Drenaxe

Titulación: Grao en Enxeñaría Agroforestal -- Materia: Deseño e Construción de Obras LineaisEsta unidade didáctica forma parte do primeiro módulo da programación da materia “Deseño e Construción de Obras Lineais” do segundo curso do Grao en Enxeñaría Civil, que se dedica a senta-las bases da enxeñaría de estradas. No primeiro tema do módulo (UD1) preséntanse os conceptos básicos da enxeñaría do tráfico necesarios para poder aborda-lo deseño xeométrico, a construción e a conservación dunha estrada. A continuación, no segundo tema (UD2), estúdanse os conceptos fundamentais, as bases teóricas e os aspectos normativos do deseño xeométrico ou trazado dunha estrada. Co seguinte tema (UD3) comeza a parte do módulo dedicada ao deseño e construción da infraestrutura dunha estrada. Neste caso preséntanse os aspectos máis importantes relacionados coas explanacións ou obras de terras. Na presente unidade didáctica (UD4) explícanse os fundamentos do deseño dos sistemas de drenaxe dunha infraestrutura viaria. Preséntanse, en primeiro lugar, os conceptos relativos á drenaxe superficial: estudos hidrolóxicos, estudos hidráulicos, descrición e deseño dos diferentes elementos de drenaxe, etc. e posteriormente, abórdanse brevemente os conceptos básicos relativos á drenaxe subterránea. O módulo péchase cun tema no que se estuda a problemática do deseño, construción e conservación dos firmes (UD5), que constitúen a superestrutura dunha estrada. No segundo módulo da materia estúdase o deseño, construción e conservación doutra tipoloxía de obra lineal, os ferrocarrís. Estas dúas tipoloxías, estradas e ferrocarrís, teñen moitas cousas en común, polo que unha gran cantidade dos contidos traballados no primeiro módulo serán de gran utilidade, senón directamente mediante certas adaptacións, na segunda parte da materia. Para o correcto seguimento da mesma recoméndase que os alumnos teñan coñecementos básicos de Hidroloxía e Hidráulica de canles. En todo caso os conceptos relativos a estas disciplinas atópanse explicados con bastante profundidade na propia unidade. Ademais de aos alumnos de 2º curso do Grao en Enxeñaría Civil, os contidos presentados poden serlle de utilidade a outros docentes ou profesionais do sector que desenvolvan a súa actividade no ámbito do deseño, construción ou conservación destas tipoloxías de infraestrutura do transporte.Universidade de Santiago de Compostela. Servizo de Normalización Lingüístic

A holistic methodology cum database for wave energy exploitation: implementation on the Galician coast (NW Spain)

Tese por compendio de publicaciónsPrograma Oficial de Doutoramento DO*MAR Marine Science, Technology and Management . 564V01[Abstract] The exploitation of the wave energy resource in a coastal region is based on the definition of two main aspects: the wave energy converter (WEC) and the location to install a wave farm. This decision making should be conducted on the basis of an accurate analysis of different factors, amongst which the power performance is fundamental. With this in view, in this thesis a holistic methodology far from the conventional approach is developed whose implementation in a coastal region produces a database containing the required information for accurately computing the power performance of any WEC at any coastal location. The methodology cum database is implemented on the Galician coast and a computer application developed so as to easily access and manipulate the large amount of information generated. As a result, the new decision-aid tool iWEDGE (intra-annual Wave Energy Diagram GEnerator) is available for the Galician coast, allowing the automatic reconstruction of annual and monthly high resolution characterization matrices at any coastal location, thereby providing the elements for a combined WEC-site selection.[Resumen] El aprovechamiento de la energía del oleaje en una región costera se basa en la definición de dos aspectos principales: el dispositivo convertidor de energía de las olas (WEC, wave energy converter) y la localización para instalar una planta de aprovechamiento undimotriz. Esta toma de decisiones debe ser realizada en base a un análisis de detalle de diferentes factores, entre los cuales el rendimiento energético es fundamental. Teniendo esto en consideración, en esta tesis se desarrolla una metodología holística que difiere en gran medida de los procedimientos convencionales, cuya implementación en una zona costera genera una base de datos que contiene la información necesaria para realizar estimaciones precisas del rendimiento de cualquier WEC en cualquier ubicación costera. La metodología cum base de datos se implementa en la costa gallega y se desarrolla una aplicación informática para acceder y manipular de modo sencillo la extensa información generada. Como resultado, la nueva herramienta de toma de decisiones iWEDGE (intra-anual Wave Energy Diagram GEnerator) está disponible para la costa gallega, la cual permite la reconstrucción automática de matrices de caracterización anual y mensual de alta resolución en cualquier localización costera, y por tanto proporciona los elementos para una selección combinada WECubicación.[Resumo] O aproveitamento da enerxía da ondada nunha rexión costeira baséase na definición de dous aspectos principais: o dispositivo convertedor de enerxía das ondas (WEC, wave energy converter) e a localización para instalar unha planta de aproveitamento undimotriz. Esta toma de decisións deber ser realizada en base a unha análise de detalle de diferentes factores, entre os cales o rendemento enerxético é fundamental. Tendo isto en consideración, nesta tese desenvólvese unha metodoloxía holística que difire en gran medida dos procedementos convencionais, que ó ser aplicada nunha determinada rexión xera unha base de datos que contén a información necesaria para realizar estimacións precisas do rendemento de calquera WEC en calquera localización costeira. A metodoloxía cum base de datos aplícase na costa galega e desenvólvese unha aplicación informática para acceder e manipular de modo sinxelo a extensa información xerada. Como resultado, a nova ferramenta de toma de decisións iWEDGE (intraanual Wave Energy Diagram GEnerator) está dispoñible para a costa galega, a cal permite a reconstrución automática de matrices de caracterización anual e mensual de alta resolución en calquera localización costeira, e por tanto proporciona os elementos para unha selección combinada WEC-ubicación

Experimental and numerical investigation of the hydrodynamic performance of an oscillating water column wave energy converter

The performance of an oscillating water column wave energy converter is investigated based on both numerical and experimental approaches. The viscosity effects are neglected in the numerical approach and the boundary integral equation method (BIEM) is implemented to solve the appropriate 2D boundary value problem (BVP). The influence of turbine damping and wave period is evaluated in the numerical model in both regular and random waves. A comprehensive experimental campaign is carried out in both regular and irregular waves to validate the numerical results as well as to investigate the influence of wave height, period and turbine damping on the efficiency of the converter. High and low turbine damping conditions are imposed to the experimental model. It is found that both the numerical and experimental results have a satisfactory agreement for the small wave amplitudes. It is detected that the efficiency of the device is very sensitive to the variations in the turbine damping although the absolute maximum efficiency is less sensitive to the slight alterations applied to the turbine damping. It is observed in the experimental study that the influence of the wave height has less importance than the other two parameters (turbine damping and incoming wave period) although the effect of the wave height becomes prominent in high wave amplitudes and causes the efficiency of the device to become less sensitive to variations in wave period and to tend to have an uniform value in wide wave period ranges.The work has been conducted within the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineering, which is financed by Portuguese Foundation for Science and Technology. The first author has been funded by the Portuguese Foundation for Science and Technology (Fundação para a Ciência e Tecnologia – FCT) under contract SFRH/BD/98287/2013. The experimental part of the work was conducted in the wave flume of the Hydraulics Laboratory integrated in the Group of Civil Engineering and Marine Energies (GICEMA), Escuela Politécnica Superior based on the scientific cooperation agreement between Instituto Superior Técnico and University of Santiago de Compostela.S

Análise a longo prazo da ondada

Titulación: Grao en Enxeñaría Civil -- Materia: Portos e CostasA presente Unidade Didáctica, Análise a longo prazo da ondada, encádrase dentro do Módulo I (Clima Marítimo) da materia de Portos e Costas do Grao de Enxeñería Civil. Neste primeiro módulo trátase a caracterización dos axentes climáticos que condicionan os procesos litorais e o deseño das actuacións no litoral, estes son: o vento, as ondas e as mareas. Seguidamente, no Módulo II (Procesos litorais) expóñense os principais procesos naturais que teñen lugar na costa e que determinan a xeomorfoloxía e a dinámica costeira. Finalmente, no Módulo III (Actuacións no litoral) abórdanse as diferentes tecnoloxías propias da enxeñaría de costas e portos. A ondada é un dos axentes climáticos máis significativos e complexos á hora de deseñar calquera actuación na costa. Para abordar o tema con suficiente grao de detalle, dedícanselle varias Unidades Didácticas na materia de Portos e Costas. Ó longo da Unidade Didáctica I defínese o seu mecanismo de xeración. Posteriormente, ó longo das Unidades II e III defínense os mecanismos físicos que interveñen na súa transformación e propagación cara a costa. Finalmente, nas Unidades IV e V trátanse as principais técnicas de análise que axudan á súa descrición e caracterización, necesarias para determinar as accións de cálculo nun proxecto de enxeñería de costas e portos. Unha vez definidas na unidade anterior as técnicas que determinan as características da ondada a curto prazo, esta Unidade dedícase ás técnicas de análise a longo prazo da ondada. Os contidos que aquí se desenvolven son necesarios para que o alumnado poida definir e/ou interpretar os réximes medio e extremo das ondas nunha localización determinada. Ó mesmo tempo, o alumnado adquirirá o coñecemento necesario para a resolución de dous problemas de enxeñería típicos: a estimación da operatividade portuaria e a estimación da ondada de proxecto dunha obra marítima.Universidade de Santiago de Compostela. Servizo de Normalización Lingüístic

Tidal stream energy potential in the Shannon Estuary

The tidal and river in-stream energy resource in the Shannon Estuary (W Ireland) is investigated using of high-resolution numerical modelling and spatial analysis. Although freshwater discharges are large, their influence on the available resource is found to be all but negligible, the tide being the main driver of estuarine circulation. The Tidal Stream Exploitability (TSE) index is adapted to the analysis of estuaries with non-depth-limited areas (TSEndl), such as the Shannon Estuary, and then used to select the hotspots with potential for a tidal stream farm. For this purpose, a new depth penalty-limiting function is defined to avoid overestimating the available energy potential in areas with depths greater than those required for tidal energy converter operation. Seven hotspots are identified based on the revised index. The approach followed in this study illustrates the applicability of high-resolution numerical modelling and spatial analysis for identifying the most appropriate areas for tidal stream energy conversion. Finally, the potential of tidal stream energy to contribute to the much-needed decarbonisation of the energy mix in Ireland is emphasizedThis work was funded by the PORTOS project co-financed by the Interreg Atlantic Area Programme through the European Regional Development Fund [grant number EAPA_784/2018] and ‘Axudas para a consolidación e estruturación de unidades de investigación competitivas nas universidades do Sistema Universitario Galego (2020-22)’ with reference number ED341B 2020/25. The authors are also grateful for the support of Science Foundation Ireland and MaREI, the Marine Renewable Energy Centre of Ireland, grant SFI MAREI2_12/RC/2302/P2 Platform RA1b. During this work I. López was supported by a postdoctoral grant of the ‘Programa de Axudas á etapa posdoutoral da Xunta de Galicia’ with reference number ED481D 2019/019S

Improvements in the design of nest cavities to attract cephalopods and crustaceans in a green artificial reef unit according to tridimensional hydrodynamic criteria – Application to the Ares-Betanzos estuary

[Abstract]: Installing artificial reefs (ARs) on the seabed creates a hard substrate that alters water flow and causes different species to settle. For this reason, by applying hydrodynamics to ARs, a useful tool is created for analysing these reefs so that there is adequate nutrient circulation and a propitious habitat for benthic and pelagic fauna. Using hydrodynamic criteria to characterise the velocity field, the present work aims to propose a methodology for positioning nest cavities within an AR unit in which different species will settle. Biological considerations, such as nutrient supply as well as the most suitable size and shape for the nest cavities, are taken into account. A stateof-the-art 3D shallow water model is validated and applied to the Ares-Betanzos estuary (NW Spain), where the installation of an AR group has recently been proposed. This coastal body, with a complex 3D hydrodynamic structure, was achieved under representative average conditions in absence of winds, which in turn greatly differs both in space and time throughout a spring-neap tidal cycle. A 3D CFD (Computational Fluid Dynamics) tool is applied to model food delivery on the AR. Moreover, the optimal geometry and position of nest cavities are established through a created indicator, ARnest cavity position, in order to provide sufficient nutrient circulation. It was found that the most appropriate shape for the nest cavities is cylindrical and a diameter of 200–300 mm is the most appropriate size. In terms of the ideal positions for the nest cavities, these depend on the orientation of the AR with respect to the current velocity. One of the orientations analysed leads to sufficient nutrient supply to the whole AR, while the other orientation analysed leads to sufficient nutrient supply to the high and mid positions at the front face, mid and low positions at the back face and all positions along the lateral faces.Xunta de Galicia; CN-10MMA003CTThis research was funded by Xunta de Galicia through the Project CN-10MMA003CT. This study was also funded through the collaboration agreement between the Xunta de Galicia (Convenio de colaboración entre a Xunta de Galicia, a Universidade da Coruña e a Fundación da Universidade da Coruña para dar continuidade ao Proxecto de investigación de arrecife artificial – PROARR), Universidade da Coruña and the Universidade da Coruña Foundation (FUAC) to give continuity to the previous project

Site-specific wave energy conversion performance of an oscillating water column device

The energy conversion performance of oscillating water column (OWC) wave energy converters at a specific site is often studied by means of analytical models. Based on linear theory, these models lose accuracy when viscous losses and turbulence become significant—more generally, when nonlinear effects play a role, as they often do in real operating conditions. In this work we apply a novel methodology based on a combination of numerical modelling and laboratory tests to investigate OWC performance without these shortcomings. First, high-resolution wave resource characterisation matrices are obtained by means of numerical modelling. Second, the resource matrices are combined with the OWC efficiency matrices obtained through laboratory tests and, importantly, including the effects of turbine-induced damping and air compressibility—usually disregarded in small-scale laboratory tests, but relevant for full-size (prototype) devices. The combined matrices thus obtained express, through a wave height-period distribution, the energy captured by the OWC for different values of the damping coefficient. On this basis, developers can select the most appropriate value of turbine-induced damping for a given site, based on performance values. The implementation of the novel methodology is illustrated through a case study in Galicia (NW Spain), in which three deployment sites are considered. We find that the turbine-induced damping must be matched to the wave climate of the site for an OWC device to achieve high performance; indeed, changes in damping cause variations in the total annual energy captured of up to 11%, which increase to 25% for specific sea states

Vento e xeración das ondas

Titulación: Grao en Enxeñaría Civil -- Materia: Portos e CostasA presente Unidade Didáctica, Vento e xeración das ondas, encádrase dentro do Módulo I (Clima Marítimo) da materia de Portos e Costas do Grao de Enxeñaría Civil. Neste primeiro módulo trátase a caracterización dos axentes climáticos que condicionan os procesos litorais e o deseño das actuacións no litoral, estes son: o vento, as ondas e as mareas. Seguidamente, no Módulo II (Procesos litorais) expóñense os principais procesos naturais que teñen lugar na costa e que determinan a xeomorfoloxía e a dinámica costeira. Finalmente, no Módulo III (Actuacións no litoral) abórdanse as diferentes tecnoloxías propias da enxeñaría de costas e portos. Neste Unidade Didáctica I (Vento e xeración das ondas) trátanse os distinto modelos de circulación do vento nas capas da atmosfera, a caracterización do vento a diferentes alturas e a súa actuación como elemento perturbador da superficie do mar propiciando a creación tanto de ondas, correntes ou incluso de mareas ou ondas largas.Universidade de Santiago de Compostela. Servizo de Normalización Lingüístic

Proposed Conceptual Framework to Design Artificial Reefs Based on Particular Ecosystem Ecology Traits

[Abstract] Overfishing and pollution have led to marine habitat degradation, and as a result, marine fisheries are now in decline. Consequently, there is a real need to enhance marine ecosystems while halting the decline of fish stocks and boosting artisanal fishing. Under these circumstances, artificial reefs (ARs) have emerged as a promising option. Nevertheless, their performance is traditionally assessed years after installation, through experimental and field observations. It is now necessary to adopt an alternative approach, adapting the design of artificial reefs to the specific characteristics of the ecosystem to be enhanced. In this way, it will be possible to determine the potential positive impacts of ARs before their installation. This paper presents a general and integrated conceptual framework to assist in the design of AR units by adopting an ecosystem ecology (EE) perspective. It consists of three main parts. In the first one, starting from an initial geometry, EE principles are used to include modifications with the aim of improving autotrophic resource pathways (additional substrata and increased nutrient circulation) and leading to a habitat enhancement (more shelter for individuals). The second part of the framework is a new dimensionless index that allows the user to select the best AR unit design from different alternatives. The potential impacts on the ecosystem in terms of energy, nutrient cycling and shelter are considered for such a purpose. Finally, a general hydrodynamic methodology to study the stability of the selected AR unit design, considering the effect of high waves under severe storms, is proposed. The framework is applied through a case study for Galician estuaries.The authors gratefully acknowledge the financial support from the regional government of Galicia, Xunta de Galicia, through the project CN-10MMA003CT. This study was also funded through the collaboration agreement between Xunta de Galicia, Universidade da Coruña and the Universidade da Coruña Foundation (FUAC) to give continuity to the previous projectXunta de Galicia; CN-10MMA003C

Numerical and experimental analysis of the velocity field inside an artificial reef. Application to the Ares-Betanzos estuary

[Abstract]: The placement of artificial reef (AR) units on the seabed modifies the velocity field of the water, making the nutrients circulate properly and creating the necessary habitat for the settlement of the desired species. This paper proposes a methodology for determining the circulation in the vicinity of one specific AR unit module previously defined in the existing literature. This has been based on both the application of three-dimensional hydrodynamic criteria and computational fluid dynamics (CFD) together with their validation using towing tank tests. In order to achieve the goals, the starting points are both the initial design of the AR units and the 3D hydrodynamic circulation model in the estuary. The latter predicts the nutrient supply to each module by taking into account the variation of speeds with height. From the vertical profile of circulation velocities, developed for each implantation site, a CFD tool is used to determine the circulation of nutrients in the vicinity of the AR unit, around 5 times the AR size. Then, the results are validated by carrying out towing tank experiments. The main contribution is to combine a circulation model of the estuary together with a CFD model validated with towing tank tests. Although this work was applied to the Ares-Betanzos estuary, it can be extrapolated to other zones worldwide.Xunta de Galicia ; CN-10MMA003C