Two surface-based, portable, S-band and C-band polarimetric scatterometers intended for in situ measurements of both terrain and the ocean’s surface are presented. The scatterometers' layout, hardware design, measurement accuracy, calibration, and signal processing concepts are described. To augment in situ geophysical observations, researchers have often employed in situ scatterometers for validating satellite-based retrievals and also for their innate ability to monitor geophysical variations of localized regions with fine temporal resolution. Backscatter measurement variability due to system effects is presented, providing the fundamental basis for the quantitative analysis of data. Sample polarimetric retrievals are presented for asphalt pavement and grass.

The NASA Scatterometer (NSCAT) was launched August 20, 1996 aboard the National Space Development Agency of Japan's Advanced Earth Observing Spacecraft (ADEOS). NSCAT's primary mission was to measure radar backscatter over the world's oceans. These measurements are used to generate estimates of ocean wind speed and direction. Scatterometers must be calibrated before their measurements are scientifically useful. However, the calibration of NSCAT must be done in orbit. A new methodology for selecting land regions for use in extended target spaceborne scatterometer calibration is first developed. Next, a summary of the calibration technique used in this thesis is presented. While the foundation of this technique was previously developed theoretically, the work in this thesis is its first application for calibration/validation of an on-line spaceborne radar system. The technique is extended to estimate simultaneously NSCAT's calibration and the host spacecraft's attitude error. The attitude references reported by the attitude control system on-board ADEOS are deemed erroneous. Results of this expanded technique, applied under varying assumptions, are presented for consideration. A summary and suggestions for future research conclude this work.

The electromagnetic (EM) bias is the largest source of error in the TOPEX/Poseidon and Jason-1 satellite sea surface height (SSH) estimates. Due to incomplete understanding of the physical processes which cause the bias, current operational models are based on empirical relationships between the bias wind speed and significant wave height. These models reduce RMS estimation errors of the EM bias to approximately 4 cm. To improve EM bias estimation the correlation between the bias and RMS long wave slope is studies using data from tower-based experiments in the Gulf of Mexico and Bass Straight, Australia. Models based on significant wave height and RMS slope are more accurate than models based on wave height and wind speed by at least 50% in RMS error between predicted and ground truth bias values. Nonparametric models have been proposed as a method to reduce the variability of EM bias estimates. Using tower data, nonparametric models developed from wind speed and significant wave height measurements are shown to provide some improvement over parametric models. It is also shown that the historical discrepancy between satellite and tower EM bias measurements is reduced by nonparametric modeling. A validity study of rough surface scattering models is conducted for surfaces with Gaussian and power law power spectra. Models in the study include physical optics (PO), geometrical optics, small perturbation method, and small slope approximation. Due to the prevalence of the PO approximation, particular emphasis is placed on the development of a validity criterion for the PO model. An empirical study of the PO approximation shows that the validity of the model is more accurately described by the RMS wave slope than the classic surface curvature criterion for surfaces with a Gaussian power spectrum. For surfaces with a power law PSD, the accuracy of the PO approximation is related to the significant slope (RMS surface height/wavelength of the dominant spectral peak). The validity of other models in the study are also shown to be well approximated by bounds on surface slope. An EM bias model is derived using the physical optics scattering model, hydrodynamic modulation, and non-Gaussian long wave surface statistics. Using a modulation transfer function, the hydrodynamic modulation of small wave heights is shown to be linearly related to the long wave RMS slope. The resulting EM bias model expresses the relative bias as a function of the long wave surface parameters RMS wave slope, surface skewness, and tilt modulation. Coefficients of the long wave parameters are determined by the short ocean waves, and provide insight into the physical mechanisms that cause the bias. From measured values of the ocean surface profile, estimated values of the bias are computed from the bias model. A comparison of these estimated values with in situ EM bias measurements shows a strong correlation between the estimated and measured values. Nadir and off-nadir measurements of the EM bias collected during the BYU Off-Nadir Experiment (Y-ONE) are presented. The in situ measurements are compared with bias estimates computed from an off-nadir generalization of the nadir EM bias model. From theoretical and experimental bias measurements a model of the angular dependence of the bias is developed as a function of the normalized bias at nadir.

The SeaWinds scatterometers aboard the QuikSCAT and ADEOS II satellites were originally designed to measure wind vectors over the ocean by exploiting the relationship between wind-induced surface roughening and the normalized radar backscatter cross-section. Recently, an algorithm for simultaneously retrieving wind and rain (SWR) from scatterometer measurements was developed that enables SeaWinds to correct rain-corrupted wind measurements and retrieve rain rate data. This algorithm is based on co-locating Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) and SeaWinds on QuikSCAT data. In this thesis, a new wind and rain radar backscatter model is developed for the SWR algorithm using a global co-located data set with rain data from the Advanced Microwave Scanning Radiometer (AMSR) and backscatter data from the SeaWinds scatterometer aboard the Advanced Earth Observing Satellite 2 (ADEOS II). The model includes the effects of phenomena such as backscatter due to wind stress, atmospheric rain attenuation, and effective rain backscatter. Rain effect parameters of the model vary with integrated rain rate, which is defined as the product of rain height and rain rate. This study accounts for rain height in the model in order to calculate surface rain rate from the integrated rain rate. A simple model for the mean rain height versus latitude and longitude is proposed based on AMSR data and methods of incorporating this model into the SWR retrieval process are developed. The performance of the new SWR algorithm is measured by comparison of wind vectors and rain rates to the previous SWR algorithm, AMSR rain rates, and NCEP numerical weather prediction winds. The new SWR algorithm produces accurate rain estimates and detects rain with a low false alarm rate. The wind correction capabilities of the SWR algorithm are effective at correcting rain-induced inaccuracies. A qualitative comparison of the wind and rain retrieval for Hurricane Isabel demonstrates these capabilities.

Residual stress measurement methods have commonly been used to characterize states of stress in various elastic isotropic materials. In order to investigate the effects of elastic anisotropy on residual stress measurements, commercially pure grade 2 titanium (CP Ti Gr 2) was selected to study a strong texture, or preferred grain orientation. Warm rolled and air-cooled CP titanium is well known to have a texture from the factory. This texture and resulting elastic anisotropy were confirmed using two material characterization methods, resonant ultrasound spectroscopy (RUS) and electron backscatter diffraction (EBSD). The texture was further developed using a rolling mill to cold roll the titanium. A vacuum furnace set to a temperature of 550 C for one hour was used to stress relieve the titanium without reducing the texture. RUS and EBSD methods were used again to confirm the texture achieved by cold rolling. Well-characterized residual stresses were introduced with a shrink-fit ring and plug. The residual stress hole drilling method was used to characterize stresses in the rolling and transverse directions of the ring and plug assemblies. Stress profiles from hole drilling indicated some possible elastic anisotropic effects in two assemblies and are presented. However, more assemblies are needed to confirm the results. A stress determination technique with higher sensitivity may be necessary to substantiate assembly stress profile results.

This work establishes a framework for Monte Carlo simulations of complex, modulated electron fields produced by Varian's TrueBeam medical linear accelerator for investigations into modulated electron radiation therapy (MERT) and combined modulated photon and electron radiation therapy (MPERT). Both MERT and MPERT have shown potential for reduced low dose to normal tissue without compromising target coverage in the external beam radiation therapy of some breast, chest wall, head and neck, and scalp cancers. This reduction in low dose could translate into the reduction of immediate radiation side effects as well as long term morbidities and incidence of secondary cancers. Monte Carlo dose calculations are widely accepted as the gold standard for complex radiation therapy dose modelling, and are used almost exclusively for modelling the complex electron fields involved in MERT and MPERT. The introduction of Varian's newest linear accelerator, the TrueBeam, necessitated the development of new Monte Carlo models in order to further research into the potential role of MERT and MPERT in radiation therapy. This was complicated by the fact that the field independent internal schematics of TrueBeam were kept proprietary, unlike in previous generations of Varian accelerators. Two approaches are presented for performing Monte Carlo simulations of complex electron fields produced by TrueBeam. In the first approach, the dosimetric characteristics of electron fields produced by the TrueBeam were first compared with those produced by an older Varian accelerator, the Clinac 21EX. Differences in depth and profile characteristics of fields produced by the TrueBeam and those produced by the Clianc 21EX were found to be within 3%/3 mm. Given this information, complete accelerator models of the Clinac 21EX, based on its known internal geometry, were then successfully modified in order to simulate 12 and 20 MeV electron fields produced by the TrueBeam to within 2%/2 mm of measured depth and profile curves and to within 3.7% of measured relative output. While the 6 MeV TrueBeam model agreed with measured depth and profile data to within 3%/3 mm, the modified Clinac 21EX model was unable to reproduce trends in relative output as a function of field size with acceptable accuracy. The second approach to modelling TrueBeam electron fields used phase-space source files provided by Varian that were scored below the field-independent portions of the accelerator head geometry. These phase-spaces were first validated for use in MERT and MPERT applications, in which simulations using the phase-space source files were shown to model depth dose curves that agreed with measurement within 2%/2 mm and profile curves that agreed with measurement within 3%/3 mm. Simulated changes in output as a function of field size fell within 2.7%, for the most part. In order to inform the positioning of jaws in MLC-shaped electron field delivery, the change in output as a function of jaw position for fixed MLC-apertures was investigated using the phase-space source files. In order to achieve maximum output and minimize treatment time, a jaw setting between 5 and 10 cm beyond the MLC- field setting is recommended at 6 MeV, while 5 cm or closer is recommended for 12 and 20 MeV with the caveat that output is most sensitive to jaw position when the jaws are very close to the MLC-field periphery. Additionally, output was found to be highly sensitive to jaw model. A change in divergence of the jaw faces from a point on the source plane to a 3x3 mm^2 square in the source plane changed the shape of the output curve dramatically. Finally, electron backscatter from the jaws into the monitor ionization chamber of the TrueBeam was measured and simulated to enable accurate absolute dose calculations. Two approaches were presented for measuring backscatter into the monitor ionization chamber without specialized electronics by turning o the dose and pulse forming network servos. Next, a technique was applied for simulating backscatter factors for the TrueBeam phase-space source models without the exact specifications of the monitor ionization chamber. By using measured backscatter factors, the forward dose component in a virtual chamber was determined and then used to calculate backscatter factors for arbitrary fields to within 0.21%. Backscatter from the jaws was found to contribute up to 2.6% of the overall monitor chamber signal. The measurement techniques employed were not sensitive enough to quantify backscatter from the MLC, however, Monte Carlo simulations predicted this contribution to be 0.3%, at most, verifying that this component can be neglected. / Graduate / 0756 / lloyd.samantha@gmail.com

Os órgãos de saúde internacionais e nacionais, como o Ministério da Saúde na portaria 453/98 da Vigilância Sanitária, exigem que a Dose de Entrada na Pele seja avaliada para cada equipamento mamográfico através da leitura de um sistema câmara de ionização-eletrómetro corrigida pelo fator de retroespalhamento. Ao não existir menção explícita na portaría de valores utilizáveis para o fator de retroespalhamento, este trabalho visa à determinação experimental do fator de retroespalhamento, através da utilização dos dosímetros termoluminescentes TLD-100. No estudo são verificadas as dependências geométricas e espectrais do fator de retroespalhamento, assim como do valor da Dose de Entrada na Pele, e da Dose em Profundidade, correspondentes com as técnicas radiográficas empregadas nos exames mamográficos convencionais de rotina. Foram avaliados feixes na faixa de 0,35 mmAl até 0,43 mmAl, tensões do tubo de 25kV, 28kV, 30kV, e 32kV, assim como os três tamanhos de campo disponíveis no Mamógrafo Senographe DMR utilizado, e distancias focofilme iguais a 56cm, 61cm e 66cm. Os resultados obtidos foram comparados com publicações existentes, as quais apresentam resultados obtidos através de Simulação Monte Carlo, câmaras de ionização, e dosímetros TLD-100. Os resultados obtidos neste trabalho permitem estabelecer e discutir as dependências das grandezas dosimétricas estudadas com a Camada Semi-Redutora, tensão do tubo, combinação ânodo-filtro, tamanho de campo, distância foco-filme e espessura da mama. / National and international health organizations such as the Brazilian Ministry of Health, through its Secretary of Health Surveillance establishes in the publication Nº 453/98 that in all mammographic equipments must be evaluated the entrance-skin dose through the readings of an ionization chamber-electrometer system corrected by the backscatter factor, among others factors. Nevertheless, there is no explicit mention for useful values of backscatter factor in this document; the main aim of this work is the experimental determination of backscatter factor through the use of TLD-100 dosimeters. In this study, the geometric and spectral dependencies of the backscatter factor, entrance-skin dose and the in-depth dose were evaluated, corresponding to the most radiographic techniques employed in conventional mammographic procedures, i.e., beam qualities in the range of 0.35 mmAl to 0.43 mmAl, tube voltages from 25kV to 32kV, focus-film distances from 56cm to 66cm, and three field sizes were evaluated. Our results were compared with those previously published obtained through Monte Carlo simulation, ionization chambers and TLD dosimeters. The results obtained in this work allow studying the dependency of the mentioned dosimetric quantities with the half-value layer, tube voltage, anode-filter combination, field size, focusfilm distance and breasting thickness of the breast.

As simulações de escoamentos em torno de geometrias de aplicações industriais (geometrias complexas), como por exemplo configurações de aeronaves com hipersustentadores defletidos, apresentam uma vasta gama de estruturas vorticais (complexidade do escoamento). A importância das interações entre as estruturas é grande para a correta previsão da dinâmica das estruturas vorticais presentes no escoamento, uma vez que estas interações ditam as características do processo de transferência de energia cinética turbulenta. Vale ressaltar que no processo de transferência de energia cinética turbulenta não temos uma única direção e sim a possibilidade de duas direções, que representam o processo de cascata direta ou clássica (a transferência de energia cinética turbulenta se dá das maiores estruturas vorticais para as menores - forward scatter ) e a cascata indireta (a transferência de energia cinética turbulenta que se dá das menores estruturas vorticais para as maiores - backscatter ). O balanço entre estes dois processos, direto e indireto, resulta na dominância do processo direto, ou seja, o processo dominante de transferência de energia se dá das maiores estruturas vorticais para as menores. Entretanto, ambos os processos devem estar presentes na solução numérica, para que esta seja capaz de prever de forma correta a dinâmica (interações entre estruturas vorticais de tamanhos variados) presente no escoamento. Os modelos convencionais utilizados no tratamento da turbulência (ou fechamento da turbulência), sejam do tipo RANS (Reynolds Average Navier Stokes ) ou do tipo LES (Large Eddy Simulation) apresentam limitações teóricas (modelo não é capaz de representar as interações entre todas as escalas presentes no escoamento) e práticas (necessidade de discretização espacial que aumenta significativamente o custo computacional). No caso dos modelos LES a malha nas proximidades de paredes sólidas deveriam ser extremamente refinadas, o que resulta em praticamente resolver todas as escalas, para representar os efeitos da cascata direta (forward scatter ) e da cascata indireta (backscatter ) de energia cinética turbulenta. Isto ocorre em decorrência do caráter dissipativo dos modelos submalha utilizadas nas formulações LES. Por este motivo, o presente trabalho tem por objetivo desenvolver uma metodologia para solução do escoamento turbulento que seja capaz de apresentar os processos de cascata direta e cascata indireta sem a necessidade de malhas extremamente refinadas. Para tanto, iremos utilizar as equações Navier-Stokes escritas em função das flutuações (flutuações resolvidas), sendo esta formulação baseada nos trabalhos de Morris et al. [1997], Labourasse e Sagaut [2002] e Batten et al. [2004b]. As equações são obtidas por meio da divisão dos campos em uma média temporal, flutuações resolvidas e flutuações submalha. Sendo a média temporal, obtida previamente por meio de uma solução RANS do escoamento, que no nosso caso é obtida com o modelo RANS SA-QCR2013 proposto por Mani et al. [2013]. As flutuações resolvidas são o resultado da solução numérica das equações obtidas com a discretização espacial dada pela malha utilizada. Por fim as flutuações submalha são introduzidas via modelo de Billson [2004] (modelo de sintetização ou reconstrução da turbulência). Esta formulação foi aplicada para solução do escoamento em um canal formado por paredes paralelas com Re? = 395 e Re? = 1000. Estes números de Reynolds foram escolhidos por existirem resultados obtidos via DNS ou até mesmo resultados experimentais disponíveis na literatura, os resultados são enconstrados em Moser et al. [1999], del Álamo et al. [2004] e Schultz e Flack [2013]. Os resultados obtidos com o modelo proposto mostraram que a cascata inversa (backscatter ) está presente em todas as regiões da camada limite (subcamada laminar, buffer layer e logarítmica) do canal, onde o pico de transferência ocorre, para os números de Reynolds avaliados, na região da buffer layer. Este comportamento foi observado nos resultados gerados por todas as malhas avaliadas, a diferenças entre as malhas está no refinamento na região próxima às paredes sólidas. O refinamento da malha na direção da altura do canal (normal às paredes sólidas) faz com que o balanço entre as taxas de dissipação de energia cinética turbulenta passe a indicar a dominância da cascata direta no processo de transferência de energia. Nas malhas menos refinadas na região próxima à parede temos o domínio da cascata indireta no processo de transferência de energia cinética turbulenta. A introdução das flutuações submalha via modelo de sintetização da turbulência leva a uma tendência de inverter o domínio da cascata inversa (backscatter ) nas malhas menos refinadas. Os resultados obtidos com a metodologia NLDE com flutuações turbulentas submalha introduzidas por meio de modelo de sintetização turbulenta apresentam boa concordância com os respectivos resultados obtidos via DNS e ou experimentais. / Simulations of flows around industrial geometries (complex geometries), such as configurations of aircraft with deployed high-lift surface, present a wide range of vortical structures (flow complexity). The importance of the interactions between the structures is great for the correct prediction of the dynamics of the vortical structures present in the flow since these interactions dictate the characteristics of the turbulent kinetic energy transfer process. It is noteworthy that in the process of transferring turbulent kinetic energy we do not have a single direction but the possibility of two directions, which represent the direct cascade or classical cascade process (the transfer of turbulent kinetic energy occurs from the large eddy to small eddy - the forward scatter) and the reverse cascade (the transfer of turbulent kinetic energy occurs from small eddy to the large eddy - backscatter). The net balance between these two processes, direct and reverse, results in the predominance of the direct process, that is, the dominant process of energy transfer occurs from the largest eddy to the smaller ones. However, both processes must be present in a numerical solution, so that it is able to predict correctly the dynamics (interactions between vortical structures of varying sizes) present in the flow. The conventional models used in turbulence treatment (or turbulence closure), whether of the RANS (Reynolds Average Navier Stokes) type or the LES (Large Eddy Simulation) type have theoretical limitations (model is not able to represent the interactions between the scales present in the flow) and practices (needs spatial discretization that signifcantly increases the computational cost). In the case of LES models, the mesh close to solid walls should be extremely refined, which results in practically resolving all scales to represent the effects of the forward scatter and the backscatter of turbulent kinetic energy. This is due to the dissipative character of the sub-grid models used in the LES formulations. For this reason, the present research effort aims to develop a methodology for solving turbulent flow, that is able to present both energy transfer process, forward scatter and backscatter without the need of extremely refined meshes. For this, we will use the Navier-Stokes equations written in function of the fluctuations (resolved fluctuations), being this formulation based on the works of Morris et al. [1997], Labourasse e Sagaut [2002] and Batten et al. [2004b]. The equations are obtained by dividing the fields into an average time, resolved fluctuations and sub-grid fluctuations. The time-averaged, obtained previously by means of a RANS solution of the flow, which in our case is obtained with the model RANS SA-QCR2013 proposed by Mani et al. [2013]. The resolved fluctuations are the result of the numerical solution of the equations obtained with the spatial discretization given by the mesh used. Finally, the sub-grid turbulence fluctuations are introduced via the model of Billson [2004] (model for synthesizing or reconstructing turbulence). This formulation was applied to solve of the flow in a channel formed by parallel walls at Re? = 395 and Re? = 1000. The reason to choose those Reynolds number is related to the fact that there are results obtained via DNS or even experimental results available in the literature, one can found those results in Moser et al. [1999], del Álamo et al. [2004] and Schultz e Flack [2013]. The results obtained with the proposed model showed that the backscatter is present in all regions of the boundary layer (lamellar layer, buffer layer, and log-layer) of the channel, where the transfer peak occurs, for the evaluated Reynolds numbers, in the region of the buffer layer. This behavior was observed in the results generated by all meshes evaluated, the differences between the meshes are in the refinement in the region near the solid walls. The refinement of the mesh in the direction of the channel height (normal to the solid walls) causes the balance between the rates of dissipation of turbulent kinetic energy to indicate the dominance of the direct cascade in the energy transfer process. In the less refined meshes in the region near the wall, we have the domain of the indirect cascade in the process of transfer of turbulent kinetic energy. The introduction of the sub-grid fluctuations via the turbulence synthesizing model leads to a tendency to invert the reverse cascade domain (backscatter) in the solutions obtained with the coarsest grid. The results obtained with the NLDE turbulence, in which we use a synthetic turbulence model to introduce subgrid turbulent fluctuations, show good agreement with DNS results and or experimental results.

As simulações de escoamentos em torno de geometrias de aplicações industriais (geometrias complexas), como por exemplo configurações de aeronaves com hipersustentadores defletidos, apresentam uma vasta gama de estruturas vorticais (complexidade do escoamento). A importância das interações entre as estruturas é grande para a correta previsão da dinâmica das estruturas vorticais presentes no escoamento, uma vez que estas interações ditam as características do processo de transferência de energia cinética turbulenta. Vale ressaltar que no processo de transferência de energia cinética turbulenta não temos uma única direção e sim a possibilidade de duas direções, que representam o processo de cascata direta ou clássica (a transferência de energia cinética turbulenta se dá das maiores estruturas vorticais para as menores - forward scatter ) e a cascata indireta (a transferência de energia cinética turbulenta que se dá das menores estruturas vorticais para as maiores - backscatter ). O balanço entre estes dois processos, direto e indireto, resulta na dominância do processo direto, ou seja, o processo dominante de transferência de energia se dá das maiores estruturas vorticais para as menores. Entretanto, ambos os processos devem estar presentes na solução numérica, para que esta seja capaz de prever de forma correta a dinâmica (interações entre estruturas vorticais de tamanhos variados) presente no escoamento. Os modelos convencionais utilizados no tratamento da turbulência (ou fechamento da turbulência), sejam do tipo RANS (Reynolds Average Navier Stokes ) ou do tipo LES (Large Eddy Simulation) apresentam limitações teóricas (modelo não é capaz de representar as interações entre todas as escalas presentes no escoamento) e práticas (necessidade de discretização espacial que aumenta significativamente o custo computacional). No caso dos modelos LES a malha nas proximidades de paredes sólidas deveriam ser extremamente refinadas, o que resulta em praticamente resolver todas as escalas, para representar os efeitos da cascata direta (forward scatter ) e da cascata indireta (backscatter ) de energia cinética turbulenta. Isto ocorre em decorrência do caráter dissipativo dos modelos submalha utilizadas nas formulações LES. Por este motivo, o presente trabalho tem por objetivo desenvolver uma metodologia para solução do escoamento turbulento que seja capaz de apresentar os processos de cascata direta e cascata indireta sem a necessidade de malhas extremamente refinadas. Para tanto, iremos utilizar as equações Navier-Stokes escritas em função das flutuações (flutuações resolvidas), sendo esta formulação baseada nos trabalhos de Morris et al. [1997], Labourasse e Sagaut [2002] e Batten et al. [2004b]. As equações são obtidas por meio da divisão dos campos em uma média temporal, flutuações resolvidas e flutuações submalha. Sendo a média temporal, obtida previamente por meio de uma solução RANS do escoamento, que no nosso caso é obtida com o modelo RANS SA-QCR2013 proposto por Mani et al. [2013]. As flutuações resolvidas são o resultado da solução numérica das equações obtidas com a discretização espacial dada pela malha utilizada. Por fim as flutuações submalha são introduzidas via modelo de Billson [2004] (modelo de sintetização ou reconstrução da turbulência). Esta formulação foi aplicada para solução do escoamento em um canal formado por paredes paralelas com Re? = 395 e Re? = 1000. Estes números de Reynolds foram escolhidos por existirem resultados obtidos via DNS ou até mesmo resultados experimentais disponíveis na literatura, os resultados são enconstrados em Moser et al. [1999], del Álamo et al. [2004] e Schultz e Flack [2013]. Os resultados obtidos com o modelo proposto mostraram que a cascata inversa (backscatter ) está presente em todas as regiões da camada limite (subcamada laminar, buffer layer e logarítmica) do canal, onde o pico de transferência ocorre, para os números de Reynolds avaliados, na região da buffer layer. Este comportamento foi observado nos resultados gerados por todas as malhas avaliadas, a diferenças entre as malhas está no refinamento na região próxima às paredes sólidas. O refinamento da malha na direção da altura do canal (normal às paredes sólidas) faz com que o balanço entre as taxas de dissipação de energia cinética turbulenta passe a indicar a dominância da cascata direta no processo de transferência de energia. Nas malhas menos refinadas na região próxima à parede temos o domínio da cascata indireta no processo de transferência de energia cinética turbulenta. A introdução das flutuações submalha via modelo de sintetização da turbulência leva a uma tendência de inverter o domínio da cascata inversa (backscatter ) nas malhas menos refinadas. Os resultados obtidos com a metodologia NLDE com flutuações turbulentas submalha introduzidas por meio de modelo de sintetização turbulenta apresentam boa concordância com os respectivos resultados obtidos via DNS e ou experimentais. / Simulations of flows around industrial geometries (complex geometries), such as configurations of aircraft with deployed high-lift surface, present a wide range of vortical structures (flow complexity). The importance of the interactions between the structures is great for the correct prediction of the dynamics of the vortical structures present in the flow since these interactions dictate the characteristics of the turbulent kinetic energy transfer process. It is noteworthy that in the process of transferring turbulent kinetic energy we do not have a single direction but the possibility of two directions, which represent the direct cascade or classical cascade process (the transfer of turbulent kinetic energy occurs from the large eddy to small eddy - the forward scatter) and the reverse cascade (the transfer of turbulent kinetic energy occurs from small eddy to the large eddy - backscatter). The net balance between these two processes, direct and reverse, results in the predominance of the direct process, that is, the dominant process of energy transfer occurs from the largest eddy to the smaller ones. However, both processes must be present in a numerical solution, so that it is able to predict correctly the dynamics (interactions between vortical structures of varying sizes) present in the flow. The conventional models used in turbulence treatment (or turbulence closure), whether of the RANS (Reynolds Average Navier Stokes) type or the LES (Large Eddy Simulation) type have theoretical limitations (model is not able to represent the interactions between the scales present in the flow) and practices (needs spatial discretization that signifcantly increases the computational cost). In the case of LES models, the mesh close to solid walls should be extremely refined, which results in practically resolving all scales to represent the effects of the forward scatter and the backscatter of turbulent kinetic energy. This is due to the dissipative character of the sub-grid models used in the LES formulations. For this reason, the present research effort aims to develop a methodology for solving turbulent flow, that is able to present both energy transfer process, forward scatter and backscatter without the need of extremely refined meshes. For this, we will use the Navier-Stokes equations written in function of the fluctuations (resolved fluctuations), being this formulation based on the works of Morris et al. [1997], Labourasse e Sagaut [2002] and Batten et al. [2004b]. The equations are obtained by dividing the fields into an average time, resolved fluctuations and sub-grid fluctuations. The time-averaged, obtained previously by means of a RANS solution of the flow, which in our case is obtained with the model RANS SA-QCR2013 proposed by Mani et al. [2013]. The resolved fluctuations are the result of the numerical solution of the equations obtained with the spatial discretization given by the mesh used. Finally, the sub-grid turbulence fluctuations are introduced via the model of Billson [2004] (model for synthesizing or reconstructing turbulence). This formulation was applied to solve of the flow in a channel formed by parallel walls at Re? = 395 and Re? = 1000. The reason to choose those Reynolds number is related to the fact that there are results obtained via DNS or even experimental results available in the literature, one can found those results in Moser et al. [1999], del Álamo et al. [2004] and Schultz e Flack [2013]. The results obtained with the proposed model showed that the backscatter is present in all regions of the boundary layer (lamellar layer, buffer layer, and log-layer) of the channel, where the transfer peak occurs, for the evaluated Reynolds numbers, in the region of the buffer layer. This behavior was observed in the results generated by all meshes evaluated, the differences between the meshes are in the refinement in the region near the solid walls. The refinement of the mesh in the direction of the channel height (normal to the solid walls) causes the balance between the rates of dissipation of turbulent kinetic energy to indicate the dominance of the direct cascade in the energy transfer process. In the less refined meshes in the region near the wall, we have the domain of the indirect cascade in the process of transfer of turbulent kinetic energy. The introduction of the sub-grid fluctuations via the turbulence synthesizing model leads to a tendency to invert the reverse cascade domain (backscatter) in the solutions obtained with the coarsest grid. The results obtained with the NLDE turbulence, in which we use a synthetic turbulence model to introduce subgrid turbulent fluctuations, show good agreement with DNS results and or experimental results.

Ophiolites - thrust sheets of oceanic lithosphere that have been emplaced onto the continental margin - provide the opportunity to explore the structure and genesis of oceanic crust. As many ophiolites formed above subduction zones, they also allow for the investigation of mantle wedge and subduction interface processes. This the- sis examines the Oman-United Arab Emirates (UAE) ophiolite, which is the largest and most intensely studied ophiolite on Earth. Three distinct problems are addressed. (1) Recent research has proposed that the architecture and tectonic evolution of the ophiolite in the UAE differs from in Oman. In Chapter 2, I test this hypothesis by integrating new geological mapping and field observations with previously published maps of the ophiolite in the UAE. My results indicate that the ophiolite is gently folded, but otherwise largely intact. I demonstrate that the architecture of the ophi- olite in the UAE is not significantly different from in Oman. Thus, there is no basis for a different tectonic evolution as recently proposed. (2) Observations from exper- iments and small-scale natural shear zones indicate that volumetrically-minor phases can control strain localization. In Chapter 3, I test the hypothesis that minor phases control strain-localisation at plate boundaries. To do so, I analyzed peridotites from the base of the ophiolite, a palaeosubduction interface. My results demonstrate that minor phases limited olivine grain growth, which led to rheological weakening. (3) The mechanisms by which metamorphic soles detached from the downgoing slab and accreted to the hanging-wall mantle is unclear. In Chapter 4, I examine a transect across the metamorphic sole in the UAE. My results reveal that granulite formation was more extensive than is typically considered. I propose that granulite formation resulted in rheological strengthening, which caused the subduction interface to migrate into the downgoing slab and accrete the metamorphic sole.