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Orientadores: Dirceu Noriler, Henry França Meier Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: Trocadores de calor tipo casco e tubos (TCCT) são equipamentos largamente utilizados nas indústrias em geral, como é o caso do processo de hidrotratamento (HDT) na indústria do refino de petróleo (Longhi et al. (2012)), como a hidrogenação catalítica de cargas que darão origem aos combustíveis. Em alguns casos, como o HDT, há a mistura direta das fases líquida e gasosa/vapor e esta mistura precisa ser aquecida ou resfriada em um trocador de calor. Alguns autores têm mostrado que quando esta mistura bifásica está em trocadores de calor com escoamento vertical (Grant; Chisholm (1979)), ou feixe de tubos (Kanizawa; Ribatski (2017a)), podem ocorrer no interior destes equipamentos diversos padrões de escoamento como: estratificado, bolhas, spray ou intermitente. O presente trabalho tem como objetivo estudar e quantificar as oscilações de pressão em trocador de calor tipo casco e tubos, com escoamento predominantemente horizontal, causadas pelo regime de fluxo intermitente. Os dados foram adquiridos com sensores de pressão em seis pontos no equipamento experimental a frio com ar e água (25 °C), com a finalidade de acompanhar a golfada de líquido (slug flow) que ocorre no trocador de calor, e também com sensores de massa, sendo quatro células de carga instaladas na base do equipamento. Foi realizado planejamento experimental completo com 52, sendo 5 níveis para cada uma das 2 variáveis (velocidade do ar e da água), sendo mapeadas 25 condições experimentais. As velocidades avaliadas foram: 0 m/s; 0,25 m/s; 0,50 m/s; 0,75 m/s e 1 m/s para o ar e 0 m/s; 0,025 m/s; 0,050 m/s; 0,075 m/s e 0,1 m/s para a água. Os dados de pressão coletos foram filtrados e analisados os valores máximos, mínimos e de diferencial de pressão, além do desvio padrão da pressão atingida em cada um dos casos. Além disso, a massa total do sistema também foi avaliada, sendo essas comparações em relação às velocidades superficiais do ar e da água. Para o filtro, os dados foram separados via transformada wavelet e reagrupados por Multy-Resolution Analysis (MRA) em 3 níveis de sinais, micro escala, mesoescala e macroescala, que foram utilizados para filtrar os dados que continham ruído de alta frequência, sendo utilizados os dados da macroescala para as análises estatísticas. Após o entendimento dos fenômenos que ocorriam na geometria padrão, foram propostas por simulação numérica (CFD), em geometria simplificada, alternativas para mitigação do slug. Foi selecionado o caso que apresentou melhor desempenho, sendo este testado e comparado com os resultados da geometria original. A proposição geométrica proporcionou diminuição das oscilações de vazão e de pressão em todos os experimentos bifásicos analisados, não havendo mais golfadas em nenhum dos casos. Os valores de pressão média para os casos avaliados não apresentaram alterações significativas, enquanto, o desvio padrão da pressão diminuiu consideravelmente. A média da massa apresentou pequena diminuição para a geometria proposta, o que reflete em uma menor quantidade de água dentro do equipamento Abstract: Shell and tube heat exchangers are equipment widely used in industries in general, as is the case of the hydrotreating process (HDT) in the oil refining industry (Longhi et al. (2012)). In some cases, such as HDT, there is a direct mixture of the liquid and gas/vapor phases and this mixture needs to be heated or cooled in a heat exchanger. Some authors have shown that when this two-phase mixture is in vertical-flow heat exchangers (Grant; Chisholm (1979) or tube bundles (Kanizawa; Ribatski (2017a)), several flow regimes can occur inside these equipment such as: stratified, bubbles, spray or intermittent. The present work aims to study and quantify the pressure fluctuations in shell and tube heat exchanger, with predominantly horizontal flow, caused by the intermittent flow regime. The pressure data were acquired with sensors in six points of the experimental facility with air and water (25 °C), to monitor the slug flow that occurs in the heat exchanger, and also with mass sensors, with four load cells being added to the base of the equipment. The experimental conditions were carried out based in a design of experiments with 52 (5 levels for 2 phase), the 25 experimental conditions were mapped. The evaluated superficial velocity were: 0 m/s; 0.25 m/s; 0.50 m/s; 0.75 m/s and 1 m/s for air and 0 m/s; 0.025 m/s; 0.050 m/s; 0.075 m/s and 0.1 m/s for water. The collected pressure data were filtered and the values of maximum, minimum, differential of pressure and standard deviation of the pressure reached in each case were analyzed, in addition, the total mass of the system was also evaluated, these comparisons being in relation to the surface velocities of air and water. For the filter, the data were separated via a wavelet transform and regrouped by Multy-Resolution Analysis (MRA) in 3 levels of signals, microscale, mesoscale, and macroscale, which were used to filter the data that contained high-frequency noise, being used macroscale data for statistical analysis. After understanding the phenomena that occurred in standard geometry, some alternatives for mitigating the slug flow were proposed by numerical simulation (CFD), in simplified geometry. The geometric proposition provided a significant decrease in flow and pressure oscillations and in all the two-phase experiments analyzed. There is no more slug flow in either case. The mean pressure values for the evaluated cases did not show significant changes, while the standard deviation of the pressure decreased considerably. The mass average showed a small decrease for the proposed geometry, which reflects in a smaller amount of water inside the equipment Doutorado Engenharia Química Doutor em Engenharia Química PETROBRAS 5850.0103010.16.9

Debi süreklilik çizgisi, akarsu akımlarının değerlendirilmesinde yaygın bir şekilde kullanılmaktadır. Debi süreklilik çizgisi; taşkın kontrolü, düşük akım ve kuraklık çalışmaları, su kaynakları ve hidroelektrik santralların planlanması ve işletilmesi, yağmur suyu drenaj sistemlerinin tasarımı gibi birçok hidrolojik çalışmada kullanılmaktadır. Ayrıca hidrolojik havzalarda akım tahmini ve eksik akım verilerinin tamamlanması gibi konularda debi süreklilik çizgisinden yararlanılmaktadır.Debi süreklilik çizgisi kullanılarak akarsudaki taşkın veya düşük akım gibi uç debiler ile yıllık ortalama akım belirlenebilmektedir. Ancak her havzada yeterli uzunlukta gözlem olmadığından ve hatta bazı havzalarda hiç gözlem bulunmadığından havzanın meteorolojik, topografik ve morfolojik karakteristikleri yardımıyla debi süreklilik çizgisi elde edilebilir. Debi süreklilik çizgisi ile ilgili modeller, matematiksel, istatistiksel, stokastik, grafik ve diğer modeller şeklinde sınıflandırılabilir. Ayrıca yıllık, aylık ve günlük akımlar kullanılarak debi süreklilik çizgisi elde edilebilir. Seçilecek zaman aralığı çalışmanın amacıyla ilişkilidir.Bu çalışma akım ölçümü olmayan kuruyan akarsularda debi süreklilik çizgisi ile ilgilidir. Akarsularda kuruma oranı zaman aralığı küçüldükçe artmaktadır. Yani aynı bir akarsuda yıllık ve hatta aylık zaman ölçeğinde sürekli akan bir akarsu günlük zaman ölçeğinde kuruyan akarsu niteliği taşıyabilir.Bu çalışmada geliştirilen debi süreklilik çizgisi modeli boyutsuzlaştırma, normalleştirme, kuruma noktası, normal kuantillerin hesabı, boyutsuz kuantillerin ters dönüşümü, ortalama debi ve boyutlu kuantillerin hesabı adımlarından oluşmaktadır. Kuruma noktası, kuruyan bir akarsuda debi süreklilik çizgisinin yatay ekseni kestiği aşılma yüzdesini ifade etmektedir. Kuruma noktası ve ortalama debi tahmininde havza karakteristiklerinden yararlanılmıştır. Model ile elde edilen debi süreklilik çizgileri değerlendirme ölçütleri kullanılarak incelenmiştir. Havza karakteristiklerinin hesabında hidrolojik çalışmalarda ve taşkın alanlarının belirlenmesinde MERIT DEM verisi ile çalışılmıştır. Bu veri sayesinde coğrafi bilgi sistemleri yazılımında havza karakteristikleri ve havzanın alansal yağışı hesaplanmıştır.Uygulamada Seyhan, Ceyhan, Meriç ve Gediz havzalarından seçilen ve olabildiğince insan müdahalesinden uzak Akım Gözlem İstasyonları (AGİ) seçilmiştir. Müdahaleli AGİ'lerde yeteri kadar uzun olması koşuluyla müdahele öncesi veriler değerlendirmeye alınmıştır.Yıllık debi süreklilik çizgisi uygulaması için Seyhan ve Ceyhan havzaları üzerinde gerçekleştirilmiştir. Çalışmanın konusu olan kuruyan akarsular ele alındığında Seyhan havzasından seçilen AGİ'lerin günlük zaman ölçeğinde bile kurumadığı belirlenmiş, bu nedenle aylık debi süreklilik çizgisi uygulamasına Ceyhan havzası ile devam edilmiştir. Günlük debi süreklilik çizgisi uygulamasında ise Ceyhan havzasının yanı sıra Meriç ve Gediz havzaları da kullanılmıştır. Ortalama debi tahmininde sonuçlar kabul edilebilir mertebededir. Benzer şekilde kuruma noktası hesabında da başarılı sonuçlar elde edilmiştir. Model sonuçlarının değerlendirilmesinde determinasyon katsayısı, ortalama karesel hatanın karekökü, ortalama mutlak hata gibi değerlendirme ölçütleri kullanılmıştır. Bunun yanında debi süreklilik çizgisini yüksek, orta ve düşük akımlar olarak üç parçaya ayırarak değerlendiren değerlendirme ölçütlerinden de yararlanılmıştır. Debi süreklilik çizgisi güven aralıkları, her bir gözlem yılına ait debi süreklilik çizgileri yardımıyla belirlenmiştir.Kuruyan akarsuların debi süreklilik çizgisi nispeten çok yeni olup çalışmalar genellikle belli bir aşılma yüzdesindeki debi değerini tahmin etmeye dayanmaktadır. Akım ölçümü olmayan havzalarda kuruyan bir akarsuyun debi süreklilik çizgisinin kuruma noktası yağış ve havza karakteristiklerine bağlı bir regresyon denklemi ile hesaplanmıştır. Günümüz coğrafi bilgi sistemleri ve uydu teknolojisi sayesinde hesaplanabilen havza karakteristikleri ile akım ölçümü olmayan kuruyan akarsularda debi süreklilik çizgisinin elde edilmesi, böylelikle bu akarsuların su potansiyellerinin en iyi şekilde değerlendirilmesi gelecekte mümkün görülmektedir. A flow duration curve is used to determine the discharge of a certain time percentage (quantile) in hydrological basins. It can simply be obtained by sorting the observed streamflow time series in the ascending order and plotting it against its corresponding duration. In a gauged basin, it is obtained by sorting the observed flow from the largest to the smallest, and plotting against the corresponding exceedance probability. At ungauged basins where no data exists the need for developing empirical methods emerges. Flow duration curves are useful tools for characterizing hydrological regimes and flow variability. They are widely used in the determination of the upper extreme events (floods) as well as in the calculation of low-flow characteristics of streams. The urban storm water modelling, environmental flow allocation and the determination of hydropower potential and water availability at ungauged sites are all performed by using flow duration curves.Flow duration curve-related studies started as early as the first half of the 20th century for producing weekly flow duration curves. Due to the importance of water resources, flow duration curves have always been studied in the water-related development and planning projects for which extensive hydrological engineering practice is needed. Therefore, there are quite high number of studies in the literature based on a wide range of methodologies such as regression equations, probabilistic and empirical approaches, analytical and statistical methods, and soft computational techniques applied at individual gauging stations or used at regional scale. Flow duration curve models were established using regression equations based on morphological characteristics such as drainage area and elevation of the hydrological basin. Flow duration curve at ungauged basins were estimated by regression equations between the mean flow and the drainage area, and precipitation over the hydrological basin.Probability distribution functions have also widely been used in the flow duration curve literature as well as the analytical and statistical methods. Recently, soft computational techniques such as artificial neural networks, gene expression programming and geostatistical methods have also been applicable extensively in the flow duration curve literature.Not all hydrological basins are properly gauged. Therefore, regional flow duration curves have been studied for many cases aiming at transferring information at gauged sites to ungauged sites. In regional flow duration curves, morphological characteristics of the hydrological basin are used solely or they are combined with the parameter of the probability distribution function. For the ungauged basins, regression equations using the drainage area as an input has always been valuable. Methodologies used for the flow duration curves of ungauged basins consider also the dominant landscape and climate characteristics and also the karstic and non-karstic structure of the hydrological basin. A regional model for the estimation of the dimensionless flow duration curve in sites with no or limited data has a higher importance due to the generalization ability of the dimensionless flow duration curve.This study aims at developing flow duration curve models for ungauged basins. Flow duration curves are obtained at annual, monthly and daily time scales.The flow duration curve models are based on empirical regression equations between the annual mean flow and the hydrological basin characteristics such as precipitation, slope, basin relief, basin area and drainage density. Steps of the method proposed for the flow duration curve of ungauged intermittent river basins are composed of following steps:•Nondimensionalization: Annual mean flow time series of each gauging station is nondimensionalized by dividing with the long-term mean streamflow of the gauging station.•Normalization: The dimensionless annual mean flow is transformed to fit normal distribution using a proper transformation.•Calculation of cease-to-flow proportion: An empirical model is proposed which accommodates the drainage area of basin, annual precipitation, basin relief, topographical slope, and the drainage density. This step exists only in the daily flow duration curve model. •Calculation of the normalized quantiles: The mean value and standard deviation of the normalized streamflow time series are calculated.•Back transformation of the dimensionless quantiles: For the known transformed quantiles, any quantile of a given exceedance probability can be derived by inverse transformation.•Calculation of annual mean flow: An empirical model is proposed, which accommodates the drainage area of the basin, annual precipitation, basin relief, topographical slope and the drainage density to calculate the annual, monthly and daily mean flow of each hydrological basin. Log-linear regression equations are preferred.•Calculation of dimensional quantiles: Discharge at any exceedance probability for an ungauged basin is calculated by multiplying the transformed dimensionless quantile with the empirically calculated mean value of the discharge from the hydrological basin.Four river basins were used for the case studies which are Seyhan and Ceyhan river basins in the Mediterranean region, Gediz river basin in the Aegean region and Meriç river basin in Thrace. Seyhan and Ceyhan river basins are considered for the annual flow duration curve model while the Seyhan river basin has been excluded in the monthly flow duration curve model for which the Ceyhan river basin is used solely. Finally, for the daily flow duration curve model, Gediz and Meriç river basins were taken for the application of the model.Data from the Seyhan and Ceyhan river basins are used for the annual flow duration curve model. In total, 109 gauging stations were used, 20 of which were selected for the validation of the model while the remaining 89 were used for the calibration. At monthly time scale, data from 42 gauging stations in the Ceyhan river basin are considered. When the daily time step is considered for the model, number of gauging stations has increased to 48. In total, 1792 station-year annual flow data were used for the modelling; 1452 station-years for calibration and 340 station-years for validation. The total number of data has increased to 13944 station-month and 407340 station-day, for the monthly and daily time steps, respectively. It should be emphasized that gauging stations on the tributaries not on the main river are studied with the sake of limiting anthropogenic activities on the rivers.The developed models were evaluated at the annual, monthly and daily time steps. Evaluation of the models were checked by the performance criteria such as determination coefficient, root mean square error and mean absolute error. However, due to the great variability between the higher and lower ends of the flow duration curves, it has not been possible to apply one single performance metric to the whole flow duration curve. Therefore, performance metrics called BiasFLV and BiasFHV were also used to check the models.At annual scale, the dimensionless flow duration curve obtained from the model was fitted to the observation at the calibration and validation stages appropriately. A regression equation was established between the mean flow of the basin and the product of the basin area and precipitation as one single variable. The equation estimated quite well the mean flow for all basins. The annual flow duration curves were mainly found proper for the basins. However, the annual flow duration curve estimated higher flow in a couple of basins with lower flow.Owing to the aim of the study that intermittent rivers are interested, Seyhan River basin was excluded as this particular basin has no intermittent flow at all at monthly time scale. The same methodology as the annual flow duration curve model was applied. The regression between the mean flow of the basin was constructed again with the product of the basin area and precipitation as one single variable. Results show a very good performance between the observed and estimated mean flows of the rivers. As for the flow duration curves, it was observed that higher and middle segments of the flow duration curve were fitted quite good. However, the lower segment of the flow duration curve is usually overestimated.At the daily scale, only intermittent rivers of the Ceyhan, Meriç and Gediz river basins were used. Flow duration curves of intermittent rivers take into account also the cease-to-flow point which was formulated as a regression model considering the basin area, precipitation, basin relief, slope, and drainage density as independent variables. Better results were obtained for the estimated mean flow values compared to the mean flow at the annual and monthly time scales. Results in terms of flow duration curves are particularly good in river basins with higher intermittency.A flow duration curve model is presented in this study at annual, monthly and daily time scales as an effort to make a contribution to the existing flow duration curve literature. The model accommodates an empirical regression model that counts not only on the drainage area of the hydrological basin as usual but also precipitation, slope, basin relief and drainage density as additional independent variables to calculate the annual mean flow. Although the model may have a low performance in some particular stations deviating from the average hydrological behavior of the basin, higher performance might be expected with empirical models better approaching the observed mean flow. This is the key issue of the flow duration curve development methodology to be further analyzed. Results of the application are finally found such promising that the model can be considered a good foundation for the development of flow duration curves at ungauged intermittent river basins at annual and shorter time intervals such as monthly and daily. 164

Passive acoustic monitoring has revolutionized the characterization of industrial processes and the acoustic wavefield in various environments. However, cryospheric acoustic phenomena remain largely unknown, especially at medium and small scales. Furthermore, the englacial drainage system is poorly documented, even though it is fundamental for understanding water routing through the glacier body. Here I present the first-of-its-kind in situ records of periodic or sustained acoustic signals generated by water drainage through crevasses at the calving front of a glacier, in this case a Greenlandic tidewater glacier. The generative mechanisms of gurgling and bubbling noise are explained as flow-induced sounds that are excited by intermittent air-water two-phase flow and Helmholtz resonance, respectively. This paper demonstrates that there is the tremendous potential to study near-surface glacier systems using acoustic methods and detect different flow patterns in englacial conduits from their acoustic signatures, both of which can significantly advance our understanding of glaciological processes. Plain Language Summary The glacier surface is full of various audible sounds. While early polar explorers have documented this noisy glacier environment, these qualitative observations have never been supported by measurements. For example, Nansen (1897), wrote, "I can hear reports from the glacier... whenever it turns cold-it writhes horribly, and crevice after crevice appears in the huge body; there is a noise like the discharge of guns, and the sky and the earth tremble so that I can feel the ground that I am lying on quake" while wintering in Franz Josef Land, and Baldwin (1896) described his crossing of Bowdoin Glacier, which is the subject of this study, as follows: "...shrieking sounds frightful enough, came...to our ears, seeming to vibrate through...our very bodies, spitefully shouting in our ears: Why, presumptuous man, hast thou set disturbing foot upon my chaste bosom?" Here I analyze the first acoustic records that were directly acquired on a glacier, in Greenland, which reveal previously unknown repetitive or continuous sound sources. It appears that different patterns in air-water interactions give rise to interesting acoustic phenomena, such as bubble resonance and unstable flow in cracks. Future glaciological investigations could consider using microphones to better understand englacial water drainage.

International audience; An optical method is developed for a 2.95 mm inner diameter circular mini-channel to estimate liquid film thicknesses. The greyscale pictures obtained with a high-speed camera are processed to determine the liquid-vapour interface positions for annular and intermittent flows. The experiments are thus performed for a large range of flow conditions. The saturation temperatures tested ranged from 20°C to 100°C in steps of 10°C and the mass velocities are 50, 100, 200, 300 and 400 kg m−2 s−1. A new parameter ranging from 0 to 1, the symmetry, is defined to account for the level of non uniformity of liquid distribution around the tube perimeter. New experimental data are presented (270 data points), that cover a range of symmetry parameter from 0.35 to 1.00. These data are merged with those available in the literature (406 data points with symmetry parameter from 0.71 to 1.00). A sensitivity analysis of the dimensionless numbers of major influence is run and a new correlation is proposed, that enables to predict over 90% of the data points in an error bandwidth of 10%. This correlation is proposed as criterion for asymmetry.

Bioretention systems have been recommended as one of the best management practices for low impact development for water recycling/reuse systems. Although improvement of the stormwater quality has been reported regarding pollutants eliminations such as suspended solids and heavy metals, a substantial removal of indicator bacteria is required for possible non-potable reuse. This study investigated the efficiency of wood biochar with H2SO4-, H3PO4-, KOH-, and amino-modifications for E. coli removal from synthetic stormwater under intermittent flow. The H2SO4-modified biochar showed a specific surface area of 234.7 m(2) g(-1) (approximately double the area of original biochar), whereas a substantial reduction in surface area was found with amino-modified biochar. The E. coli removal (initial concentration of 0.3-3.2 × 10(6) CFU mL(-1)) by modified biochars as filter media was very promising with, for example, over 98% removal efficiency in the first 20 pore volumes of stormwater infiltration and over 92% removal by the end of the second infiltration cycle. Only a small portion of E. coli attached on the modified biochars (

7 páginas, 3 figuras, Stream microbial communities and associated processes are influenced by environmental fluctuations that may ultimately dictate nutrient export. Discharge fluctuations caused by intermittent stream flow are increasing worldwide in response to global change. We examined the impact of flow cessation and drying on in-stream nitrogen cycling. We determined archaeal (AOA) and bacterial ammonia oxidizer (AOB) abundance and ammonia oxidation activity in surface and deep sediments from different sites along the Fuirosos stream (Spain) subjected to contrasting hydrological conditions (i.e., running water, isolated pools, and dry streambeds). AOA were more abundant than AOB, with no major changes across hydrological conditions or sediment layers. However, ammonia oxidation activity and sediment nitrate content increased with the degree of stream drying, especially in surface sediments. Upscaling of our results shows that ammonia oxidation in dry streambeds can contribute considerably (~50%) to the high nitrate export typically observed in intermittent streams during first-flush events following flow reconnection. Our study illustrates how the dry channels of intermittent streams can be potential hotspots of ammonia oxidation. Consequently, shifts in the duration, spatial extent and severity of intermittent flow can play a decisive role in shaping nitrogen cycling and export along fluvial networks in response to global change., This research was granted by the projects DARKNESS (CGL2012-32747, MINECO) to E. O. Casamayor and MED_FORESTREAM (CGL2011-30590- CO2- 02, MINECO) and REFRESH (244121 FP7 EU Commission) to E. Martí.

Orientador: Eugênio Spanó Rosa Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica Resumo: Este trabalho propõe um solver de Riemann do tipo Roe aplicado à sistemas bifásicos gás-líquido em regime transitório empregando-se o modelo de mistura (drift-flux). Para tanto, iniciou-se o desenvolvimento deste a partir de um solver mais simples capaz de simular problemas de acústica. Num segundo estágio adaptou-se o solver para a resolução de três equações não lineares das leis de conservação em sistemas monofásicos utilizando-se gás ideal. Por fim o solver foi direcionado à resolução de sistemas gás-líquido, fazendo-se uso da linearização proposta por Roe (1981), assim como ocorrera na segunda etapa. Em todos os estágios validou-se o solver contra dados experimentais e/ou analíticos disponíveis na literatura, tais como problemas de tubo de choque e de escoamentos monofásicos e bifásicos no interior de dutos. Três principais contribuições foram apresentadas no que tange a sistemas bifásicos gás-líquido. A primeira consta da obtenção da matriz Jacobiana na sua forma exata de maneira analítica. Como os termos da matriz Jacobiana exata são bastante complexos, propôs-se uma simplificação baseada no fato de o quadrado da razão das velocidades do som nas fases gás e líquido ser muito menor que a unidade, sendo possível fornecer assim expressões algébricas mais simples para os autovalores da matriz Jacobiana. Tal hipótese simplificadora foi avaliada dentro de uma faixa de interesse prático. No processo de linearização propôs-se o uso de um vetor parâmetros de Roe ainda não testado com sucesso na literatura. Para os termos da matriz de Roe em que não foi possível uma integração totalmente analítica, aplicou-se uma quadratura gaussiana com três pontos. Diferentes esquemas de discretização foram testados na validação do solver. A priori, na etapa de validação do escoamento compressível de um gás ideal testou-se o esquema Upwind de primeira ordem, Lax-Wendroff de segunda ordem e os esquemas de alta resolução Lax-Wendroff juntamente do limitador de van Leer e Lax-Wendroff+SUPERBEE, dentre os quais, escolheu-se os esquemas de maior acurácia e que apresentaram menor custo computacional, para as simulações posteriores. Nestas, como resultados apresentou-se o comportamento transiente das variáveis de interesse em pontos específicos da tubulação. Em alguns casos o perfil destas ao longo do duto fora explorado, assim como as velocidades das ondas de pressão e de fração de vazio. Nas simulações computacionais abordou-se os padrões de escoamento de golfadas, estratificado liso/ondulado, agitado (churn), anular e de bolhas, empregando-se diferentes correlações de drift e relações de viscosidade de mistura, nos arranjos horizontal e vertical Abstract: The present thesis proposes a Roe-type Riemann solver applied to the transient gas-liquid two-phase systems employing the drift-flux model. For this, the development started from a simpler solver able to simulate acoustic problems. In a second stage the solver was adapted to solve three non-linear equations of the conservation laws in single-phase systems using an ideal gas. Finally, the proposed solver was directed to the resolution of gas-liquid flows, making use of the Roe (1981) linearization, as occurred on the second stage. At all steps the Riemann solver was validated against experimental data and/or analytical solutions avaliable in the literature, such as shock tube problems, single and two phase flow inside ducts. Three main contributions were presented regarding to the gas-liquid two-phase systems. First, the Jacobian matrix was obtained in its exact form fully analytical. As the exact Jacobian terms are extensive complex, we propose a simplification hypothesis based on the fact that the square of the ratio of the sound speeds in the gas and liquid phases is much lower than one, providing simpler algebraic expressions for the eigenvalues. The simplification hypothesis was evaluated within a range of practical interest. On the linearization process we propose a Roe parameter vector untested in the literature yet. Some terms of the Roe matrix were treated numerically using a Gauss-Legendre quadrature with three points. Different discretization schemes were tested to validate the transient solver. Initially, in the validation step of compressible flow of an ideal gas was tested the 1st order Upwind scheme, the 2nd order Lax-Wendroff, and the high resolution methods Lax-Wendroff+van Leer limiter and Lax-Wendroff+SUPERBEE limiter, among which were chosen in the further simulations the schemes that presented the highest accuracy and lower computational cost (CPU time). The results presented the transient behavior of some primitive variables of practical interest at specific points of the pipe. In some cases, the profiles were displayed along the duct for different times. The wave speeds of pressure and void fraction were also analyzed. In the computer simulations were addressed the slug, stratified smooth/wavy, churn, annular and bubbles flow patterns, by employing different drift correlations and mixture viscosity relations in horizontal and vertical arrangements Doutorado Térmica e Fluídos Doutor em Engenharia Mecânica Funcamp 4721

Velocity measurement of an intermittent high-speed flow inside a micro wave rotor cell was carried out by utilizing a laser Doppler anemometry (LDA). The cell is 3×3mm rectangular tube, whose length is 42mm. The pressure ratio and rotor speed of the wave rotor were set at 2.5 and 5000rpm, respectively. Ethanol droplets were seeded into the flow as scattering particles. By use of laser beam expanders, the beam intersection volume of the LDA optics was minimized, and submillimeter spatial resolution is realized while a wide velocity range (-100 to 300m/s) is kept. It is shown that the velocity histories at local positions inside the wave rotor cell can be obtained with the LDA optics. The rapid velocity increase and decrease, due to the primary and secondary shock waves, are observed, and the propagation speed of the primary shock wave was estimated. It is shown that the spatial distribution of the maximum velocity inside the cell is constant, and that the boundary layer thickness inside the cell is smaller than 0.5mm. It is shown that the effect of viscosity is relatively small in such a micro wave rotor.

中国雲南省の蒋家溝を対象に, 粘性土石流のメカニズムと土石流対策に関する観測調査を行って, 土石流が降雨の発生時刻からかなり遅れて発生すること。土石流が, 多数のサージが間欠的に流下するという一連のイベントからなっていて, その間欠性は, 降伏応力を用いたモデル, 天然ダムの決壊モデル, 流れの不安定性に基づくモデルを用いて説明が試みられていること。砂礫の濃度が著しく大きいにもかかわらず, 土石流が流れ易いこと。流動中の土石流には栓流が存在しないこと。さらに, 蒋家溝の中下流域での, 土石流発生に伴う地形変化が災害発生ポテンシャルを高めていること。禿げ山化した山地の緑化が進められた結果, 土石流発生などの土砂流出抑制効果が認められたが, そのメカニズムの検討が課題であることを述べた。, The observational study on the viscous debris flows at Jiang-jia Creek in Yunnan Province, China clarified the following points. The time delay of one to five hours from the beginning of rainfall to the onset of debris flow may be ascribed to an accumulating process of slurry from tributary gullies to the main channel bottom at the source reach of the debris flow. The intermittence of debris-flow surge may be explained through the mechanism either of or a complex of an yield strength model, a model of a series of breaching of small natural dams, or a model of an instability of the flow itself. The absence of plug-flow phenomena in the viscous debris flow indicates the yield strength of the flow is unexpectedly small, and a new alternative model is necessary to explain the mechanism of viscous debris flow. The field survey of the countermeasures against debris flows in Dongchuan County over five years showed the tree-planting project at mountain slopes in these several years may have been effective in increasing the slope stability, suppressing sediment discharge and debris flows. Further study is needed to evaluate this effect of countermeasure quantitatively.

Orientador: Sérgio Nascimento Bordalo Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências Resumo: Apesar dos avanços alcançados, alguns aspectos da operação do gas-lift intermitente (GLI) convencional permanecem inexplorados ou pouco estudados até o presente, como por exemplo, a concomitância de etapas do ciclo apresentada por Carvalho (2004), ou a estabilidade de ciclos em função da temporização da válvula motora e do ajuste da válvula operadora. Ao mesmo tempo, o bombeio pneumático de Zadson (BPZ) tem apresentado bons resultados em sua aplicação em campos no Brasil, motivando-se estudos para se desenvolverem simuladores computacionais para o projeto e análise destes sistemas. Neste trabalho, foi construído um simulador físico para os métodos GLI convencional e BPZ, para validar simuladores numéricos propostos anteriormente por outros autores. O aparato laboratorial é constituído por quatro conjuntos operacionais: o primeiro conjunto representa a coluna de produção do GLI convencional, o segundo conjunto representa a coluna do BPZ, o terceiro conjunto representa o acoplamento poço-reservatório e o quarto conjunto representa a injeção de gás comprimido. Para a medição, há transdutores de pressão localizados em vários pontos do aparato e tanques de medição do volume produzido. O sistema de aquisição de dados e atuação das válvulas operadora e motora é operado por uma placa micro-controlada. Testes foram realizados alterando-se as variáveis operacionais dos métodos. Como conclusões do trabalho foram identificadas a concomitância das etapas do ciclo GLI, avaliado o fallback para várias condições operacionais, estudada a estabilidade dos ciclos de GLI, e desenhado um mapa operacional das condições de um ciclo GLI regular. Além disso, foi testado o funcionamento de três modos de operação do BPZ Abstract: Despite the advances achieved so far, some important aspects of the operation of the conventional intermittent gas-lift (IGL) remain unexplored or poorly studied, as for instance, the concurrency of cycle stages, as presented by Carvalho (2004), or the stability of cycles due to motor valve timing and adjustment of the gas-lift valve. At the same time, the Zadson pneumatic pump (ZPP) has presented good results in Brazilian fields, motivating studies to develop computational simulators for the design of this method. In the course of the present work, a physical simulator was built for the IGL and ZPP, to validate numerical simulators proposed by previous authors. The laboratory apparatus consists of four operational sets; the first set is the production column of conventional IGL, the second set is the column of ZPP, the third set represents the well-reservoir coupling and the fourth set is the injection of compressed gas. For measurement, there are pressure transducers located at various points of the apparatus and tanks for measuring the produced volume. The system of data acquisition and actuation of gas-lift and motor valves are operated by a microcontroller board. Tests were performed by changing the operating variables of the gas lift methods. The results of the study are: the identification of the concurrent stages during the IGL cycle, the fallback for various operating conditions, the stability of IGL cycles, and an operating map for the conditions of a stable IGL cycle. In addition, the operation of three lifting modes of the ZPP were tested Mestrado Explotação Mestre em Ciências e Engenharia de Petróleo

We study the rheological properties of colloidal microphases in two dimensions simulating a model of colloidal particles with competing interactions. Due to the competition between short-range attraction and long-range repulsion, as a function of the density the model exhibits a variety of microphases such as clusters, stripes or crystals with bubbles. We prepare the system in a confined microphase employing Monte-Carlo simulations and then quench the system at T=0. The resulting configurations are then sheared by applying a drag force profile. We integrate numerically the equation of motion for the particles and analyze the dynamics as a function of the density and the applied strain rate. We measure the stress-strain curves and characterize the yielding of the colloidal microphases. The results depend on the type of microphase: (i) clusters are easily sheared along layers and the relative motion is assisted by rotations. (ii) Stripes shear easily when they are parallel to the flow and tend to jam when are perpendicular to it. Under a sufficiently strong shear rate perpendicular stripes orient in the flow direction. (iii) Crystals with bubbles yield by fracturing along the bubbles and eventually forming stripes. We discuss the role of dislocations, emitted by the bubbles, in the yielding process., Submitted to Phys. Rev. E. Animations of the shear of the microphases can be found at http://pil.phys.uniroma1.it/~zapperi/Supplementaryanimations.html

Gas entering the pump is one of the most common causes of decreased efficiency in a sucker rod pumped well or any pumping system. A way to combat this problem is the installation of a down-hole gas separator, also known as a gas anchor at the bottom of the pump. Unfortunately inefficient gas anchors are common and an acceptable guide for optimum gas anchor design does not exist. A gas anchor is composed of an outer barrel (known as the mud anchor) and an inner small diameter tube (known as the dip tube) that is connected to the pump inlet. The produced liquid and some of the gas enter the separator through entry ports on the mud anchor. Inside the separator the produced liquid flows down to the dip tube suction. The gas bubbles in the separator, depending on their size, either flow up and leave through vent holes or flow down into the dip tube suction. Four different gas anchor designs were tested in a laboratory well at the University of Texas production engineering facility. Three of the gas anchor designs are gravity driven gas separators (where gravity separates the gas from the liquid), and thefourth design is a static centrifugal gas separator named the Twister (where centrifugal forces separate the gas from the liquid). Testing was conducted in continuous flow, as that corresponding to a progressing cavity pumped well, and in intermittent flow, as in a sucker rod pumped well.Intermittent flow was obtained by opening and closing an automated valve. The intermittent flow conditions during testing simulated a pumping speed of 10 strokes per minute. The effect of four variables: separator entry port geometry, annular space inside the separator, liquid production rate, and gas rate entering the well, were analyzed. Previous laboratory studies7, 9 undertaken within this project confirm that when the pump inlet is below the perforations all the gas will be separated in the casing and no gas anchor is needed. Also if the gas anchor inlets are in front of the perforations theseparation efficiency is significantly better than when the gas anchor inlets are above the perforations. The new results for intermittent flow, show, that for the conditions in the laboratory well, the entry port geometry did not have a significant impact on the separator efficiency. Also the efficiency of all gravity driven separators was limited by the liquid velocity inside the separator annulus. When the liquid velocity inside the separator averaged approximately 6 in/s or less, complete gas separation was observed. On the other hand, the centrifugal separator had a significantly larger capacity. The most efficient gravity separator achieved complete gas separation at liquid production rates as high as 250 BPD, while the Twister did so up to 390 BPD.

The possible effects of pipe materials on drinking water quality have been analyzed in the distribution system of the water treatment plant of "La La Concepciónâ " in Tegucigalpa, Honduras. "La La Concepciónâ " is a surface water reservoir experiencing biogeochemical cycling of manganese. Black water problems have been reported in the distribution system since 1998. An evaluation of the potential influence that PVC and iron pipes could have on the concentration of iron and manganese in drinking water, the effects caused by the presence of manganese in PVC and iron pipe surfaces, and residual chlorine and Pb concentrations in the distribution system was performed. The sampled neighborhoods received an intermittent service. Water was suspended for 8 hours every day due to water quantity problems in the city. Water and pipe samples were obtained for PVC and galvanized iron pipes because these constitute the majority of the infrastructure used for distribution systems in Honduras. Thermodynamic and kinetic conditions for possible manganese oxidation by chlorine and dissolved oxygen in the distribution system were also evaluated. As expected, total Fe concentrations were greater for first flush conditions from the iron pipe. Water samples obtained from the PVC pipe showed higher total Mn concentrations and more black color than those obtained from the iron pipe for both first flush and continuous flow conditions. Residual chlorine decayed relatively fast along the sampled section of the distribution system. Pb concentrations were detected on water samples obtained from PVC for first flush and continuous flow and on iron pipe for first flush. Preliminary experiments showed that manganese-oxidizing and -reducing bacteria were present in the walls of both PVC and iron pipes. Higher numbers of colony-forming microorganisms were recovered from iron (30-fold more) compared to PVC pipe sections. However, the majority of isolates from the PVC biofilm (8 of 10, 80 %) were capable of Mn-oxidation while only 35 % (11 of 31) of isolates from the iron biofilm sample demonstrated Mn-oxidation. This research demonstrates the importance of the different interactions between water and the infrastructure used for its supply in producing safe drinking water. Master of Science