. The tests were carried out at one of the wave tanks of LNEC, where the Leixões port layout was implemented at scale 1:80 with the detailed model similar to the prototype bathymetry and surrounding structures. The moored ship is a 3.43 m long scale model of the well-known “Esso Osaka” tanker and is moored to the pier A of the oil terminal at 0.135 m draft. Several types of measurements were recorded in this study. The freesurface elevation and wave direction were measured with a set of resistive wave gauges. The wave velocities at the entrance of the harbour were measured with an acoustic Doppler velocimeter. Motions of the moored ship were measured with the OptiTrack™ motion capture system whereas forces on fenders and mooring lines were measured with load cells attached to a complex spring system developed at LNEC. Several tests were carried out for a number of incident sea states characterized by a JONSWAP spectrum, with different significant wave heights and peak periods. The measurement, analysis and results obtained for the incident wave conditions characterized by a significant wave height of 6 m and a peak wave period of 14 s are presented and discussed in this paper.
- Modelação física e numérica da interação hidrodinâmica entre dois naviosPublication . Pedro, Francisco; Pinheiro, Liliana; Santos, João Alfredo; Fortes, Conceição J.E.M.; Hinostroza, MiguelNesta comunicação, analisa-se, recorrendo à modelação física e à modelação numérica, a interação hidrodinâmica entre dois navios, um dos quais parado, o navio “Esso Osaka”, e o outro em movimento, o navio “Aurora”. Os movimentos do navio parado são induzidos pela onda de esteira causada pelo outro navio que navega nas imediações daquele. Foram realizados testes para várias velocidades do navio em movimento, o Aurora, e para diferentes níveis de água. Efetua-se uma análise dos resultados obtidos para as diferentes condições de teste, quer da agitação gerada, quer dos movimentos induzidos no “Esso Osaka”. Relativamente à agitação gerada, as ondas de esteira, comparam-se os valores medidos com fórmulas empíricas da literatura. Finalmente, os movimentos registados são analisados e comparados, para algumas condições de teste, com os obtidos numericamente, recorrendo ao pacote numérico para simulação do comportamento de navios amarrados, SWAMS. Avalia-se o desempenho deste pacote numérico.
- Numerical and experimental studies on ship motions induced by passing shipPublication . Pedro, Francisco G.; Santos, João Alfredo; Pinheiro, Liliana; Fortes, Conceição J.; Hinostroza, MiguelTo investigate the ability of numerical models to simulate the behavior of moored ships subjected by ship-wake waves, use is made of scale model tests where a ship model sails with constant speed along a straight path at a constant distance from an otherwise motionless ship. The tests were carried out at one of the wave tanks of the Portuguese Civil Engineering Laboratory (LNEC). The moving ship is a self-propelled scale model of the "Aurora" chemical ship whereas the otherwise motionless ship is a scale model of the "Esso Osaka" tanker. The free-surface elevation was measured with a set of resistive wave gauges and ADVs. The tanker's movements, induced by the wake waves, were measured along the six degrees of freedom with a gyroscope deployed inside the ship. The numerical model WAMIT provides, in the frequency domain, the quantities required to estimate the hydrodynamic forces associated to the interaction of a free-floating ship with waves. The BAS model uses those hydrodynamic forces to study in the time domain the ship interaction with any sea-waves acting on it. Wind and current actions can also be accounted for. The results of these numerical models are compared to the measurements made in the several repeats of one of those scale model tests, in terms of the response amplitude to several wave components. These comparisons enabled the evaluation and validation of the numerical models parameters' calibration process.
- Characterization of ship motions induced by wake wavesPublication . Pedro, F. G. L.; Pinheiro, Liliana; Fortes, Conceição; Santos, João Alfredo; Hinostroza, M. A.This paper analyses the hydrodynamic interaction between two ships, one stationary and the other navigating nearby, using physical and numerical modelling. The passing ship is a self-propelled scale model of the "Aurora" chemical tanker whereas the stationary ship is a scale model of the "Esso Osaka" oil tanker. The tests were carried out for several values of the "Aurora" advance velocity and for different water levels. The data obtained for the different test conditions was analyzed in what concerns both the characterization of the generated wake waves and induced movements of the "Esso Osaka". These motions were compared with results from the numerical package SWAMS, which simulates the movements of a ship (moored or free-floating) under different wave, wind, and current actions. The time series of the "Aurora" wake waves were used to define the incident waves in the SWAMS package. An analysis on the water depth influence on the ship movements is made, for both numerical and physical results.
- Projeto To-SEAlert. Desenvolvimentos recentesPublication . Zózimo, Ana Catarina; Fortes, Conceição; Santos, João Alfredo; Pinheiro, Liliana; Lemos, Rute; CAPITÃO, RUI; Fonseca, Ana; Roque, D.; Taborda, Rui; Silva, Ana; Serrazina, Vera; Craveiro; Reis, Maria Teresa; Andriolo, Umberto; Ferreira, José Carlos; Jóia Santos, C.O projeto To-SEAlert tem como objetivo a inclusão de um conjunto de ferramentas/metodologias de modo a tornar o sistema HIDRALERTA (Poseiro, 2019, Fortes et al., 2020, Pinheiro et al., 2020) mais eficiente, fiável e robusto. Essas ferramentas incluem o uso de imagens de satélite e de vídeo, de modelação numérica e física, métodos quantitativos e probabilísticos para a avaliação do risco e planeamento de emergência, para melhorar a eficiência e a confiança no sistema, bem como proporcionar a sua validação. Este projeto tem como objetivo principal a implementação de um sistema que seja capaz de apoiar as autoridades responsáveis na monitorização, prevenção e gestão de situações de emergência. Este artigo apresenta o trabalho desenvolvido recentemente nas diferentes tarefas do projeto, entre o qual se pode destacar o desenvolvimento do protótipo do sistema para a zona costeira da Costa da Caparica, a validação do protótipo do porto da Ericeira com recurso a imagens de vídeo-monitorização, o teste de modelos numéricos para o cálculo do galgamento, e a implementação de metodologias de avaliação quantitativa das consequências do risco.