Artigos de Revista

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Na actual configuração do reforço de potência de Venda Nova II, a implantação da caverna da centralsitua-se no maciço granítico da Borralha a uma profundidade de 350 metros. A partir da superfícieforam executadas 4 sondagens verticais, profundas, com recuperação contínua de amostra. Entre essesfuros foram seguidamente realizados leques sísmicos para obtenção de tomografias sísmicas develocidade das ondas longitudinais em várias secções entre furos. As tomografias sísmicascontribuíram, em conjunto com a geologia de superfície e os resultados da prospecção mecânica, paraa definição do modelo geológico-geotécnico do maciço rochoso e para a localização da caverna dacentral.

An improvement on the simulation of outgoing waves on a time dependent numerical model for water wave propagation in the nearshore region is presented. The governing equations consist of a system of first order partial differential equations (PDEs), the equation of continuity and the equation of motion. A comparative study of first order radiation boundary conditions (BCs) and first order radiation BCs combined with sponge layers is presented for cases where outgoing waves leave the numerical domain of calculation through the open boundary. A reduction of spurious reflections from the numerical open boundaries can be obtained with an irrelevant increase in terms of computational cost.

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This paper investigates the generation of flow mass errors in finite element shallow water models and the effect of these errors in the mass conservation of Eulerian-Lagrangian transport simulations. Flow mass errors are shown to be similar for several primitive and wave equation formulations. These errors occur primarily in areas of steep bathymetric gradients and near complex boundaries. Forcing Eulerian-Lagrangian transport simulations with nonconservative flow fields generates important mass imbalances, which can be mitigated by refining the flow grid.Comparatively, refining the transport grid only reduces marginally the mass errors.

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A two-dimensional simulation of wave propagation is used to investigate wave transformation over the complex bottom geometry of the Tagus estuary entrance. The application of a hyperbolic numerical model based on the mild-slope equation in such large coastal area, where wave transformation is due to the simultaneous occurrence of the processes of refraction, diffraction, reflection and breaking, is done for the first time.Wave climate analysis is obtained for a vital area, the access to the port of Lisbon, where there is no field data available. Like in other coastal areas worldwide, navigation routes and strong currents are an obstacle to find strategic locations for wave-rider stations. Model results reveal the sheltering effects of the existent submerged sand bars in the estuary entrance against small frequency wave energy entering through the navigation channel. High frequency incoming waves are less susceptible to dissipate energy through the process of wave breaking over the bars, thus causing higher disturbance into the channel.

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