As praias urbanizadas são ambientes complexos devido à interação da ocupação antropogênica e dos processos costeiros. A ocupação costeira vem se caracterizando por alteração e deterioração da paisagem, processo mais intenso em grandes cidades litorâneas, onde casas e edifícios são construídos nas proximidades imediatas da orla. O presente trabalho analisa a morfodinâmica e processo de sobrelavagem das praias de Santos e Itararé, duas praias urbanizadas com a presença de obras na orla. Foram realizados levantamentos topográficos nas praias e modelagem de ondas (Delft 3D - Wave) para toda a baía durante os anos de 2015 e 2016. Cenários de sobrelevaçãoonda e nível do mar foram estipulando para o cálculo da sobrelevaçãototal e assim conhecer as condições que levam a sobrelavagem. A baía de Santos encontra-se aberta para sul, expondo a linha de costa para a ação de frentes frias. A variabilidade do clima de ondas, derivada das mudanças das suas condições meteorológicas formadoras, pode alterar a morfologia da praia. Em Santos e São Vicente as ondas de sul e sudeste apresentam maiores alturas de onda e são mais frequentes no outono e inverno quando temos mais frentes frias na região. Os resultados indicam relação entre a incidência de ondas com maior força de onda (W/m), associadas a frentes frias, em trechos mais inclinados das praias com perda de volume. A variedade de incidência das ondas ao longo da praia estudada mostra um decréscimo na força de onda, sendo maior em Itararé e caindo em direção a Ponta da Praia, com a presença de picos altos na Ponta da Praia. Justificando porque este trecho sofre mais variação de volume e perda de sedimento fato que pode estar associado a dragagem do canal do porto de Santos. Em ambos os trechos com maior declividade e menor faixa de areia apresentaram maior sensibilidade à ação das ondas e também maior chance de sofrer sobrelavagem, de todo o arco praial da baía de Santos a porção leste de Santos se mostrou a mais propícia a sofrer inundação. / Urbanized beaches are more complex environments due to the interaction of anthropogenic occupation and coastal processes. Coastal occupation has been characterized by alteration and deterioration of the landscape, being more intense in large coastal cities, where houses and buildings are built in the immediate vicinity of the beach border being subject to potentially high risk of erosion. The present work analyzed the morphodynamics and overwashing of the beaches of Santos and Itararé, two urbanized beaches with the presence of anthropogenic constructions in the beach border. Topographic surveys on both beaches and wave modeling (Delft 3D - Wave) were carried out for the entire basin during the years of 2015 and 2016. Wave run-up and sea level scenarios were stipulated for the calculation of the total water level and so determined conditions that lead to overwashing. The bay of Santos is open to the South, exposing the coast line for the action of cold fronts. The variability of the wave climate, derived from the changes of its formative meteorological conditions, can alter the morphology of the beach. In Santos and São Vicente, South and Southeast waves have higher wave height and are more frequent in autumn and winter when we have more cold fronts in the region. The results indicate the direct relationship between the incidence of waves with higher wave force (W/m), associated with cold fronts, with loss of volume along the beaches. The variety of wave incidence along the studied beach shows a decrease in wave force, being higher in Itararé and falling towards Ponta da Praia, in the area protected by the rocky promontory. However in Ponta da Praia we see high values of wave force, justifying why this stretch suffers more volume variation and loss of sediment, that we belive happends because of Port Channel. In both stretches with greater slope and lower sand range showed greater sensitivity to the action of the waves and also greater chance of overwash, of all the praial arc of the Santos bay, the Eastern portion of Santos was the most propitious to suffer flooding.

O Rifte Continental do Sudeste do Brasil é uma das feições geotectônicas mais expressivas da margem continental brasileira e sua formação influenciou significativamente o padrão de transporte de sedimentos para as bacias marginais de Santos e Campos. Diferentes modelos foram propostos para a origem deste rifte e envolvem a reativação, como falhas normais, de zonas de cisalhamento Pré-Cambrianas. Não obstante, esses modelos são qualitativos e não existem experimentos numéricos que avaliaram a viabilidade dos mecanismos propostos para a origem do rifte. O presente trabalho teve como objetivo estudar a gênese deste rifte e analisar quantitativamente como diferentes fatores geológicos podem ter influenciado sua formação. Essa análise foi realizada numericamente a partir da simulação da evolução de uma margem divergente representativa do sudeste do Brasil. Foi utilizado um modelo numérico bidimensional que descreve a reologia da litosfera como um material viscoelástico de Maxwell na condição de deformação plana, permitindo analisar o estado de esforços na litosfera ao longo do tempo. Os fatores geológicos considerados nos testes numéricos incluíram erosão do continente, sedimentação ao longo da margem estirada, soerguimento regional induzido por uma anomalia térmica mantélica e esforço tectônico intraplaca relacionado ao empurrão pela expansão da cadeia meso-oceânica e orogenia andina. Esses fatores foram considerados separadamente e conjuntamente nos testes. Para avaliar o limite de ruptura das rochas foi considerado o critério de ruptura de Mohr-Coulomb para diferentes valores de coesão interna da rocha. Foi observado que, quando considerados separadamente, tanto a erosão como a sedimentação produziram um estado de esforços compatível com falhamento normal na região continental próxima à margem estirada. No entanto, o soerguimento regional induzido pela passagem de uma anomalia térmica na base da litosfera produz inexpressiva mudança da tensão deviatórica na crosta superior. O efeito sobreposto da erosão e da sedimentação no balanço de cargas sobre a litosfera produziu uma maior magnitude dos esforços resultando em uma condição suscetível à formação de falhas normais profundas, até o limite da crosta superior, na margem emersa. De modo semelhante, a sobreposição de uma compressão regional resultou em uma ligeira diminuição da profundidade do limite de ruptura para as rochas da crosta superior. Os resultados deste trabalho mostraram que o balanço de cargas devido à erosão da porção emersa do sudeste do Brasil e à sedimentação nas bacias marginais juntamente com baixos valores de coesão interna das rochas durante a evolução da margem divergente foram responsáveis por produzirem um estado de esforços na litosfera compatível com falhas normais profundas, e o efeito de um soerguimento regional causado por uma anomalia térmica assim como o efeito de uma compressão horizontal regional, não afetaram significativamente o estado de esforços de modo a alterar expressivamente a condição de ruptura das rochas ao longo da margem continental. / The Continental Rift of Southeastern Brazil is a remarkable feature at the Brazilian continental margin and its formation significantly influenced the sediment transport pattern to the Santos and Campos marginal basins. Several models were proposed to explain the genesis of the rift and involve the reactivation of Precambrian shear zones as normal faults. However, these models are qualitative and there is a lack of numerical experiments regarding the validity of the proposed mechanisms for the rift genesis. The aim of this work is to study the genesis of the rift and analyze quantitatively how different geological factors can affect its formation. The analysis were conducted through numerical simulations of the evolution of a divergent margin which represents the southeastern Brazil. The two-dimensional numerical model used to represent the lithospheric rheology by a Maxwell viscoelastic material in a state of plane strain and permits the analysis of the lithospheric state of stress throughout time. The geological factors considered in the numerical tests included the continental erosion, sedimentation, regional uplift induced by thermal mantle anomaly and the wide-plate tectonic stress due the ridge-push. These factors were considered separately and superimposed in the numerical tests. The Mohr-Coulomb criterion was adopted to calculate the failure condition, taking into account different values for the cohesion factor. Both erosion and sedimentation, when considered separately, produced a tectonic setting compatible with normal faulting near the stretched continental margin. However, the regional uplift due to the passage of a thermal anomaly on the base of the lithosphere didn\'t expressively affected the change of deviatoric stresses in the upper crust. The superimposed effect of erosion and sedimentation in the load balance on the lithosphere produced greater stresses magnitudes resulting in a favorable condition for the formation of deep normal faulting, up to the base of upper crust, under the onshore margin area. Similarly, the superimposed effect of compressive stresses resulted in the shallowing of the rupture limit of the upper crust. The results of this work showed that the load on the lithosphere due to erosion of the onshore continental area in the southeastern Brazil and the sedimentation on the marginal basins during the evolution of the margin were responsible to produce a state of stress in the lithosphere favorable to the formation of deep normal faulting and either the effect of regional uplift caused by a thermal anomaly or the compressive horizontal stresses didn\'t significantly influenced the state of stress to change the rupture condition of rocks along the continental margin.

The objective of this research was to evaluate the capabilities of ALEGRA, a Sandia National Labs hydrocode, and Forge3, a Transvalor S.A. product, to accurately model the Friction Stir Welding Process. ALEGRA and Forge3 are discussed in light of the inherent challenges of modeling Friction Stir Welding, and a rotational boundary condition is added to ALEGRA. Results are presented from Friction Stir Welding modeling outputs from both ALEGRA and Forge3. ALEGRA is shown to be incapable of modeling the Friction Stir Welding process, in large part due to its focus on shock propagation, which causes extremely small time steps. Forge3 is shown capable of modeling of the FSW plunge process in a transient manner, but overestimates the temperature profiles 90% to 100% in comparison to experimentally measured values. It appears that the adiabatic boundary condition is the source of much of the error. It is recommended that future work focus on improving estimates of the boundary conditions utilized in the Forge3 model.

The southern Chandeleur Islands are an ideal setting to study shoal evolution given their history of submergence and re-emergence. Here, numerical models shed light on the attendant processes contributing to shoal recovery/reemergence following a destructive storm event. Simulations of a synthetic winter storm along a cross-shore profile using Xbeach shows that convergence of wave-induced sediment transport associated with repeated passage of cold-fronts initiates aggradation, but does not lead to reemergence. A Delft3d model of the entire island chain shows that as these landforms aggrade alongshore processes driven by incident wave refraction on the shoal platform, backbarrier circulation and resulting transport become increasingly important for continued aggradation and eventual emergence. Aggradation magnitudes are a function of depth ranging from 2 – 10 mm per event (onset to recovery to near mean sea level). In the absence of big storms, this modest aggradation can be more than one meter in a few years.

The Discrete Element Method was first introduced by Cundall and Strack (1979) to model granular soils within the context of geotechnical engineering. The material is modeled as a random assembly of discrete elements. Each particle interacts with neighboring particles through contact forces that can be built up and broken at any time. The particles were modeled as discs in 2-D or as spheres in 3-D. Research studies have been conducted to improve the simulation of actual grain shapes. Ashmawy et al. (2003) developed the overlapping rigid clusters (ORC) method to accurately model irregular particle shapes. The idea relies on clumping a number of overlapping discs such that their coincides with that of the actual particle. In this dissertation, experimental verification program is presented. An experimental setup was built and model-grains were manufactured in the laboratory. A numerical simulation for the experimental test was carried out. The numerical and experimental results were compared qualitatively and quantitatively. A good agreement was observed within small displacements ranges. However, results were considerably different at large displacements. Numerical results utilizing the ORC method were closer to the experimental results than those of discs. A sequential and operator-independent procedure, which relies on the ORC concept, was developed. Identical inertial properties between the actual particle and the model were ensured. The new procedure was implemented for rounded and angular particles. The effect of particle shape and angularity on the strength and dilatancy characteristics of granular soils was investigated. A modified shape factor, which relies on the work introduced by Sukumaran and Ashmawy (2001), was developed. A series of pure shear testing simulations was performed on different shape and angularity particle groups. Angularity had a remarkable effect on strength and dilatancy properties compared to shape. The effect of interparticle friction on dilatancy was studied. An attempt was made to use an equivalent interparticle friction to model different particle shapes. It was concluded that there is no one-to-one equivalency between interparticle friction and shape or angularity. Instead, the interparticle friction must be continuously altered as a function of confining pressure and void ratio to achieve the required effect.

Numerical modeling systems are very important tools to study tidal inlets. In order to test its capability and accuracy of solving multi-inlet system problems, this study selected two widely used numerical modeling systems: Coastal Modeling System (CMS) and Delft3D Modeling Package. The hydrodynamics modules of the two modeling systems were tested at John's Pass and Blind Pass, Florida, a dual-inlets system, based on a similar modeling scheme. Detailed bathymetric surveys and hydraulic measurements were conducted to collect water depths, tide conditions, wave and current velocities as the input data as well as verification data for the models. A comparison study was conducted by comparing computed hydrodynamic results from both models with the extensive field measurement data. Results show that both of the modeling systems yield better prediction for water levels than for current velocity. Furthermore, under the similar modeling scheme, Delft3D was able to capture the measured tidal phase lag between the ocean boundary and the coastal inlet, therefore gave better water level prediction than the CMS model. However, the CMS yielded current velocities that are closer to the measured values than the DELFT3D model. CMS has a more user-friendly Graphic User's Interface (GUI) for input data preprocessing and plotting and visualization of output data. Delft3D has faster calculation speed.

In some continental shelf sediments integrated benthic microalgal biomass is greater than the integrated phytoplankton biomass in the overlying water column. In addition, benthic microalgae may account for up to 10% of the primary production responsible for the coastal fishery yield of the eastern United States. A three-dimensional model of the eastern Gulf of Mexico examines the effects of water-column nutrient sources on the growth of benthic microalgae. To parameterize the exchange of nutrients across the sediment/water interface in these permeable sediments, a non-local exchange submodel was constructed and tested within the framework of the model's grid. Based on the results of the three dimensional simulations, the growth of benthic microalgae from water-column nutrients is highly dependent on the light limitation of overlying phytoplankton. When light is available to phytoplankton in high enough quantities, water-column nutrients are used up before reaching the sediments. When the overlying phytoplankton are light limited, nutrients are able to reach the sediments where the shade adapted benthic microalgae can grow.

Estimation of effective diffusion coefficients is essential to be able to describe the diffusive transport of solutes in porous media. It has been shown in theory that in the case of uncharged porous materials the effective diffusion coefficient of solutes is a function of the pore morphology of the material and can be described by their tortuosity (tensor). To estimate the apparent diffusion coefficients, the values of tortuosity and porosity should be known first. In contrast with calculation of porosity, which can be easily obtained, estimation of tortuosity is intricate, particularly with increasing micro-geometry complexity in porous media. Moreover, many engineering materials (e.g, clays and shales) are characterized by electrical surface charges on particles of the porous material which can strongly affect the diffusive transport properties of ions. For these materials, estimation of effective diffusion coefficients have been mostly based on phenomenological equations with no link to underlying microscale properties of these charged materials although a few recent studies have used alternative methods to obtain the diffusion parameters. / In the first part of this thesis a numerical method based on a recently proposed up-scaled Poisson-Nernst-Planck type of equation (PNP) and its microscale counterpart is employed to estimate the tortuosity and thus the effective and apparent diffusion coefficients in thin charged membranes. Beside this, a new mathematical approach for estimation of tortuosity is applied and validated. This mathematical approach is also derived while upscaling of micro-scale Poisson-Nernst-Planck system of equations using the volume averaging method. A variety of different pore 2D and 3D micro-geometries together with different electrochemical conditions are studied here. To validate the new approaches, the relation between porosity and tortuosity has been obtained using a multi-scale approach and compared with published results. These include comparison with the results from a recently developed numerical method that is based on macro and micro-scale PNP equations. / Results confirm that the tortuosity value is the same for porous media with electrically uncharged and charged particles but only when using a consistent set of PNP equations. The effects of charged particles are captured by the ratio of average concentration to effective intrinsic concentration in the macroscopic PNP equations. Using this ratio allows to consistently take into account electro-chemical interactions of ions and charges on particles and so excludes any ambiguity generally encountered in phenomenological equations. / Steady-state diffusion studies dominate this thesis; however, understanding of transient ion transport in porous media is also important. The last section of this thesis briefly introduces transient diffusion through bentonite. To do so, the micro Nernst-Planck equation with electro-neutrality condition (NPE) is solved for a porous medium which consists of compacted bentonite. This system has been studied before in another research using an experimental approach and the results are available for both transient and steady-state phases. Three different conditions are assumed for NPE governing equations and then the numerical results from these three conditions are compared to the experimental values and analytical phenomenological solution. The tortuosity is treated as a fitting parameter and the effective diffusion coefficient can be calculated based on these tortuosity values. The results show that including a sorption term in the NPE equations can render similar results as the experimental values in transient and steady state phases. Also, as a fitting parameter, the tortuosity values were found varying with background concentration. This highlights the need to monitor multiple diffusing ion fluxes and membrane potential to fully characterize electro-diffusive transport from fundamental principles (which have been investigated in first part of this thesis) rather than phenomenological equations for predictive studies. / This research has lead to two different journal articles submissions, one already accepted in Computers and Geotechnics (October 22, 2009, 5-yrs Impact Factor 0.884) and the other one still under review.

This thesis investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, under co-operation with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. To numerically represent WEC effects the influence of the WECs upon the wave field was parameterized using the power absorption data from the WECs. Because a large driver of the WECs influence on the wave field is absorbed wave power by the WEC, it is reasonable to attempt a parameterization based on this process. It was of interest as to whether this parameterization, which does not account for wave scattering among other physics, could provide a good estimate of far-field effects. Accurately predicting WEC-array effects in the far-field requires empirical validation. Previous WEC analysis and modeling studies had limited data available for model verification, and additionally had used idealized WEC performance. In the present work we develop a WEC-array parameterization for use in phase-averaged wave models (e.g. SWAN). This parametrization only considers the wave absorption effects of the WECs and the model predictions of far-field effects are compared to observations. Further testing of the SWAN model was performed against a phase-resolving model, WAMIT, to determine the significance of physics the WEC absorption parameterization does not capture, such as scattered waves. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field. / Graduation date: 2013

Cyclonic oceanic vortices (eddies) ranging from ~10 to 150km in diameter that travel along the Florida Keys are investigated. This study employs hydrodynamic parameters from simulations in a high-resolution (~900m horizontally), three-dimensional (26 vertical levels) HYbrid Coordinates Ocean Model regional application to study coastal to offshore interactions along the Florida Keys. These parameters are compared qualitatively to observations from Chlorophyll-a Satellite (SEAWiFs) and HF Radar (WERA). Further, eddy characteristics along the Florida Keys are determined using the Okubo-Weiss parameter combined with Sea-Surface Height fields for the period 2004- 2008. Additionally, their temporal scales are assessed using spectral time-series analysis via Welch?s Fast Fourier Transform and Wavelet Transforms. Some processes that influence eddy evolution along the Florida Keys are presented in the form of case studies. And finally, the relative contribution of mesoscale and submesoscale eddies to the upwelling along the Florida Keys is assessed, supporting the argument that these features contribute to produce water exchanges between the offshore flow and the coastal areas.