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Prediction of transitional boundary layer properties for CFD software in engineering flowsThomson, Allan January 1997 (has links)
Two linear combination models for the transition zone in two-dimensional incompressible boundary layers have been programmed into the commercially available computational fluid dynamics software suite of programs, PHOENICS as a sink of momentum. It has been shown that it was possible to use a laminar velocity profile to predict laminar, transitional and turbulent boundary layer parameters. Method one, attributable to Fraser, Higazy and Milne (1994), was tested against a variety of flows including zero and constant adverse and favourable pressure gradients, and also the varying pressure gradient Rolls Royce T3C flows. The method gives good prediction of skin friction and transition length when the start of transition was in zero and favourable pressure gradient flows, but the transition length was always under predicted when the start of transition was in adverse pressure gradient. Method two, attributable to Solomon, Walker and Gostelow (1995) was tested in flows where the start of transition was in adverse pressure gradient. This method will probably give an improved prediction o f transition length, but the results were highly sensitive to the properties of the flow at the start of transition. It has been shown that in order to predict the start of transition using the Abu-Ghannam and Shaw (1980) correlation, a meaningful average of free stream turbulence intensity in the flow was required. It was found that a reasonable estimate could be found by integrating the free stream intensity value from the inlet and taking the average. A new method was developed to overcome the limitations of the Abu-Ghannam and Shaw correlation, and is based on the turbulent energy equation. The method used integrated averages of properties across the boundary layer starting from the leading edge and marching downstream. The boundary layer model was coupled to the free stream by a correlation which was found, using the Rolls Royce T3A, T3A-, T3B and T3C data, to be a function of free stream turbulence intensity, dissipation length scale and pressure gradient parameter. The method was found to give good prediction of the start of transition, and hence skin friction in the favourable pressure gradient flows. Unfortunately there was not enough data to extend this correlation to adverse pressure gradients.
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A numerical study for flow and heat transfer in a rectangular chemical vapor deposition chamberChiang, Yen-Chu 13 July 2004 (has links)
A method using CFD code PHOENICS to simulate flow and heat transfer in a rectangular chemical vapor deposition(CVD) chamber. We focus on the uniformity of heat and flow field. Two different kinds of boundary conditions at substrate, uniform wall heat flux and uniform wall temperature, are used to discuss the effects of the region of inlet, the distance from inlet to substrate, the region of outlet, Re number, and Pr number on uniformity of heat and flow field in chamber.
The study finds that high shear stress and high Nu number will happen on the edge of substrate, and they can not improve the heat and flow field uniformity, We suggest that the substrate should be smaller than susceptor. In the case of uniform wall heat flux on substrate, higher shear stress and Nu number on the edge of substrate would result from the condition that the region of inlet is too big. Higher shear stress and Nu number on the region of stagnant point would result from the condition that the region of inlet is too small. Both of them are not good for uniformity. Such kinds of situations also happen in the variable of the distance from inlet to substrate.
In uniform wall temperature on substrate, the condition of much higher Nu number on the edge of substrate is more obvious, which effects uniformity more seriously. The uniformity of Nu number could be improved effectively on the condition of region of inlet is 0.864*0.72, Higher distance from inlet to substrate.
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Estudo de óleo pesado envolto em água utilizando ferramenta CFD. / Study of heavy oil wrapped in water utilizing CFD tool.Siqueira, Fabio Coffani dos Santos de 12 February 2015 (has links)
A descoberta de petróleo na camada do Pré-Sal fez com que a Petrobras envestisse cerca de 240 bilhões de dólares. Uma etapa crítica desta indústria é o transporte de petróleo, que envolve o sistema água-óleo. O objetivo do presente trabalho é estudar uma corrente água-óleo em um tubo reto e em uma curva, com o intuito de gerar perfis de velocidades, pressões e densidades em CFD. Para as simulações desenvolvidas foram considerados: fluxo 3D, escoamento turbulento na fase óleo e escoamento laminar na fase água, isotérmico e incompressível. Foram realizados estudos nos estados estacionário e transiente. Foi desenvolvido o estudo de convergência da malha. As ferramentas do Phoenics utilizadas para representar a interação entre as fases foram o IPSA e o Algebraic Slip. O IPSA resolve as equações de Navier-Stokes para cada fase. No Algebraic Slip, postula-se que existe um meio contínuo em que existem vários componentes da fase dispersos, podendo estes ser gotas, bolhas ou partículas sólidas. A turbulência foi avaliada utilizando os modelos K- padrão e o K-, porém só houve redução considerável dos resíduos para o K- Padrão. As densidades geradas nas simulações em CFD foram comparadas visualmente com os resultados experimentais obtidos em trabalho anterior para fluxo multifásico. As quedas de pressão obtidas em simulação foram comparadas com os dados da literatura, onde foi possível observar a grande redução da perda de carga ao utilizar a técnica de envolver o óleo com um anel de água na tubulação. As simulações realizadas com o modelo Algebraic Slip, e o modelo de turbulência foram consideradas como validadas. / With the discovery of oil in the pre-salt layer, Petrobras was encouraged to invest about 240 billion dollars. A critical point of this industry is the oil transport, which encompasses oil-water system. The objective of the present work is to study the flow of water and oil into a tube and an elbow, in order to generate distributions of velocity, pressure and density by using a CFD tool. To develop simulations the following is assumed: 3D flow, turbulent flow in oil phase and laminar flow in water phase, isotherm and incompressible flow. Steady-state and transient studies have been done. The mesh convergence has been carried out. The IPSA and Algebraic slip were the Phoenics tools that were used to represent the phases interaction. The IPSA solves the Navier-Stokes equations for each phase. In the Algebraic Slip model, one assumes that a continuum mean exists where the other components are dispersed, which can be bubbles or solid particles. The turbulence was evaluated by using K- standard and K- models; however, the considerable reduction of residue to the K- Standard was observed. The densities modeled by CFD were visually compared to the experimental results that were obtained in a previous work for a multiphase flow. The simulations of head loss were compared to literature data, and it can be seen a big difference between the head loss that was obtained by using water and that no using water. The simulations of Algebraic Slip model and the use of turbulence model were considered as validated.
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Estudo de óleo pesado envolto em água utilizando ferramenta CFD. / Study of heavy oil wrapped in water utilizing CFD tool.Fabio Coffani dos Santos de Siqueira 12 February 2015 (has links)
A descoberta de petróleo na camada do Pré-Sal fez com que a Petrobras envestisse cerca de 240 bilhões de dólares. Uma etapa crítica desta indústria é o transporte de petróleo, que envolve o sistema água-óleo. O objetivo do presente trabalho é estudar uma corrente água-óleo em um tubo reto e em uma curva, com o intuito de gerar perfis de velocidades, pressões e densidades em CFD. Para as simulações desenvolvidas foram considerados: fluxo 3D, escoamento turbulento na fase óleo e escoamento laminar na fase água, isotérmico e incompressível. Foram realizados estudos nos estados estacionário e transiente. Foi desenvolvido o estudo de convergência da malha. As ferramentas do Phoenics utilizadas para representar a interação entre as fases foram o IPSA e o Algebraic Slip. O IPSA resolve as equações de Navier-Stokes para cada fase. No Algebraic Slip, postula-se que existe um meio contínuo em que existem vários componentes da fase dispersos, podendo estes ser gotas, bolhas ou partículas sólidas. A turbulência foi avaliada utilizando os modelos K- padrão e o K-, porém só houve redução considerável dos resíduos para o K- Padrão. As densidades geradas nas simulações em CFD foram comparadas visualmente com os resultados experimentais obtidos em trabalho anterior para fluxo multifásico. As quedas de pressão obtidas em simulação foram comparadas com os dados da literatura, onde foi possível observar a grande redução da perda de carga ao utilizar a técnica de envolver o óleo com um anel de água na tubulação. As simulações realizadas com o modelo Algebraic Slip, e o modelo de turbulência foram consideradas como validadas. / With the discovery of oil in the pre-salt layer, Petrobras was encouraged to invest about 240 billion dollars. A critical point of this industry is the oil transport, which encompasses oil-water system. The objective of the present work is to study the flow of water and oil into a tube and an elbow, in order to generate distributions of velocity, pressure and density by using a CFD tool. To develop simulations the following is assumed: 3D flow, turbulent flow in oil phase and laminar flow in water phase, isotherm and incompressible flow. Steady-state and transient studies have been done. The mesh convergence has been carried out. The IPSA and Algebraic slip were the Phoenics tools that were used to represent the phases interaction. The IPSA solves the Navier-Stokes equations for each phase. In the Algebraic Slip model, one assumes that a continuum mean exists where the other components are dispersed, which can be bubbles or solid particles. The turbulence was evaluated by using K- standard and K- models; however, the considerable reduction of residue to the K- Standard was observed. The densities modeled by CFD were visually compared to the experimental results that were obtained in a previous work for a multiphase flow. The simulations of head loss were compared to literature data, and it can be seen a big difference between the head loss that was obtained by using water and that no using water. The simulations of Algebraic Slip model and the use of turbulence model were considered as validated.
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Caracterização biológica e molecular do vírus da mancha clorótica de Clerodendrum ( Clerodendrum Chlorotic Spot Virus-CLCSV) / Biological and molecular characterization of Clerodendrum chlorotic spot virusGomes, Renata Takassugui 30 March 2009 (has links)
O gênero botânico Clerodendrum pertence à família Lamiaceae e compreende várias espécies ornamentais, geralmente trepadeiras, das quais as mais comumente cultivadas são coração-sangrento (C. x speciosum Tiejism. & Binn.) e lágrima-de-Cristo (C. thomsonae Balf.). Manchas cloróticas e necróticas em folhas de coração-sangrento foram observadas pela primeira vez em um jardim de Piracicaba, SP, associadas à infestação com Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae). Exames de secções de tecidos das lesões foliares ao microscópio eletrônico revelaram ocorrência de efeitos citopáticos do tipo nuclear e concluiu-se que os sintomas eram causados por um vírus transmitido por Brevipalpus (VTB), o qual foi tentativamente designado de mancha clorótica de Clerodendrum (Clerodendrum chlorotic spot virus- ClCSV). O ClCSV é transmitido mecanicamente de coração-sangrento para coração-sangrento e em ensaios preliminares foi transmitido mecanicamente e por Brevipalpus phoenicis para várias outras plantas, além da ocorrência de sua disseminação natural por esses ácaros para outras espécies. Ocorre a infecção sistêmica nas hospedeiras Chenopodium quinoa Will. e C. amaranticolor Coste & Reyn. infectadas com ClCSV caso as plantas sejam mantidas por cerca de 2 semanas entre 28-30 oC. Utilizando-se estas plantas realizou-se a purificação parcial do vírus. Este trabalho apresenta a caracterização biológica e molecular do ClCSV. Os resultados dos testes PTA-ELISA e RT-PCR demonstraram a detecção do ClCSV em diversas hospedeiras, além da análise da reação sorológica e molecular deste vírus com os outros VTBs do tipo nuclear. O seqüenciamento do produto de PCR revelou que as seqüências de nucleotídeos apresentaram similaridade com a polimerase de OFV (Orchid Fleck Virus), outro VTB do tipo nuclear. Além da identificação sorológica do vírus foram realizadas análises morfo-anatômicas para visualização das alterações causadas pelo ClCSV em tecidos de Clerodendrum x speciosum e em hospedeiras infectadas. / The botanical genus Clerodendrum belongs to the family Lamiaceae and includes several ornamental species, usually climbing, and heart-bloody (C. x speciosum Tiejism. & Binn.) and tear-in-Christ (C. thomsonae Balf. ) are among the most cultivated. Necrotic and chlorotic spots on leaves of heart-blood have been observed for the first time in a garden of Piracicaba, associated with an infestation of Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae). Sections of diseased tissues examined in the electron microscope revealed characteristic cytopathic effects of the nuclear type and concluded that the symptoms were caused by a virus transmitted by Brevipalpus (VTB), tentatively named Clerodendrum chlorotic spot virus (ClCSV). This virus is transmitted through mechanical inoculation from heart-bloody to heart-bloody and in preliminary tests mechanically and by mites for several other plants, in addition to the natural occurrence of its spread to other species. Systemic infection occurs in the host Chenopodium quinoa Will. and C. amaranticolor Coste & Reyn. infected with ClCSV if the plants are kept at 28-30°C for about 2 weeks. These plants were used for partial purification of vírus. This study presents the biological and molecular characterization of ClCSV. Through the PTA-ELISA and RT-PCR tests was possible to detect the ClCSV in different host, in addition to the analysis of serological and molecular reaction of this virus with other type of nuclear VTBs. From the sequencing of the PCR product was obtained from nucleotide sequences that showed similarity to the polymerase of OFV (Orchid Fleck Virus), another type of nuclear VTB. Morpho-anatomical analysis were performed to see the changes caused by ClCSV in tissues of Clerodendrum x speciosum and other infected hosts. It was possible to observe the occurrence of hypertrophy, cell plasmolisis and the reduction of starch grains in the áreas injured in all plants infected by ClCSV.
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Caracterização biológica e molecular do vírus da mancha clorótica de Clerodendrum ( Clerodendrum Chlorotic Spot Virus-CLCSV) / Biological and molecular characterization of Clerodendrum chlorotic spot virusRenata Takassugui Gomes 30 March 2009 (has links)
O gênero botânico Clerodendrum pertence à família Lamiaceae e compreende várias espécies ornamentais, geralmente trepadeiras, das quais as mais comumente cultivadas são coração-sangrento (C. x speciosum Tiejism. & Binn.) e lágrima-de-Cristo (C. thomsonae Balf.). Manchas cloróticas e necróticas em folhas de coração-sangrento foram observadas pela primeira vez em um jardim de Piracicaba, SP, associadas à infestação com Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae). Exames de secções de tecidos das lesões foliares ao microscópio eletrônico revelaram ocorrência de efeitos citopáticos do tipo nuclear e concluiu-se que os sintomas eram causados por um vírus transmitido por Brevipalpus (VTB), o qual foi tentativamente designado de mancha clorótica de Clerodendrum (Clerodendrum chlorotic spot virus- ClCSV). O ClCSV é transmitido mecanicamente de coração-sangrento para coração-sangrento e em ensaios preliminares foi transmitido mecanicamente e por Brevipalpus phoenicis para várias outras plantas, além da ocorrência de sua disseminação natural por esses ácaros para outras espécies. Ocorre a infecção sistêmica nas hospedeiras Chenopodium quinoa Will. e C. amaranticolor Coste & Reyn. infectadas com ClCSV caso as plantas sejam mantidas por cerca de 2 semanas entre 28-30 oC. Utilizando-se estas plantas realizou-se a purificação parcial do vírus. Este trabalho apresenta a caracterização biológica e molecular do ClCSV. Os resultados dos testes PTA-ELISA e RT-PCR demonstraram a detecção do ClCSV em diversas hospedeiras, além da análise da reação sorológica e molecular deste vírus com os outros VTBs do tipo nuclear. O seqüenciamento do produto de PCR revelou que as seqüências de nucleotídeos apresentaram similaridade com a polimerase de OFV (Orchid Fleck Virus), outro VTB do tipo nuclear. Além da identificação sorológica do vírus foram realizadas análises morfo-anatômicas para visualização das alterações causadas pelo ClCSV em tecidos de Clerodendrum x speciosum e em hospedeiras infectadas. / The botanical genus Clerodendrum belongs to the family Lamiaceae and includes several ornamental species, usually climbing, and heart-bloody (C. x speciosum Tiejism. & Binn.) and tear-in-Christ (C. thomsonae Balf. ) are among the most cultivated. Necrotic and chlorotic spots on leaves of heart-blood have been observed for the first time in a garden of Piracicaba, associated with an infestation of Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae). Sections of diseased tissues examined in the electron microscope revealed characteristic cytopathic effects of the nuclear type and concluded that the symptoms were caused by a virus transmitted by Brevipalpus (VTB), tentatively named Clerodendrum chlorotic spot virus (ClCSV). This virus is transmitted through mechanical inoculation from heart-bloody to heart-bloody and in preliminary tests mechanically and by mites for several other plants, in addition to the natural occurrence of its spread to other species. Systemic infection occurs in the host Chenopodium quinoa Will. and C. amaranticolor Coste & Reyn. infected with ClCSV if the plants are kept at 28-30°C for about 2 weeks. These plants were used for partial purification of vírus. This study presents the biological and molecular characterization of ClCSV. Through the PTA-ELISA and RT-PCR tests was possible to detect the ClCSV in different host, in addition to the analysis of serological and molecular reaction of this virus with other type of nuclear VTBs. From the sequencing of the PCR product was obtained from nucleotide sequences that showed similarity to the polymerase of OFV (Orchid Fleck Virus), another type of nuclear VTB. Morpho-anatomical analysis were performed to see the changes caused by ClCSV in tissues of Clerodendrum x speciosum and other infected hosts. It was possible to observe the occurrence of hypertrophy, cell plasmolisis and the reduction of starch grains in the áreas injured in all plants infected by ClCSV.
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