Tesi sul tema "Body fluids, mathematical models"
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Porumbel, Ionut. "Large Eddy Simulation of premixed and partially premixed combustion". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14050.
Testo completoObando, Vallejos Benjamín Alonso. "Mathematical models for the study of granular fluids". Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168158.
Testo completoThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely: In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids: the viscous nature of the intersticial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is an inequality (due to the plasticity of the fluid), and it involves a free boundary (due to the motion of the rigid body). The proof is achieved using an approximated problem and passing it to the limit. The approximated problems consider the regularization of the convex terms in the Bingham fluid and by using a penalty method to take into account the presence of the rigid body. In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface. As in the second problem, the proof is achieved using an approximated problem and passing it to the limit. The approximated problems consider a regularization of the convective term and a penalty method to take into account the presence of the rigid body.
CONICYT PFCHA/Doctorado Nacional/2014 - 2114090 y por CMM - Conicyt PIA AFB170001
Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274/document.
Testo completoThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274.
Testo completoThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
Lai, Wing-chiu Derek, e 黎永釗. "The propagation of nonlinear waves in layered and stratified fluids". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B29750441.
Testo completoZhang, Dongxiao. "Conditional stochastic analysis of solute transport in heterogeneous geologic media". Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186553.
Testo completoHavard, Stephen Paul. "Numerical simulation of non-Newtonian fluid flow in mixing geometries". Thesis, University of South Wales, 1989. https://pure.southwales.ac.uk/en/studentthesis/numerical-simulation-of-nonnewtonian-fluid-flow-in-mixing-geometries(eaee66ae-2e3d-44ba-9a5f-41d438749534).html.
Testo completoFanelli, Francesco. "Mathematical analysis of models of non-homogeneous fluids and of hyperbolic equations with low regularity coefficients". Doctoral thesis, SISSA, 2012. http://hdl.handle.net/20.500.11767/4420.
Testo completoFanelli, Francesco. "Mathematical analysis of models of non-homogeneous fluids and of hyperbolic equations with low regularity coefficients". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00794508.
Testo completoZipp, Robert Philip. "Turbulent mixing of unpremixed reactants in stirred tanks". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184832.
Testo completoCox, Barry James. "Mathematical modelling of nano-scaled structures, devices and materials". Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080129.102240/index.html.
Testo completoChaganti, Vasanta Gayatri. "Wireless body area networks : accuracy of channel modelling and prediction". Phd thesis, Canberra, ACT : The Australian National University, 2014. http://hdl.handle.net/1885/150112.
Testo completoRoss, Michael Paul 1963. "Evaluation of a two-dimensional electromagnetic model for hyperthermia treatment planning". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276780.
Testo completoCommon, David N. "Development of a system for the measurement of the static bulk modulus of fluids". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17579.
Testo completoWoudberg, Sonia. "Laminar flow through isotropic granular porous media". Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1320.
Testo completoChayantrakom, Kittisak. "Mathematical modelling of particle-fluid flows in microchannels". Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/1115.
Testo completoStott, J. O. "Resonances in two- and three-body nuclear systems". Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/843967/.
Testo completoWong, Heng Ho. "Modelling studies of the interaction between homogenisation, centrifugation and inclusion body dissolution /". Title page, contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phw8718.pdf.
Testo completoWelch, Charles Robert. "A full-engulfment engineering model, and its experimental and numerical verification, for the response of a rigid body to ground-shock". Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192008-063134/.
Testo completoBianchi, Luigi Amedeo. "Dyadic models of turbulence on trees". Doctoral thesis, Scuola Normale Superiore, 2013. http://hdl.handle.net/11384/85691.
Testo completoChayantrakom, Kittisak. "Mathematical modelling of particle-fluid flows in microchannels". Curtin University of Technology, Department of Mathematics and Statistics, 2009. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=129230.
Testo completoThe study consists of three parts. The first part of the research focuses on the transient flow of an incompressible Newtonian fluid through a micro-annual with a slip boundary. The flow of the fluid is governed by the continuity equation and the Navier-Stokes equations, and is driven by the pressure field with a timevarying pressure gradient. By using the Fourier series expansion in time and Bessel functions in space, an exact solution is derived for the velocity field. The velocity solution is then used to obtain the exact solutions for the flow rate and the stress field. Based on the exact solutions, the influence of the slip parameter on the flow behaviour is then investigated.
The second part of the research focuses on the particle-fluid flow in microchannels. The transport of fluid in the vessel is governed by the continuity equation and the transient Navier-Stokes equations, while the motion of the particles is governed by Newton’s laws. The particle-wall and particle-particle interactions are modelled by the interacting forces, while the particle-fluid interaction is described by the fluid drag force. A numerical scheme based on the finite element method and the Arbitary Lagrangian-Eulerian method is developed to simulate the motion of the particles and the fluid flow in the vessels. The influence of boundary slip on the velocity field in the fluid is also investigated numerically.
Based on the work in the second part, the third part of the research focuses onthe control of the movement of particles in the fluid by applying an external magneticfield to the system. Maxwell’s equations are used to model the magnetic fieldgenerated by the external magnetic source, and a finite element based numericalscheme is developed to solve the underlying boundary value problem for the magneticflux density generated. From the computed flux density and magnetic vectorpotential, the magnetic forces acting on the particles are determined. These magneticforces together with the drag force and the particle-particle interacting forcesdominate the behaviour of the particle motion. A numerical scheme, similar to thatfor the second part of the research, is then developed to study the fluid-particle flowin microchannels under magnetic forces, followed by a numerical investigation onthe influence of the magnetic forces on the particle flow behaviour.
Guertler, Siegfried. "Large scale computer-simulations of many-body Bose and Fermi systems at low temperature". Thesis, Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40887741.
Testo completoVan, Den Heever Emile. "Rheological model influence on pipe flow predictions for homogeneous non-Newtonian fluids". Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1030.
Testo completoThe reliable prediction of pressure drop versus flow rate for non-Newtonian pipe flow is important in many industrial processes. In laminar flow scale up is straightforward, but transitional velocity and turbulent flow predictions remain a practical problem. Various theoretical models exist, but nothing in literature shows conclusively which of these is the most reliable and consistent, nor is it evident what effect the choice of rheological model has on the predictions. The aim of this work was to i) evaluate the influence of different rheological models when used in existing prediction techniques for non-Newtonian flow ii) characterise each material type using selected (commonly used) rheological models and iii) predict laminar, transitional and turbulent pipe flow characteristics for each material type using existing prediction techniques, for comparison with experimental results. Only time-independent, homogeneous, non-Newtonian fluids in pipe sizes from 13mm to 200mm were investigated. Rheological models and laminar flow predictions used only the power law, Bingham plastic, Herschel-Bulkley, Casson and Hallbom yield plastic models. The techniques used to predict transitional velocity were Ryan & Johnson, Metzner-Reed, Hedström intersection method, Slatter and Hallbom. For turbulent flow the Newtonian approximation, Dodge & Metzner, Wilson & Thomas, Slatter, Hallbom modified Wilson & Thomas and the Bowen correlation methods were used. The study documents the relevant theory and presents an assessment of the influence of rheology on pipe flow predictions, summarised in terms of the practical performance of the various rheological model/prediction method combinations for the different materials. In laminar flow at practical pseudo shear rates (8V/D; taken as 40s-1) the choice of rheological model does not significantly influence pressure drop predictions. For yield-pseudoplastic materials (eg. kaolin) the Hedström intersection and the Slatter Reynolds number method with Bingham plastic or Casson rheology predicted transitional velocity most accurately. For Bingham plastic materials (eg. bentonite) the best predictions were obtained using the Metzner & Reed Reynolds number with Bingham plastic rheology, although similar results were observed for this technique with all rheologies. The transitional velocity for pseudoplastic materials (eg. CMC) was best predicted by the Slatter and Metzner & Reed Reynolds number methods, using power law or Casson rheology. For turbulent flow of yield pseudoplastic materials the Slatter method using the Casson rheology gave the most accurate predictions overall. Turbulent flow of Bingham plastic materials was best predicted by the Slatter, Hallbom pseudo fluid Nikuradse and Dodge & Metzner methods, using Bingham plastic, Casson or yield plastic rheology. For pseudoplastic materials the Slatter and Wilson & Thomas methods were the most accurate, when used with yield plastic or power law rheology. Transitionalal velocity and turbulent flow predictions for materials with a yield stress vary significantly with rheological model. Laminar data should therefore be examined thoroughly and rheological models fitted with care. For pseudoplastic fluids there is little difference in predictions between the various techniques as long as power law rheology is used.
RODRIGUES, JUNIOR ORLANDO. "Aplicacao de modelos metabolicos para a determinacao de funcoes de excrecao e retencao". reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10344.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Guo, Jiajie. "Effects of joint constraints on deformation of multi-body compliant mechanisms". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45971.
Testo completoTerblanche, Luther. "The prediction of flow through two-dimensional porous media". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1722.
Testo completoWhen considering flow through porous media, different flow regimes may be identified. At very small Reynolds numbers the relation between the pressure gradient and the velocity of the fluid is linear. This flow regime ...
Said, Munzir. "Computational optimal control modeling and smoothing for biomechanical systems". University of Western Australia. Dept. of Mathematics and Statistics, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0082.
Testo completoXufen, Wu. "Numerical modeling of modified Newtonian dynamics in galaxies : testing the external field effects". Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1706.
Testo completoVENTURINI, LUZIA. "Estudo de incertezas no monitoramento in vivo utilizando a tecnica de Monte Carlo". reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11188.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Eicholtz, Matthew R. "Design and analysis of an inertial properties measurement device for manual wheelchairs". Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34677.
Testo completoLavarda, Jairo Vinícius. "Convecção natural de fluidos de lei de potência e de Bingham em cavidade fechada preenchida com meio heterogêneo". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1306.
Testo completoVários estudos numéricos investigaram cavidades fechadas sob o efeito da convecção natural preenchidas com fluidos newtonianos generalizados (FNG) nos últimos anos pelas aplicações diretas em trocadores de calor compactos, no resfriamento de sistemas eletrônicos e na engenharia de polímeros. Neste trabalho é realizada a investigação numérica do processo de convecção natural de fluidos de lei de Potência e de Bingham em cavidades fechadas, aquecidas lateralmente e preenchidas com meios heterogêneos e bloco centrado. O meio heterogêneo é constituído de blocos sólidos, quadrados, desconectados e condutores de calor. Como parâmetros são utilizados a faixa de Rayleigh de 104 à 107, índice de potência n de 0, 6 à 1, 6, número de Bingham de 0, 5 até Bimax , sendo investigado da influência do número de Prandtl para cada modelo de fluido. Nas cavidades com meio heterogêneo são utilizadas as quantidades de blocos de 9, 16, 36 e 64, mantendo-se a razão entre a condutividade térmica do sólido e do fluido κ = 1. Para as cavidades com bloco centrado, são utilizados os tamanhos adimensionais de 0, 1 à 0, 9 com κ = 0, 1; 1 e 10. A modelagem matemática é realizada pelas equações de balanço de massa, de quantidade de movimento e de energia. As simulações são conduzidas no programa comercial ANSYS FLUENT R . Inicialmente são resolvidos problemas com fluidos newtonianos em cavidade limpa, seguida de cavidade preenchida com meio heterogêneo e posteriormente bloco centrado para validação da metodologia de solução. Na segunda etapa é realizada o estudo com os modelos de fluidos de lei de Potência e de Bingham seguindo a mesma sequência. Os resultados são apresentados na forma de linhas de corrente, isotermas e pelo número de Nusselt médio na parede quente. De maneira geral, a transferência de calor na cavidade é regida pelo número de Rayleigh, tamanho e condutividade térmica dos blocos, pelo índice de potência para o modelo de lei de Potência e do número de Bingham para o modelo de Bingham. O número de Prandtl tem grande influência nos dois modelos de fluidos. O meio heterogêneo reduz a transferência de calor na cavidade quando interfere na camada limite térmica para ambos os fluidos, sendo feita uma previsão analítica para o fluido de lei de Potência. Para bloco centrado, a interferência na camada limite com fluido de lei de Potência também foi prevista analiticamente. A transferência de calor aumentou com bloco de baixa condutividade térmica e pouca interferência e com bloco de alta condutividade térmica e grande interferência, para ambos os fluidos.
Many studies have been carried out in square enclosures with generalized Newtonian fluids with natural convection in past few years for directly applications in compact heat exchangers, cooling of electronics systems and polymeric engineering. The natural convection in square enclosures with differently heated sidewalls, filled with power-law and Bingham fluids in addition with heterogeneous medium and centered block are analyzed in this study. The heterogeneous medium are solid, square, disconnected and conducting blocks. The parameters used are the Rayleigh number in the range 104 - 107 , power index n range of 0, 6 - 1, 6, Bingham number range of 0, 5 - Bimax , being the influence of Prandtl number investigated for each fluid model. The number of blocks for heterogeneous medium are 9, 16, 36 and 64, keeping constant solid to fluid conductive ratio, κ = 1. For enclosures with centered block are used the nondimensional block size from 0, 1 to 0, 9, with solid to fluid conductive ratio in range κ = 0, 1; 1 and 10. Mathematical modeling is done by mass, momentum and energy balance equations. The solution of equations have been numerically solved in ANSYS FLUENT R software. Firstly, numerical solutions for validation with Newtonian fluids in clean enclosures are conducted, followed by enclosures with heterogeneous medium and centered block. Subsequently, numerical solutions of power-law and Bingham fluids with same enclosures configurations are conducted. The results are reported in the form of streamlines, isotherms and average Nusselt number at hot wall. In general, the heat transfer process in enclosure is governed by Rayleigh number, size and thermal conductivity of the blocks, power index n for power-law fluid and Bingham number for Bingham fluid. Both fluid models are very sensitive with Prandtl number changes. Heterogeneous medium decrease heat transfer in enclosure when affects thermal boundary layer for both fluid models. One analytical prediction was made for power-law fluid. An increase in heat transfer occurs with low thermal conductivity block and few interference and with high thermal conductivity block and great interference, for both fluids.
Beraldo, Lucas Menghin. "Modelagem matemática para estimativa da gordura corporal baseada em densitômetro radiológica". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2634.
Testo completoThe overfat is associated with many methabolic, psycological and structural diseases. The adolescence is indicated as the critical period for the development of habits associated with fat accumulation like physical inactivity, poor diet and sedentarism. Thus, this is a important moment to monitorig the population aiming the reduction of obesity and associated disease. The golden standard to evaluate the body fatness is the dual-energy x-ray absorptiometry. However, its laboratorial aspect prevents a wide use. This way, simpler techniques as the skinfold measurement should be model from more exact techniques for this monitoring. The existing models were developed with foreign populations that don't resemble the Curitiba Metropolitan Region habitants. This could lead to evaluation and diagnostic errors. Thus, the aim of this study is to product a model of body fatness analysis appropriate to children and adolescents from the Curitiba Metropolitan Region. Two sample were selected, the first one composed by 567 healthy adolescents aged between 10 and 18 years; the other one composed by 63 children with cerebral palsy between 3 and 10 years. The groups have both genders. The data of weight, height, age and skinfold thickness were collected, beyond the body composition evaluation by radiologic densitometry. The fatness percentage obtained by different skinfold and other anthopometric mesures equations among the adolescents was compared with the obtained by densitometry presenting associations below indicated (CCC<0,900). A tendency of underestimation by the skinfold equations was found, that resulted in higher specificity values and low sensitivity (being specificity the relative quantity of true negatives among those who do not have de clinical condition, and the sensitivity the relations of true positives amons those who have the considered condition). This indicates a major quantitaty of false negatives, that leads many overfat adolescents to be classify as eutrophic. The developed classificatory model for adolescents obtained an adjustment of R2 Negelkerke=0,829, sensitivity of 99,0% and specificity of 82,7% presenting diagnostic's indicators above that obtained by skinfold equations and BMI. For the children with cerebral palsy was developed a fat mass estimation model with adjustment of R2 =0,950 and standard error of estimative of 1,039. The equations used to convert the skinfold in body fatness measures were found to be inadequate for aplication in adolescents from Curitiba Metropolitan Region. The aplication of logistic and linear regression techniques have presented positive results, even from modeling in the children with cerebral palsy sample.
Mitishita, Rodrigo Seiji. "Avaliação experimental da transmissão de pressão em tubulações preenchidas por fluidos viscoplásticos". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2598.
Testo completoFluidos de perfuração apresentam comportamento viscoplástico, que é definido por uma tensão limite de escoamento. Se a tensão imposta não supera a tensão limite de escoamento, o material se comporta como um sólido elástico, e quando esta tensão é excedida, o fluido escoa como um líquido viscoso. Durante o processo de perfuração de poços de petróleo, válvulas posicionadas na extremidade da coluna de perfuração são atuadas por diferenças de pressão no fluido. Argumenta-se, entretanto, que pressões aplicadas na superfície não são totalmente transmitidas até a válvula, impedindo sua operação. Logo, a transmissão de pressão em fluidos viscoplásticos demanda mais estudo. Para suprir a falta de estudos experimentais sobre o assunto, uma avaliação experimental da transmissão de pressão em um fluido viscoplástico é realizada neste trabalho. O aparato experimental construído para este propósito consiste de uma longa tubulação em formato helicoidal (serpentina) mantida sob temperatura controlada, ao longo da qual estão instalados transdutores de pressão relativa. O fluido é bombeado a uma vazão controlada por uma bomba do tipo helicoidal. Durante os testes, o fluido de trabalho é pressurizado na serpentina até um certo patamar ao mesmo tempo em que as pressões são medidas. Os resultados dos testes com fluidos viscoplásticos corroboram a literatura, que afirma que um fluido com tensão limite de escoamento confinado em uma tubulação fechada não transmite totalmente a pressão imposta na entrada ao longo do restante da tubulação. Além disso, foi observado que a diferença de pressão entre dois pontos da tubulação quando o fluido está em repouso é proporcional à tensão limite de escoamento deste fluido. Os resultados experimentais foram comparados com resultados de simulações numéricas de dois modelos matemáticos desenvolvidos no Centro de Pesquisas em Reologia e Fluidos Não newtonianos (CERNN), com boa concordância.
Drilling fluids exhibit a viscoplastic behavior, which is defined by a yield stress. If the stress imposed to the fluid does not surpass the yield stress, the material behaves like an elastic solid; if the yield stress is exceeded, it flows like a viscous liquid. In well drilling operations, some valves installed on the drillpipe near the bottom of the hole are actuated by pressure differences in the drilling fluid. However, it has been argued that the pressure applied at the surface is not fully transmitted to the valve’s position, preventing its actuation. Therefore, the pressure transmission in viscoplastic fluids demands further investigation. In order to compensate for the lack of experimental studies about the problem, an experimental analysis of the pressure transmission in yield stress fluids has been performed in this work. The experimental rig consists of a long thermally-controlled helical pipe, on which are installed relative pressure transducers. Fluid is displaced by a helical pump at a controlled flow rate. During the experiments, the fluid is pressurized inside the closed pipeline while the pressures are measured and recorded. The results showed that, in agreement with literature, the pressure at one end of a closed pipeline filled with a yield stress fluid is not fully transmitted to the other end. Moreover, it was observed that the pressure gradient in the pressurized fluid is proportional to its yield stress, which indicates a relation between pressure transmission and the presence and magnitude of the yield stress. The experiments were compared to simulation work developed at the Research Center for Rheology and Non-Newtonian Fluids with good agreement.
Ripka, Wagner Luis. "Modelos matemáticos para estimativa da gordura corporal de adolescentes utilizando dobras cutâneas, a partir da absorciometria de raios-X de dupla energia". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2865.
Testo completoIntroduction: Studies have found a transition from obesity of the adult population to children and adolescents, which in turn, can lead to clinical manifestations, such as: coronary diseases, type 2 diabetes, and psychosocial complications increasingly early. However, methods for evaluating nutritional status for this age group, mainly involving low cost techniques such as skinfold thickness measurements (ST), are imprecise in Brazilian studies. Factor which can lead to a mistaken interpretation of the body composition of the evaluated ones. Objective: To develop new mathematical models, based on DC measurements, based on dual energy X-rays absorptiometry (DXA), to estimate fat mass (G) in adolescents. Methods: This was an exploratory descriptive study in which 416 male adolescents aged 12 to 17 years were evaluated, 42 of whom were separated to compose the study validation sample. Measurements of total body mass, stature, waist and hip circumference were obtained, nine anatomical points based on ST: biceps, triceps, subscapular, pectoral, mid axillary, abdominal, suprailiac, thigh and calf muscles, as well as G and bone mineral density (BMD) measured with DXA technology. For the development of the equations, a multiple linear regression model was used by the ordinary least square (OLS) method. Results: The group had a mean body mass index (BMI) of 21.25± 4.12 kg / m² and %G = 20.57 ± 5.80%. From %G, the prevalence of excess fat was verified in 38.3% of adolescents. The impact of fat on adolescent BMD indicated an association in the order of r = -0.358; P <0.005, with BMD reduction up to 14% for the spine region in adolescents with obesity compared to eutrophic. The development of new mathematical models that meet criteria of high coefficient of determination (R²), low standard error of estimation (SEE), control of colinearity, residue normalities, homoscedasticity and practicality, allowed the presentation of three options with R² = 0.932 and SEE 1.79; R² = 0.912 and SEE = 1.78; R² = 0.850 and SEE = 1.87, respectively. In all the options, the variables age and height were employed, as well as triceps and subscapular ST. Conclusion: The results obtained evidenced the possibility of developing new mathematical models for the evaluation of body fat in adolescents with results superior to the existing models in the literature.
Gregory, Paul. "Flow over a body of revolution in a steady turn". 2006. http://repository.unimelb.edu.au/10187/2849.
Testo completoLai, Kwok Leung. "A numerical study of bluff body flow / submitted by Kwok Leung Lai". Thesis, 2000. http://hdl.handle.net/2440/19895.
Testo completoIncludes bibliographical references (leaves 459-472).
System requirements for accompanying CD-ROM: Macintosh or IBM compatible computer. Other requirements: Adobe Acrobat Reader.
xxxvi, 473 leaves ; ill. ; 30 cm. + 1 computer optical disk (4 3/4 in.)
A numerical scheme, based on discrete-vortex and surface-vorticity boundary-integral methods, has been developed for stimulating time dependent, two-dimensional, viscous flow over arbitary arrays of solid bodies of arbitary cross-section
Thesis (Ph.D.) -- University of Adelaide, Dept. of Mechanical Engineering, 2001
Lai, Kwok Leung. "A numerical study of bluff body flow / submitted by Kwok Leung Lai". 2000. http://hdl.handle.net/2440/19895.
Testo completoIncludes bibliographical references (leaves 459-472).
System requirements for accompanying CD-ROM: Macintosh or IBM compatible computer. Other requirements: Adobe Acrobat Reader.
xxxvi, 473 leaves ; ill. ; 30 cm. + 1 computer optical disk (4 3/4 in.)
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
A numerical scheme, based on discrete-vortex and surface-vorticity boundary-integral methods, has been developed for stimulating time dependent, two-dimensional, viscous flow over arbitary arrays of solid bodies of arbitary cross-section
Thesis (Ph.D.)--Adelaide University, Dept. of Mechanical Engineering, 2001
"Some studies on viscous fluids". Thesis, 2011. http://library.cuhk.edu.hk/record=b6075216.
Testo completoIn the first part, we study the issue of the inviscid limit of the incompressible Navier-Stokes equations on the general smooth domains for completely slip boundary conditions. We verify an asymptotic expansion which involves a weak amplitude boundary layer with the same thickness as in the Prantle's theory. We improve the better regularity for the boundary layer and obtain the uniform Lp--estimates (3 < p ≤ 6) of the remainder. Then we improved these estimates to H 1--estimates. It is shown that the viscous solution converges to the solution of Euler equation in C([0, T]; H1(O)) as the viscosity tends to zero.
In the second part, we consider the non-stationary problems of a class of non-Newtonian fluid which is a power law fluid with p > 3nn+2 in the half space with slip boundary conditions. We present the local pressure estimate with the Navier's slip boundary conditions. Using these estimates and an Linfinity -- truncation method, we can obtain that this system has at least one required weak solution.
In this thesis, we study several issues involving incompressible viscous fluids with the slip boundary conditions and the motions of fluid-solid interactions.
Zang, Aibin.
Adviser: Zhouping Xin.
Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 128-141).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Antiohos, Andrew. "The control of turbulent flows around bluff bodies by means of spanwise sinusoidal profiles". Thesis, 2014. https://vuir.vu.edu.au/25796/.
Testo completo"Some studies on fluid-solid interactions". Thesis, 2010. http://library.cuhk.edu.hk/record=b6074914.
Testo completoThe main part is the study of the motion of a rigid body immersed in an incompressible fluid. First, for the case of 2D ideal flow, a global weak solution is derived. Second, for the case of viscous flow in 3D, the problem is investigated in the Lp--framework. We get a decomposition of Lp-space associated with the problem. Then We prove that the corresponding semigroup is analytic in L65 R3∩L pR3 (p ≥ 2). Our result yields a local in time existence and uniqueness of strong solutions taking initial data in L65 R3∩L pR3 (p ≥ 3).
The other part is some research about micro-macro models of polymeric fluids. We provide a new proof for the global well-posedness of the coupling systems in 2D.
Wang, Yun.
Adviser: Zhouping Xin.
Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 112-119).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Hood, Lindsay Malcolm. "Computer simulation of shear flow in simple fluids". Phd thesis, 1989. http://hdl.handle.net/1885/136598.
Testo completoHsu, Chun-chia. "Range of motion of beetle body as a function of leg parameters". Thesis, 1991. http://hdl.handle.net/1957/36921.
Testo completoGraduation date: 1992
Foo, Chee Kit. "Range of motion of beetle body as a function of foot positions". Thesis, 1991. http://hdl.handle.net/1957/38136.
Testo completoGraduation date: 1991
Gladkikh, Mikhail Nikolaevich. "A priori prediction of macroscopic properties of sedimentary rocks containing two immiscible fluids". Thesis, 2005. http://hdl.handle.net/2152/1551.
Testo completoAmler, Thomas [Verfasser]. "Detection of particles transported in weakly compressible fluids : mathematical models, analysis, and simulations / Thomas Georg Amler". 2011. http://d-nb.info/1010249770/34.
Testo completoDawkrajai, Pinan. "Temperature prediction model for a producing horizontal well". Thesis, 2006. http://hdl.handle.net/2152/2710.
Testo completoSun, Yang 1959 Apr 19. "Nonlinear dynamic response of cable/lumped-body system by direct integration with suppression". Thesis, 1992. http://hdl.handle.net/1957/36218.
Testo completoWang, Cheng-Ching 1975. "Two problems in many-body physics". 2008. http://hdl.handle.net/2152/18162.
Testo completotext
Rhee, Brian Kanghee. "Enhancement of mass transfer coefficient in three-phase magnetically stabilized fluidized bed". Thesis, 1998. http://hdl.handle.net/1957/33757.
Testo completoHong, Zheng Hao, e 洪政豪. "Tribological performance study and mathematical models establishment of line contact body in considering of surface roughness". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/47297169372532279554.
Testo completo