A fundamental stage in rocky-shore seaweed life history is the recruitment process involving external fertilisation and then settlement of the propagules on a suitable substrate. The ultimate step in this settlement stage is the crossing of the viscous sub-layer and attachment to the substrate. Given the extreme conditions met in the intertidal zone, propagules can be dislodged at any time before they secure a strong enough anchoring. Flow conditions and propagule properties are key to this process. The settlement process under turbulent conditions was recreated within a stirred benthic chamber for five different species. Whereas propagule properties (size, density) vary with species, and propagules are adapted to the different conditions in the intertidal, they exhibit the same settlement behaviour. They nevertheless exhibit different settling velocities and settlement thresholds. Several methods of characterisation of the tank flow from particle tracking velocimetry and acoustic Doppler velocimetry data are reviewed, as well as an analytical model. Turbulent settling was found to be independent of the well-mixed tank bulk flow and to depend only on the boundary-layer mechanics. A model of settlement threshold is presented from which propagule mucilage adhesiveness estimates are derived, leading to good correlations between adult plant exposure and the stickiness of its propagules and to the conclusion that settlement can only occur in calm conditions. To extend the work, computational fluid dynamic techniques are developed by extending the Gerris Flow Solver. A 2-D approach to tank modelling and a pilot study of expansion to 3-D is described. This extends the perspective given by the experiments, notably through output of the hydrodynamical forces experienced by the propagules. Finally, in the view of realizing direct numerical simulations of propagule behaviour in the viscous sub-layer, a new and unique 2-D/3-D fully conservative solid/fluid interaction model is developed and tested with success.

This thesis presents a two-phase liquid-solid numerical model using Smoothed Particle Hydrodynamics (SPH). The scheme is developed for multi-phase flows in industrial tanks containing sediment used in the nuclear industry for decommissioning. These two-phase liquid-sediments flows feature a changing interfacial profile, large deformations and fragmentation of the interface with internal jets generating resuspension of the solid phase. SPH is a meshless Lagrangian discretization scheme whose major advantage is the absence of a mesh making the method ideal for interfacial and highly non-linear flows with fragmentation and resuspension. Emphasis has been given to the yield profile and rheological characteristics of the sediment solid phase using a yielding, shear and suspension layer which is needed to predict accurately the erosion phenomena. The numerical SPH scheme is based on the explicit treatment of both phases using Newtonian and non-Newtonian Bingham-type constitutive models. This is supplemented by a yield criterion to predict the onset of yielding of the sediment surface and a suspension model at low volumetric concentrations of sediment solid. The multi-phase model has been compared with experimental and 2-D reference numerical models for scour following a dry-bed dam break yielding satisfactory results and improvements over well-known SPH multi-phase models. A 3-D case using more than 4 million particles, that is to the author’s best knowledge one of the largest liquid-sediment SPH simulations, is presented for the first time. The numerical model is accelerated with the use of Graphic Processing Units (GPUs), with massively parallel capabilities. With the adoption of a multi-phase model the computational requirements increase due to extra arithmetic operations required to resolve both phases and the additional memory requirements for storing a second phase in the device memory. The open source weakly compressible SPH solver DualSPHysics was chosen as the platform for both CPU and GPU implementations. The implementation and optimisation of the multi-phase GPU code achieved a speed up of over 50 compared to a single thread serial code. Prior to this thesis, large resolution liquid-solid simulations were prohibitive and 3-D simulations with millions of particles were unfeasible unless variable particle resolution was employed. Finally, the thesis addresses the challenging problem of enforcing wall boundary conditions in SPH with a novel extension of an existing Modified Virtual Boundary Particle (MVBP) technique. In contrast to the MVBP method, the extended MVBP (eMVBP) boundary condition guarantees that arbitrarily complex domains can be readily discretized ensuring approximate zeroth and first order consistency for all particles whose smoothing kernel support overlaps the boundary. The 2-D eMVBP method has also been extended to 3-D using boundary surfaces discretized into sets of triangular planes to represent the solid wall. Boundary particles are then obtained by translating a full uniform stencil according to the fluid particle position and applying an efficient ray casting algorithm to select particles inside the fluid domain. No special treatment for corners and low computational cost make the method ideal for GPU parallelization. The models are validated for a number of 2-D and 3-D cases, where significantly improved behaviour is obtained in comparison with the conventional boundary techniques. Finally the capability of the numerical scheme to simulate a dam break simulation is also shown in 2-D and 3-D.

L'utilisation extensive des matériaux composites dans l'industrie aéronautique nécessite une compréhension étendue de leur comportement mécanique et mécanismes d'endommagement. La prise en compte des effets environnementaux, température et vieillissement humide, dans la prévision du comportement à l'impact, des endommagements et des mécanismes associés reste un sujet encore peu traité actuellement. Dans ce travail différentes conditions de vieillissement humide (dénommées ci-après état neuf, 65% VH, et 90%VH) ont été appliquées au matériau de l'étude. La caractérisation des propriétés du pli et de l'interface ont été effectuée à température ambiante et 80°e. Une attention particulière a été portée à l'identification des propriétés en cisaillement plan. Un modèle d'endommagement progressif basé sur la mécanique de l'endommagement dans les milieux continus est proposé afin de décrire au mieux le comportement du pli élémentaire en prenant en compte les comportements fortement non-linéaires identifiés pour le cisaillement plan de ce matériau. Ce modèle matériau de comportement du pli est combiné avec des lois cohésives d'interface inter-laminaire utilisés dans des simulations numériques d'impact à faible vitesse afin de prédire la réponse mécanique à l'impact et les dommages. Le modèle de matériau a été implémenté dans le code de calcul explicite LS-Dyna. Des essais d'impact à différentes énergies ont été effectués afin de valider par comparaison essais-calcul l'approche utilisée. Une bonne adéquation est observée entre les résultats numériques et expérimentaux du matériau non-vieilli et testé à température ambiante pour ce qui concerne l'historique de la réponse globale et les dommages internes (rupture de fibre, fissures de matrice et délaminages). / The extensive application of composite laminates in aeronautical industries demands a thorough understanding of their mechanical behaviours and damage. The prediction of impact behaviour, impact damage and the associated mechanisms under complex environmental effects remain still an open issue. The effects of various humid ageing conditions (No ageing, 65% relative humidity and 90% relative humidity ageing) and environ mental temperatures (room temperature and 80°C) on the intra-Iaminar and inter-Iaminar properties are characterized. A particular emphasis is laid on the study of different non linear behaviours of in plane shear. A progressive damage model based on continuum damage mechanics is proposed to describe intra laminar mechanical behaviour by taking into account the identified in-plane shear nonlinear phenomenon. This model is then applied in numerical simulation on low velocity impact combined with cohesive law in interface to predict the impact response and associated damage (ie. Fibre failure, matrix cracks and delaminations). The damage model is implemented in LS Dyna as user defined material laws.lmpact tests on laminate coupons with different stratifications are performed to validate the numerical simulation. Good agreement is achieved especially for nonaged material under room temperature between numerical and experimental results in terms of contact force history, platedeflection and impact duration. By means of non-destructive inspection, the impact damage is coherent with predicted results concerning fiber damage location, matrix cracks especially the through thickness delamination.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / In this thesis, we presents a development and validation of a 3D numerical model for the advection-diffusion equation. Models of this kind has been developed for scientific investigations and to support atmospheric emissions control and environmental policy decisions. To develop this model, we used the computational implementation of an explicit numerical scheme for the discretization of the envolved equations. During this procedures, exaustive tests were performed to ensure that the used implementations agrees to the stability, consistence and convergence criterias. As a way for minimizing one of the main deficiences found in almost the major atmospheric dispersion models, i.e. imprecisions in the meteorological input data for initializing this models, we used a realistic atmospheric flow field generated by mesoscale circulation model. As the mesoscale model gives information at scale larger than the necessary for description of a plume trajectory, a weighted linear average proper interpolation was developed for intermediate these distances. Our model considers the assumption that atmospheric turbulence is not isotropic, where diffusion coefficients are variables in time and space and are different for lateral and vertical directions. In our model we estimate this coefficients by the atmospheric boudary layer parameterizations proposed byMoraes (2000). For validation of themodel, we used experimental datasets from field experiment carried near a thermoelectric power plant presidente Médici, in the city of Candiota/RS. These datasets contains surface SO2 concentrations, surface wind velocity measured in meteorological towers as well as turbulence data measured in micrometeorological towers. The results of the validation indicates that the model works well, at least for the source and the terrain were it is located. i.e. continuous emission and homogeneous topography. / Nesta tese, apresentamos o processo de desenvolvimento e validação de um modelo numérico 3D para a equação de difusão-advecção. Modelos como este têm sido desenvolvidos objetivando a investigação científica para dar suporte ao controle de emissões de poluentes atmosféricos e à tomada de decisões no desenvolvimento de políticas ambientais. Para a elaboração deste modelo utilizamos a implementação de um esquema numérico explícito na discretização das equações envolvidas. Durante este processo, exaustivos testes foram realizados para que a implementação garantisse estabilidade, consistência e convergência. Como forma de minimizar uma das principais deficiências encontradas na maioria dos modelos de dispersão atmosféricos (MDA), qual seja, a imprecisão da entrada de dados meteorológicos para a inicialização destes modelos, utilizamos um campo de vento realístico gerado por um modelo numérico de circulação de mesoescala. No entanto, como este modelo de mesoescala fornece informações com uma escala maior do que a necessária para a descrição da trajetória de uma pluma, foi preciso desenvolver um método de interpolação apropriado para intermediar estas distâncias. Nosso modelo contempla, ainda, a hipótese da turbulência atmosférica não ser isotrópica, onde os coeficientes de difusão turbulenta são variáveis no tempo e espaço e, ainda, diferentes nas direções lateral e vertical. Em nosso modelo, estes coeficientes foram estimados utilizando a parametrização de camada limite proposta por Moraes (2000). Para a validação do modelo, utilizamos dados experimentais obtidos em um experimento realizado próximo à usina termelétrica Presidente Médici, no município de Candiota/RS. Estes dados compreendem medidas de concentração superficial de SO2, velocidade do vento em superfície medidos em torres meteorológicas, bem como dados de turbulência medido em torre micrometeorológica. Os resultados da validação mostraram que o modelo funciona bem, ao menos para o tipo de fonte e topografia onde está localizada, ou seja, emissão contínua e topografia homogênea.

A presente tese versa sobre ampla investigação em torno da distribuição das ações verticais entre paredes de alvenaria estrutural dentro de um edifício. O edifício foi caracterizado como pertencente ao sistema complexo de paredes, o qual é de uso mais comum no Brasil. Desenvolveu-se análise numérica no edifício, com objetivo de predizer o comportamento na análise experimental, assim como na comparação entre os próprios modelos numéricos. Serviu de modelo experimental um edifício em escala real, o qual foi monitorado, durante sua execução e depois dela, com ensaio de prova de carga. Realizou-se monitoramento mediante uso de unidades especiais de alvenaria instrumentadas para se converterem em células de carga, nas quais as tensões em cada ponto de análise puderam ser determinadas. Tabelas e gráficos foram montados para tornarem possível a verificação das diferenças entre todos os modelos analisados. Como principais conclusões uma se mostrou de grande importância e foi esta: as paredes sofrem efeito da flexão e a causa são as rotações nas lajes apoiadas por elas. / The present thesis contemplated a wide investigation about the vertical action distribution among structural masonry walls within a building. The building was characterized as related to the complex system of walls, which practice is the most customary in Brazil. It was developed a numerical analysis in the building aiming to predict the structural behavior on the experimental analysis, as well as a comparison among numerical models themselves. The experimental model consisted on a real scale building, which was monitored during its execution and after that, with a live load test. The monitoring was done with the usage of special masonry units, which were instrumented to convert itself in a load cell, on which the stress in each point of analysis could be determined. Tables and graphics were mounted to make feasible to verify the differences among all models analyzed. As main conclusions observed, one showed to be of great importance, which was the effect of bending on the walls caused by the rotations on the slabs supported by them.

A utilização de concreto projetado como suporte de túneis é uma prática amplamente difundida no mundo inteiro. Este tipo material possui a característica de começar a agir estruturalmente desde pequenas idades. Apesar disso, os correntes processos de dimensionamento de suportes negligenciam o desenvolvimento de suas propriedades com o tempo, em acoplamento aos efeitos tridimensionais da região onde se localiza a frente de escavação. O presente trabalho tem a finalidade de relatar os procedimentos utilizados na análise da influência de alguns parâmetros da interação maciço - suporte, sobre os esforços solicitantes e os deslocamentos radiais finais do suporte de um túnel, tanto para o caso de concreto projetado, com suas propriedades dependentes do tempo, quanto para materiais com propriedades constantes. São elaboradas soluções adimensionais para o problema da quantificação de esforços solicitantes no suporte e de deslocamentos radiais na interface entre maciço e suporte. Além disso, é proposta uma forma de se determinar, através destas soluções adimensionais, coeficientes de alívio de tensões que auxiliam em simulações bidimensionais de escavações subterrâneas. / The utilization of shotcrete as tunnel support is a widely diffused practice in the whole world. This kind of material has the feature of beginning to act structurally since early ages. Nevertheless, the current processes of support design neglect the development of its properties after some time in connection to the 3D effects of the region where the face of the tunnel is located. The present work relates the procedures adopted in analyzing the influence of some ground-support interaction parameters on the support internal forces and interface radial displacements of a tunnel, not only when shotcrete is used, with its time-dependent properties, but for materials with constant properties as well. Dimensionless solutions are developed for the support thrust and radial displacement quantification problem. Moreover, through this dimensionless solution, a way of quantifying stress relief factors, which are intermediate steps in 2D simulations of underground excavations, is proposed.

Orientador: Luiz Felipe Mendes de Moura / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T21:08:34Z (GMT). No. of bitstreams: 1 Brandao_MatheusMarcelino_M.pdf: 452664 bytes, checksum: 124f6ab109716c77cffe6f192c006b30 (MD5) Previous issue date: 2005 / Resumo: No presente trabalho se realiza o estudo e desenvolvimento de um modelo numérico computacional com a finalidade da simulação de sistemas de refrigeração por compressão de vapor. Em um primeiro momento, foram analisados e discutidos os principais tipos de modelamento para cada componente do sistema de refrigeração (compressor, condensador, válvula de expansão e evaporador) encontrados na literatura. Após esta primeira análise, foram escolhidos os modelos utilizados para o desenvolvimento do programa computacional. O programa foi validado a partir da comparação dos resultados obtidos numericamente com os obtidos em ensaios experimentais. Após a validação, foram feitos dois estudos de casos, para a verificação da influência dos parâmetros sobre os sistemas simulados e otimização do desempenho de tais sistemas / Abstract: This work performs the study and development of a numerical computational model in order to simulate refrigeration systems by steam compression. At first, the main types of modelation for each component of the refrigeration system (compressor, condenser, expansion valve and evaporator) found in literature are analysed and discussed. After this first analysis, the models for the development of a computational program are chosen. The program is validated by means of the comparison of the results obtained numerically with those acquired in experimental tests. Just after validation, two studies of cases are made to verify the influence of the parameters on the simulated systems and to optimize the performance of those systems / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Syfte med examensarbetet har varit att upprätta en grundvattenmodell överEnköpingsåsen med hjälp av programvaran MODFLOW för att därefter försöka skattagrundvattenmagasinets parametrar. Parameterskattningen utfördes med detmodelloberoende programmet PEST. Parallellt med detta gjordes även enpumptestutvärdering av dessa parametrar där typkurvor passades till en tidigare utfördprovpumpning av akviferen. Därefter jämfördes dessa båda metoder. Vidare utfördesäven en känslighetsanalys av grundvattenmodellen i MODFLOW för att försökalokalisera nya undersökningsplatser.Grundvattenmodellen uppfördes över Enköpingsåsen i och kring Enköping. Där är åsenlokaliserad i nord sydlig riktning och strax söder om Enköpings centrala delar korsasåsen av Enköpingsån. Det råder osäkerhet angående grundvattenmagasinetsvattenbalans och var åsen får sitt tillskott av vatten ifrån. Enköpingsåsen fungerar somhuvudvattentäkt i Enköpings stad vilket gör att detta har ansetts viktigt att utreda.Grundvattenmodellen byggdes upp genom att främst använda redan insamlad data frångeotekniska, geofysiska och hydrogeologiska undersökningar utförda i området samtdata från SGU och SMHI. Därifrån togs data om områdets uppbyggnad och struktursamt dess yttre betingelser som till exempel nederbörd och Mälarens vattenstånd för attskapa en numerisk modell i MODFLOW.Resultaten visar på ett överensstämmande resultat mellan parameterskattningen gjord iMODFLOW och pumptestutvärderingen. Vidare tyder resultaten i MODFLOW på attde största osäkerheterna i modellen ligger kring Enköpingsån och är då beroende av omvattnet tillförs från grundvattenmagasinets laterala delar eller från Enköpingsån.Känslighetsanalysen tyder även på att för ytterligare undersökningar av åsenshydrogeologiska betingelser bör fokus ligga på förhållandena i Enköpingsåns sedimentoch dess genomsläpplighet. / The purpose of this thesis is to establish a groundwater model of the Enköping eskerusing MODFLOW simulation and then estimate groundwater parameters with themodel-independent program PEST. In parallel, a pump test evaluation of theseparameters where type curves are fitted to a previously performed pump test of theaquifer is done to estimate the aquifer parameters. Eventually, these two methods arecompared. Furthermore, a sensitivity analysis of the groundwater model is performed totry to locate additional measurement points.The groundwater model was built for the Enköping esker in and around Enköping. Theesker is located in the north-south direction and just south of Enköpings central partswhere Enköpingsån crosses the esker. There is uncertainty regarding the water balanceof the aquifer and where the esker recharges its water from. Enköping esker serves asthe main water source in Enköping city and this is why it is considered important toinvestigate.The groundwater model was constructed primarily by using already collected data fromgeotechnical, geophysical and hydrogeological studies conducted in the area as well asdata from the SGU and SMHI. The data on the area's composition and structure as wellas its external conditions is taken to create a numerical model in MODFLOW.The results show consistent outcomes between parameter estimates made withMODFLOW/PEST and the pump test evaluation.The results made with MODFLOW makes it possible to do further analysis. Resultsshow large model uncertainties around Enköpingsån and the esker is dependent onwater supplied from either the groundwater aquifer’s lateral parts or Enköpingsån. Thesensitivity analysis also suggests that further studies of the hydrogeological conditionsshould be concentrated to Enköpingsån’s sediments and its water penetration capacity.

This master’s thesis deals with exploring present conditions in Maloměřice-Brno during floods which is followed by design of antiflood protective structures. Research uses coupled 1D/2D numerical model for flood discharges Q1, Q5, Q20 and Q100 computing. In the last step maps of hazard and draw documentation were made.

Philosophiae Doctor - PhD / Research findings in current study provide a new insight into the fractured rock aquifers in the TMG area. Some of the results will have wide implications on the groundwater management and forms a solid basis the further study of the TMG aquifers.