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ABDU, ALINE AMARAL QUINTELLA. "NON-NEWTONIAN FLUID DISPLACEMENT IN ANNULI." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29332@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Na indústria do petróleo são comuns processos envolvendo deslocamentos de um fluido pelo outro, como nos processos de completação e cimentação de poços. A eficiência desses deslocamentos é de suma importância, garantindo a vida útil do poço. A operação é considerada adequada quando ocorre uma distribuição homogênea da pasta de cimento na parede do poço. No presente trabalho um estudo experimental e numérico do deslocamento de fluidos em espaço anular foi realizada. Para os testes experimentais um simulador físico de um poço em escala foi construído. As equações de conservação de massa e momento foram resolvidas através do método de volumes finitos, utilizando os programas Fluent e OpenFOAM. Para a modelagem multifásica foi utilizado o método volume-of-fluid (VOF). No estudo, a avaliação da influência de parâmetros reológicos, razões de densidade e viscosidade, geometria do poço e vazão de bombeio foi realizada com o objetivo de otimizar o processo de cimentação. Os fluidos utilizados foram fluidos modelos e reais, newtonianos e não newtonianos. A eficiência de deslocamento foi avaliada através da configuração da interface entre os fluidos e através da determinação do da densidade da mistura na saída do anular ao longo do tempo.
Displacement of one fluid by another is a common process at petroleum industry, as completion and cementing operations of oil wells. The success of these fluids displacement guarantee the lifetime of the wells. The adequate operation occurs when the cement slurry distribution at the wall is homogeneous. In this work, experimental and numerical studies of Newtonian and non-Newtonian fluid displacement through annuli are performed. The experiments are performed using a scaled oil well model. The numerical solution of the governing conservation equations of mass and momentum is obtained using the finite volume technique and Fluent and OpenFOAM softwares. The multiphase modeling is performed using the volume of fluid (VOF) method. The effect of rheological parameters, density and viscosity ratios, geometry configuration, and flow rate on displacement efficiency was evaluated to optimize cementing operation. Tests were performed using model and real fluids, Newtonian and non-Newtonian. The displacement efficiency was evaluated analyzing the interface between fluids and measuring the density of the mixture at the annuli outlet through time.
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Gouldson, Iain William. "The flow of Newtonian and non-Newtonian fluids in an annular geometry." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243035.
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Keiller, Robert A. "Non-Newtonian extensional flows." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315030.
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Mennad, Abed. "Singular behaviour of Non-Newtonian fluids." Thesis, Peninsula Technikon, 1999. http://hdl.handle.net/20.500.11838/1253.
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Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1999Since 1996, a team at the Centre for Research in Applied Technology (CRATECH) at Peninsula Technikon, under NRF sponsorship and with industrial co-operation, has been involved in the simulation of Non-Newtonian flow behaviour in industrial processes, in particular, injection moulding of polymers. This study is an attempt to deal with some current issues of Non-Newtonian flow, in small areas, from the viewpoint of computational mechanics. It is concerned with the numerical simulation of Non-Newtonian fluid flows in mould cavities with re-entrant corners. The major complication that exists in this numerical simulation is the singularity of the stresses at the entry of the corner, which is responsible for nonintegrable stresses and the propagation of solution errors. First, the study focuses on the derivation of the equations of motion of the flow which leads to Navier- Stokes equations. Thereafter, the occurrence of singularities in the numerical solution of these equations is investigated. Singularities require special attention no matter what numerical method is used. In finite element analysis, local refinement around the singular point is often employed in order to improve the accuracy. However, the accuracy and the rate of convergence are not, in general, satisfactory. Incorporating the nature of singularity, obtained by an asymptotic analysis in the numerical solution, has proven to be a very effective way to improve the accuracy in the neighborhood of the singularity and, to speed up the rate of convergence. This idea has been successfully adopted in solving mainly fracture mechanics problems by a variety of methods: finite difference, finite elements, boundary and global elements, and spectral methods. In this thesis, the singular finite elements method (SFEM), similar in principle to the crack tip element used in fracture mechanics, is proposed to improve the solution accuracy in the vicinity of the singular point and to speed up the rate of convergence. This method requires minor modifications to standard finite element schemes. Unfortunately, this method could not be implemented in this study due to the difficulty in generating the mesh for the singular element. Only the standard finite element method with mesh refinement has been used. The results obtained are in accordance with what was expected.
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Callahan, Thomas Patrick. "Non-Newtonian fluid injection into granular media." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39618.
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The process of fluid injection into granular media is relevant to a wide number of applications such as enhanced oil recovery, grouting, and the construction of permeable reactive barriers. The response of the subsurface is dependent on multiple factors such as in-situ stresses, fluid properties, flow rate, and formation type. Based on these conditions a variety of response mechanisms can be initiated ranging from simple porous infiltration to hydraulic fracturing.
Currently, the mechanics of fluid injection into competent rock are well understood and can be sufficiently modeled using linear elastic fracture mechanics. Because the grains in rock formations are individually cemented together, they exhibit cohesion and are able to support tensile stresses. The linear elastic method assumes tensile failure due to stress concentrations at the fracture tip. A fracture propagates when the stress intensity factor exceeds the material toughness (Detournay, 1988)
However, understanding fluid injection in cohesionless granular media presents a much larger obstacle. Currently, no theoretical models have been developed to deal with granular media displacements due to fluid injection. Difficulty arises from the complexity of fluid rheology and composition used in engineering processes, the strong coupling between fluid flow and mechanical deformation, the non-linear response of subsurface media, and the multi-scale nature of the problem.
The structure of this thesis is intended to first give the reader a basic background of some of the fundamental concepts for non-Newtonian fluid flow in granular media. Fluid properties as well as some interaction mechanisms are described in relation to the injection process. Next, the results from an experimental series of injection tests are presented with a discussion of the failure/flow processes taking place.
We developed a novel technique which allows us to visualize the injection process by use of a transparent Hele-Shaw cell. Specifically, we will be using polyacrylamide solutions at a variety of concentrations to study non-Newtonian effects on the response within the Hele-Shaw cell. By performing tests at a range of solution concentrations and injection rates we are to be able to identify a transition from an infiltration dominated flow regime to a fracturing dominated regime.
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Khahledi, Morakane Charlotte. "Non-Newtonian fluid flow measurement using sharp crested notches." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1038.
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Master of Technology: Civil Engineering
In the Faculty of Engineering
At the Cape Peninsula University of Technology
2014Notches, particularly rectangular and V shaped are the cheapest and most common devices used to measure the flow rate of water in open channels. However, they have not been used to measure the flow rate of non-Newtonian fluids. These viscous fluids behave differently from water. It is difficult to predict the flow rate of such fluids during transportation in open channels due to their complex viscous properties. The aim of this work was to explore the possibility of extending the application of especially rectangular and V-shaped notches to non-Newtonian fluids. The tests reported in this document were carried out in the Flow Process and Rheology Centre laboratory. Notches fitted to the entrance of a 10 m flume and an in-line tube viscometer were calibrated using water. The in-line tube viscometer with 13 and 28 mm diameter tubes was used to determine the fluid rheology. Flow depth was determined using digital depth gauges and flow rate measurements using magnetic flow meters. Three different non-Newtonian fluids, namely, aqueous solutions of Carboxymethyl Cellulose (CMC) and water-based suspensions of kaolin and bentonite were used as model non-Newtonian test fluids. From these the coefficient of discharge (Cd) values and appropriate non-Newtonian Reynolds numbers for each fluid and concentration were calculated. The experimental values of the coefficient of discharge (Cd) were plotted against three different definitions of the Reynolds number. Under laminar flow conditions, the discharge coefficient exhibited a typical dependence on the Reynolds number with slopes of ~0.43-0.44 for rectangular and V notches respectively. The discharge coefficient was nearly constant in the turbulent flow regime. Single composite power-law functions were used to correlate the Cd-Re relationship for each of the two notch shapes used. Using these correlations, the Cd values could be predicted to within ±5% for the rectangular and V notches. This is the first time that such a prediction has been done for a range of non-Newtonian fluids through sharp crested notches. The research will benefit the mining and food processing industries where high concentrations of non-Newtonian fluids are transported to either disposal sites or during processing.
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Vayssière, Brandão Pedro <1993>. "Linear and nonlinear thermal instability of Newtonian and non-Newtonian fluid saturated porous media." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10143/1/VayssiereBrandao_Pedro_PhD_Thesis.pdf.
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The present work aims to investigate the influence of different aspects, such as non-standard steady solutions, complex fluid rheologies and non-standard porous-channel geometries, on the stability of a Darcy-Bénard system. In order to do so, both linear and nonlinear stability theories are considered. A linear analysis focuses on studying the dynamics of the single disturbance wave present in the system, while its nonlinear counterpart takes into consideration the interactions among the single modes. The scope of the stability analysis is to obtain information regarding the transition from an equilibrium solution to another one, and also information regarding the transition nature and the emergent solution after the transition. The disturbance governing equations are solved analytically, whenever possible, and numerical by considering different approaches. Among other important results, it is found that a cylinder cross-section does not affect the thermal instability threshold, but just the linear pattern selection for dilatant and pseudoplastic fluid saturated porous media. A new rheological model is proposed as a solution for singular issues involving the power-law model. Also, a generalised class of one parameter basic solutions is proposed as an alternative description of the isoflux Darcy--Bénard problem. Its stability is investigated.
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Vongvuthipornchai, Somporn. "Well test analysis for non-Newtonian fluid flow /." Access abstract and link to full text, 1985. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8603796.
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Ketheeswaranathan, Nishanthi. "Rehological study of non-Newtonian fluid through microchannels." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540775.
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Yim, Samson Sau Shun. "The effect of flow stability on residence time distribution of Newtonian and non-Newtonian liquids in couette flow." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264191.
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Prabhanjan, Devanahalli G. "Influence of coil characteristics on heat transfer to Newtonian fluids." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36910.
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A water bath thermal Processor was designed and built to study the influence of helical coil characteristics on heat transfer to Newtonian fluids like water and base oil with three different viscosities. The system consisted of a thermally insulated water bath, an electric heater, pump to re-circulate water in the bath and for pumping the processing fluid through the coil, copper helical coils and a storage tank for the processing fluid.Comparative study has shown that the outer and total heat transfer coefficients were significantly lower in natural than in forced convection water bath. However, inner heat transfer coefficient was not significantly affected. Flow rate as low as 0.001 m.s-1 in the water bath improved the outer and total heat transfer coefficients by 35 and 22% respectively. One could expect a higher rate with an increase in water re-circulation rate inside the water bath. Percent rise in heat transfer was limited to seven with respect to inner heat transfer. With the Pearson correlation, it was possible to express total heat transfer rate directly in terms of outer and inner rates. Significant interactions were observed between variables and constants.
Experiments with 2 pitch cases were conducted with water to water heat transfer using coils to determine the Nusselt number correlation for natural convection. Characteristic lengths were changed in the models. The Nusselt number was under-predicted by 25 to 37% for water bath temperatures of 75° and 95°C respectively. Flow rate inside the coil had slight effect on Nusselt number due to change in the temperature gradient along the length of the coil.
Studies conducted with three base oils have shown significant difference in viscosity after heating the oil for several turns. Each fluid was heated in a distinct flow regime. The observed Nusselt number inside the coil for low Reynolds number was as high as an order of magnitude than the predicted values calculated by Seider-Tate relation for laminar flow. Vorticies formed associated with the eddy structure could very well be the cause for this kind of rise in the value.
Preliminary study conducted has shown a higher rise in temperature of processing fluid in case of helical coil compared to that of a straight tube. Larger the diameter of the tube better was the heat transfer. An elevated bath temperature had higher heat transfer.
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Van, Sittert Fritz Peter. "The effect of pipe roughness on non-Newtonian turbulent flow." Thesis, Cape Technikon, 1999. http://hdl.handle.net/20.500.11838/1035.
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Thesis (MTech (Civil Engineering))--Cape Technikon, Cape Town, 1999Pipe roughness is known to greatly increase the turbulent flow friction factor for Newtonian fluids. The well-known Moody diagram shows that an order of magnitude increase in the friction is possible due to the effect of pipe roughness. However, since the classical work of Nikuradse (1926 -1933), very little has been done in this area. In particular, the effects that pipe roughness might have on non-Newtonian turbulent flow head loss, has been all but totally ignored. This thesis is directed at helping to alleviate this problem. An experimental investigation has been implemented in order to quantify the effect that pipe roughness has on non-Newtonian turbulent flow head loss predictions. The Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town, has been rebuilt and refined at the Cape Technikon and is being used for research in this field. The BBTV has been fitted with pipes of varying roughness. The roughness of smooth P\'C pipes was artificially altered using methods similar to those of Nikuradse. This has enabled the accumulation of flow data in laminar and turbulent flow in pipes that are both hydraulically smooth and rough Newtonian and non-Newtonian fluids have been used for the tests. The data have been subjected to analysis using various theories and scaling laws. The strengths and problems associated with each approach are discussed and It is concluded that roughness does have a significant effect on Newtonian as well as non-Newtonlan flow.
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Götz, Dario [Verfasser]. "Three topics in fluid dynamics: Viscoelastic, generalized Newtonian, and compressible fluids / Dario Götz." München : Verlag Dr. Hut, 2012. http://d-nb.info/1029400113/34.
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Gallup, Benjamin H. (Benjamin Hodsdon) 1982. "High speed imaging of transient non-Newtonian fluid phenomena." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32815.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 51).
In this thesis, I investigate the utility of high speed imaging for gaining scientific insight into the nature of short-duration transient fluid phenomena, specifically applied to the Kaye effect. The Kaye effect, noted by A. Kaye in the March 9, 1963 issue of Nature, is the deflection and rebound of a free-falling non-Newtonian fluid stream incident on a pool of the same fluid. The effect was successfully reproduced using Suave[TM] shampoo, and imaged using the Phantom[TM] High Speed Video system. This task involved developing a knowledge of the photographic process as applied to high speed imaging, and of non-Newtonian fluid mechanics. No precisely reproducible method for producing rebounding streams was found, and behavior contrary to the existing body of observation were noted. In conclusion, areas that merited further investigation and potential variables of interest to future Kaye effect research are discussed.
by Benjamin H. Gallup.
S.B.
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Domurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233044.
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A numerical study of dilute suspensions based on a non-Newtonian matrix fluid and rigid spheroidal particles is performed. A Carreau fluid describes the non-Newtonian matrix. The special case of rigid spherical particles is considered. Here, a uniaxial elongational flow around a sphere is simulated and numerical homogenization is used to obtain the bulk viscosity of the dilute suspension for different applied rates of deformation and different thinning exponents. In the Newtonian regime the well-known Einstein result for the viscosity of a dilute suspension of rigid spherical particles is obtained. In the power-law regime it is found that the intrinsic viscosity depends only on the thinning exponent. Utilizing the simulation results a modification of the Carreau model for dilute suspensions with a non-Newtonian matrix fluid is proposed. To investigate the influence of the particle shape another numerical study is performed. In particular, different flows around spheroidal particles with different orientations are simulated and numerical homogenization is used to obtain the intrinsic viscosity of the suspension as function of applied rate of deformation, thinning exponent and aspect ratio. From the results it is possible to extract the rheological coefficients of the Lipscomb model. In the Newtonian regime the simulation results coincide with Lipscomb’s predictions. In the power-law regime the rheological coefficients depend strongly on the thinning exponent. Furthermore, simulation results indicate that the rheological coefficients additionally depend on the particle orientation in the non-linear regimeUne étude numérique sur des suspensions diluées à base d’un fluide non newtonien et de particules sphéroïdales rigides est réalisée. Le comportement de la matrice est décrit par un fluide de type Carreau. De particules sphériques et rigides est considéré en premier. Un écoulement en élongation uniaxiale autour d’une sphère est simulée. Ensuite, l’homogénéisation numérique est utilisée pour déterminer la viscosité apparente de la suspension pour différents taux de déformation et d’indices pseudoplastiques. Dans le domaine newtonien, le résultat d’Einstein donnant la viscosité d’une suspension diluée de particules sphériques et rigides est obtenu. Dans le régime en loi de puissance on constate que la viscosité intrinsèque dépend uniquement de l’indice pseudoplastique. Une autre étude numérique est effectuée pour investiguer l’influence de la forme des particules. Plusieurs écoulements autour d’une particule sphéroïdale sont simulés pour différentes orientations. Une homogénéisation numérique est ensuite utilisée pour obtenir la viscosité intrinsèque de la suspension en fonction du taux de déformation appliqué, de l’indice d’écoulement et du rapport de forme de la particule. A partir de ces résultats, il est possible d’exprimer les coefficients rhéologiques du modèle de Lipscomb. Dans le régime newtonien, les résultats coïncident avec les prédictions de Lipscomb. Dans le domaine en loi de puissance, les coefficients rhéologiques deviennent fortement dépendent de l’indice pseudoplastique. En outre, les résultats des simulations montrent que ces coefficients rhéologiques dépendent également de l’orientation des particules dans le régime non linéaire
Numerische Untersuchung zu verdünnten Suspensionen basierend auf einer nicht Newtonschen Matrixflüssigkeit und harten spheroidalen Partikeln wurde durchgeführt. Ein Carreau Fluid beschreibt die nicht Newtonsche Matrix. Zuerst wird der Spezialfall harter Kugeln betrachtet. Hierzu wird eine uniaxiale Dehnströmung um eine Kugel simuliert und numerische Homogenisierung wird verwendet um die effektive Viskosität der Suspension für verschieden aufgebrachte Deformationsgeschwindigkeiten und Verdünnungsexponenten zu bestimmen. Im Newtonschen Bereich wird die bekannte Lösung Einsteins für die Viskosität einer verdünnten Suspension harter Kugeln erhalten. Im power-law Bereich ist die intrinsische Viskosität einzig eine Funktion des Verdünnungsexponenten. Unter Nutzung der Simulationsergebnisse wird eine Modifikation des Carreau Modells vorgeschlagen. Um den Einfluss der Partikelform auf die nichtlinearen Eigenschaften zu untersuchen wird eine weitere numerische Simulationen durchgeführt. Dabei werden verschiedene Strömungen um spheroidale Partikel mit unterschiedlicher Orientierung simuliert und numerische Homogenisierung wird verwendet um die intrinsische Viskosität als Funktion der aufgebrachten Deformationsgeschwindigkeit, des Verdünnungsexponenten und des Partikelaspektverhältnisses zu bestimmen. Es ist möglich die rheologischen Parameter des Lipscomb Modells aus den Simulationsergebnissen zu bestimmen. Im Newtonschen Bereich stimmen die numerisch bestimmten Werte mit der Vorhersage Lipscomb‘s überein. Im power-law Bereich hängen die rheologischen Parameter stark vom Verdünnungsexponenten ab. Weiter kann man aus den Ergebnissen auf eine zusätzliche Abhängigkeit der rheologischen Parameter von der Partikelorientierung schließen
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Malkmus, Tobias [Verfasser], and Dietmar [Akademischer Betreuer] Kröner. "Fluid-structur-interaction simulations of non-Newtonian fluids interacting with thin elastic koiter shells." Freiburg : Universität, 2020. http://d-nb.info/1219851787/34.
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Anderson, Brian. "Development of a non-Newtonian latching device." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3855.
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Ouattara, Ziemihori. "Trainée et portance dans les fluides newtoniens et les fluides à seuil." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI032/document.
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Cette thèse expérimentale et numérique s’intéresse à l’écoulement à inertie négligeable d’un fluide newtonien et d’un fluide à seuil autour d’une plaque ou d’un cylindre en présence d’une paroi. Les efforts générés et les structures d’écoulement ont été particulièrement étudiés. Pour le fluide à seuil, l’étude est centrée sur le domaine des effets de seuil grands par rapport aux effets visqueux. Pour l’approche expérimentale, un dispositif a été conçu permettant de mesurer simultanément les forces de traînée et de portance en fonction de la vitesse et de la distance obstacle/paroi. Les fluides étudiés sont un sirop de glucose Newtonien et un gel de Carbopol considéré comme un fluide à seuil modèle. Ces matériaux ont été finement caractérisés du point de vue rhéologique. Des simulations numériques utilisant le modèle viscoplastique anélastique d’Herschel-Bulkley régularisé par le modèle de Papanastasiou ont été réalisées. Les résultats obtenus avec le fluide newtonien ont permis de valider l’installation expérimentale et l’approche numérique. Les effets de la contrainte seuil, de la distance paroi/obstacle, de la rhéofluidification, de l’angle d’inclinaison de la plaque sur les coefficients de traînée et de portance ont été examinés en détail. Le régime de lubrification a été étudié pour le cylindre expérimentalement et théoriquement. La morphologie de l’écoulement (zones rigides) et les grandeurs locales ont été montrées. Des solutions analytiques de la traînée et de la portance ont été proposées. Les comparaisons entre les résultats expérimentaux et numériques ainsi qu’avec les solutions issues de la plasticité de la mécanique des sols sont analysées. Les écarts sont discutés en termes d’influence de l’élasticité et de plasticité du fluide à seuilThis experimental and numerical thesis deals with the creeping flow of a Newtonian fluid and a yield stress fluid around a plate or a cylinder in the presence of a wall. The generated forces and the flow structures have been particularly studied. The study focuses for the yield stress fluid on large yield stress effects compared to the viscous effects. For the experimental approach, a device has been designed to measure simultaneously the drag and lift forces as a function of velocity and obstacle / wall distance. The fluids studied are a Newtonian glucose syrup and a Carbopol gel considered as a yield stress fluid model. These materials have been finely characterized from the rheological point of view. Numerical simulations using the Herschel-Bulkley anelastic viscoplastic model regularized by the Papanastasiou model were carried out. The results obtained with the Newtonian fluid allowed to validate the experimental set-up and the numerical approach. The effects of the yield stress, the wall / obstacle distance, the power law index and the inclined plate on the drag and lift coefficients were carefully examined. The lubrication regime has been studied for the cylinder both experimentally and theoretically. The morphology of the flow (rigid zones) and the local field quantities have been shown. Analytical solutions of drag and lift have been proposed. Comparisons between the experimental and numerical results as well as the solutions resulting from the plasticity of soil mechanics are analyzed. Deviations are discussed in terms of the elasticity and plasticity influence of the yield stress fluid
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Yildirim, B. Gazi. "A global preconditioning method for the Euler equations." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-07152003-164237.
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Ramos, Anilzabel Costa dos. "Modelos unidimensionais para fluidos Newtonianos e Newtonianos generalizados." Master's thesis, Universidade de Évora, 2021. http://hdl.handle.net/10174/29820.
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Este trabalho de dissertação tem como objectivo o desenvolvimento e estudo de modelos
unidimensionais para o escoamento de um fluido com base na teoria de Cosserat,
também conhecida pela teoria dos directores. A base desta teoria relativa `a dinâmica
dos fluidos ´e semelhante `a que se usa no estudo de vigas em Mecânica dos Sólidos, ver
por exemplo os trabalhos [4, 5]. Um modelo tridimensional associado ao escoamento
de fluido Newtoniano, ou uma sua generalização onde a viscosidade depende da taxa
de cisalhamento, tal dependência do tipo lei de potência, ´e um modelo complexo para
estudar em termos de optimização computacional, o que em muitas situações relevantes
torna-se inviável. Para simplificar o modelo tridimensional e como alternativa aos
modelos clássicos unidimensionais, usaremos a teoria de Cosserat relacionada com a
dinâmica dos fluidos para aproximar o campo de velocidades e assim obter um sistema
unidimensional constituído por uma equação diferencial ordinária ou parcial, dependendo
apenas do tempo e de uma única variável de espaço. A partir deste sistema
de redução, obtemos uma equação para o gradiente de pressão média dependendo do
caudal volumétrico, número de Womersley e do ´ındice de fluxo no caso de um fluido
Newtoniano generalizado, sobre uma secção finita da geometria do domínio em estudo.
No nosso trabalho a geometria em estudo vai ser um tubo de secção circular com raio
constante e não constante ao longo do escoamento simétrico relativo ao eixo de simetria.
A atenção é focada em algumas simulações numéricas para gradiente de pressão
média constante e não constante usando um método Runge-Kutta e na análise de fluxos
perturbados. Em particular, para certos dados específicos, podemos obter informações
sobre o caudal volumétrico e, consequentemente, podemos ilustrar o campo de velocidade
tridimensional na secção transversal circular do tubo. Além disso, comparamos a
solução exata tridimensional estacionária com a solução unidimensional correspondente
obtida pela teoria de Cosserat. Este trabalho de dissertação tem por base os trabalhos
[1, 2, 3]; Abstract:
One-dimensional Models for Newtonian and Generalized Newtonian
Fluids
This dissertation work aims to develop and study one-dimensional models for the flow
of a fluid based on the Cosserat theory, also known by the theory of directors. The basis
of this theory on fluid dynamics is similar to that used in the study of beams in Solid
Mechanics, see for example the works [4, 5]. A three-dimensional model associated
with the flow of Newtonian fluid, or a generalization where viscosity depends on the
shear rate, such dependence on the power law type, is a complex model to study in
terms of computational optimization, which in many relevant situations becomes if
not viable. To simplify the three-dimensional model and as an alternative to classic
one-dimensional models, we will use the Cosserat theory related to fluid dynamics to
approximate the velocity field and thus obtain a one-dimensional system consisting of
an ordinary or partial differential equation, depending only on time and of a single
space variable. From this reduction system, we obtain an equation for the average
pressure gradient depending on the volumetric flow, Womersley number and the flow
index in the case of a generalized Newtonian fluid, over a finite section of the geometry
of the domain under study. In our work the geometry under study will be a tube
of circular section with constant and non-constant radius along the symmetrical flow
relative to the axis of symmetry. Attention is focused on some numerical simulations
for constant and non-constant mean pressure gradient using a Runge-Kutta method
and on the analysis of disturbed flows. In particular, for certain specific data, we
can obtain information on the volumetric flow and, consequently, we can illustrate the
three-dimensional velocity field in the circular cross section of the tube. In addition, we
compared the exact stationary three-dimensional solution with the corresponding onedimensional
solution obtained by Cosserat’s theory. This dissertation work is based on
the works [1, 2, 3].
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Kabamba, Batthe Matanda. "Evaluation of centrifugal pump performance derating procedures for non-Newtonian slurries." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/2170.
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Thesis (MTech(Civil Engineering))--Cape Peninsula University of Technology, 2006.The performance of a centrifugal pump is altered for slurry or viscous materials (Stepanoff, 1969) and this needs to be accounted for. Usually, the suitable selection and evaluation of centrifugal pumps is based only on water pump performance curves supplied by the pump manufacturer (Wilson, Addie, Sellgren & Clift, 1997). In 1984 Walker and Goulas conducted a number of pump performance tests with kaolin clay slurries and coal slurries on a Warman 4/3 AH horizontal slurry pump and a Hazleton 3-inch B CTL horizontal pump (Walker and Goulas, 1984). Walker and Goulas have analysed the test data and correlated the performance derating both at the best efficiency flow rate (BEP) and at 10% of the best efficiency flow rate (0.1 BEP) to the modified pump Reynolds number (NRep). They have noticed that the head and the efficiency reduction ratio decreased for the pump Reynolds number less then 10⁶. Furthermore, Walker and Goulas obtained a reasonably good agreement (± 5%) between pump test data for non-Newtonian materials and pump performance prediction using the Hydraulics Institute chart. Sery and Slatter (2002) have investigated pump deration for non-Newtonian yield pseudoplastic materials. The NRep was calculated using the Bingham plastic viscosity (µp). Results have shown good agreement with regard to head and efficiency reduction ratios in comparison with previous work. However, Sery and Slatter's pump performance correlation using the HI chart did not reach the same conclusion. Error margin of ± 20% and ± 10% were found for head and efficiency respectively. This study is an attempt to reconcile the differences between Walker and Goulas (1984) and Sery and Slatter (2002) and extend the evaluation of these derating methods to pseudoplastic materials. The test work was conducted in the Flow Process Research Centre laboratory of the Cape Peninsula University of Technology using two centrifugal pumps; a Warman 6/4 and a GrW 4/3. The materials used were water, CMC solution bentonite and kaolin suspension at different concentrations (7% and 9% by weight for bentonite; 5%, 6% and 7% by weight for CMC; 17%, 19% and 21% by volume for kaolin).
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Guneratne, Julie Clare. "High Reynolds number flow in a collapsible channel." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340767.
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Lockett, Timothy James. "Numerical simulation of inelastic non-Newtonian fluid flows in annuli." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8422.
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Fullerton, Gary Henry. "Investigation of non-Newtonian fluid turbulence via direct numerical simulation." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/13861.
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It has been over 50 years since Toms [B.A. Toms, Proc. 1st Int. Congr. Rheol., Sec. II, 135, North Holland (1949)] discovered that adding small quantities of long-chain polymer to turbulent pipe flow could drastically reduce the amount of turbulent drag. Since then a substantial amount of research has gone into examining dilute polymer solutions and their turbulent drag reducing properties, yet the precise mechanism by which the polymers interact with the turbulence to produce this affect is still unclear. From a theoretical standpoint, the difficulty lies in the analysis of accurate models of the fluid dynamics. The combination of the complex mathematical description required for turbulence and the intricate constitutive equations of polymer motion poses significant problems. However, recent developments in computing have resulted in machines powerful enough to simulate such flows using direct numerical simulation (DNS); a technique whereby all the important scales of turbulent fluid motion are fully resolved using an algorithm derived from the full momentum conservation equations. DNS has been successfully employed in previous studies of dilute polymer solutions in computational domains similar to experimental apparatus such as pipe flow [J. M. J. den Toonder, M. A. Hulsen, G. D. C. Kuiken and F. T. M. Nieuwstadt, J. Fluid Mech., 337, 193 (1997)] and channel flow, [R. Sureshkumar, A. N. Beris and R. A. Handler, Phys. Fluids, 9(3), 743 (1996)]. It was our aim to identify the changes within the turbulent dynamics produced by the presence of polymers in homogeneous isotropic turbulence - without an dependence on solid boundary conditions. We decided to simulate our solutions within a infinitely repeating cube subject to periodic boundary conditions, a well established technique for Newtonian fluids. In this thesis we examine a range of spectral measures and integral parameters for various non-Newtonian fluid models in statistically stationary homogeneous isotropic turbulence and compare them to an equivalent Newtonian flow using DNS. We begin by outlining the general theory of homogeneous isotropic non-Newtonian turbulence in the Fourier space domain. We then demonstrate how the general non-Newtonian momentum conservation equations are adapted for use in our DNS. This is followed by a literature review of turbulent drag reduction by long-chain polymer additives. The remainder of the thesis is concerned with the new work. We outline the four non-Newtonian fluid models we applied and present the results obtained from the DNS calculations. Each model embodies a particular characteristic of polymer solutions. The first is of our own construction and is based on the ability of polymers to increase the viscosity of the solution at small scales. Second, we simulate the nonlinear model of McComb [W. D. McComb, Int. J. Engng. Sci., 14, 239 (1976)] where the stress exhibits a nonlinear dependence on the rate of strain. For both of these we were able to obtain an analytical expression for the energy spectra and compared these to the DNS results. The third model is the viscous anisotropic model of den Toonder et al. (see above reference) which introduces a directional element based on the orientation of the polymers in the flow, by assuming they are of constant length and align with the instantaneous velocity. Finally we model a fully coupled FENE-P fluid [L. E. Wedgwood and R. B. Bird, Ind. Eng. Chem. Res., 27, 1313 (1988)] in which the polymers are finitely extensible, elastic and have their own equation of motion giving their orientation. In this way we have identified changes within the structure of turbulence itself which may be related to the drag reduction phenomenon.
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Havard, 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.
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In this thesis, a theoretical investigation is undertaken into fluid and mixing flows generated by various geometries for Newtonian and non-Newtonian fluids, on both sequential and parallel computer systems. The thesis begins by giving the necessary background to the mixing process and a summary of the fundamental characteristics of parallel architecture machines. This is followed by a literature review which covers accomplished work in mixing flows, numerical methods employed to simulate fluid mechanics problems and also a review of relevant parallel algorithms. Next, an overview is given of the numerical methods that have been reviewed, discussing the advantages and disadvantages of the different methods. In the first section of the work the implementation of the primitive variable finite element method to solve a simple two dimensional fluid flow problem is studied. For the same geometry colour band mixing is also investigated. Further investigational work is undertaken into the flows generated by various rotors for both Newtonian and non-Newtonian fluids. An extended version of the primitive variable formulation is employed, colour band mixing is also carried out on two of these geometries. The latter work is carried out on a parallel architecture machine. The design specifications of a parallel algorithm for a MIMD system are discussed, with particular emphasis placed on frontal and multifrontal methods. This is followed by an explanation of the implementation of the proposed parallel algorithm, applied to the same fluid flow problems as considered earlier and a discussion of the efficiency of the system is given. Finally, a discussion of the conclusions of the entire accomplished work is presented. A number of suggestions for future work are also given. Three published papers relating to the work carried out on the transputer networks are included in the appendices.
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Mandal, Anirban. "Computational Modeling of Non-Newtonian Fluid Flow in Simplex Atomizer." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1202997834.
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Jeon, Jaewoo. "Displacing visco plastic fluid with Newtonian fluid in a vertical circular pipe with buoyancy effects." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/60318.
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In this thesis, displacement flows in a vertical pipe are studied when Newtonian fluids displace visco-plastic fluids. The density combinations between displacing and displaced fluids are varied from density unstable through iso-density to density stable, and captured dimensionlessly using Atwood numbers. In density unstable cases, three flow regimes are classified: central, mixed/turbulent and asymmetric regimes. These regimes are partially classified by a buoyancy parameter. However, we found that the buoyancy parameter has a limit in classifying the flow regimes. Once the flow enters the turbulent regime, spread of the dispersive mixed region is characterized by fitting the mean concentration changes to the solution of an 1D linear advection diffusion equation, i.e., turbulent diffusivity (or dispersivity) dominates in this regime. In iso-density cases, all flows are classified in central regime but the shapes of static layers are classified as: smooth, wavy and corrugated. We found that Re, Newtonian Reynolds number, differentiates the static layer shapes. Transitional Reynolds numbers are identified as Re = 345 for corrugated to wavy and Re = 1000 for wavy to smooth. The transitional Re for turbulent regime is identified at around 4000. Lastly, we observed that viscous fingering is common in density stable cases. Viscous fingering is observed for large effective viscosity, ratio of a viscoplastic fluid to a Newtonian fluid, and a ratio of shear stress to a yield stress of a displaced fluid ratio is small, and starts from an elongated thin layer finger. In the regime, the wall shear stress is too small to yield the visco-plastic fluid from the wall and the mobility of the displacing fluid is relatively high, so it seeks a way to channel though the visco-plastic fluid. The transitional Re for mixed/turbulent regime was not found within our experimental range. The displacement efficiency, described in the ratio of a front velocity to a mean velocity in density stable cases increases by approximately 15%, compared to density unstable and iso-density. Density unstable experiments can have better efficiency than iso-density experiments due to entering mixing regime in lower Reynolds numbers. However, the differences in the efficiency are generally small.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Azevedo, Cardoso Ivan. "Lois d'échange lors du refroidissement d'un fluide non newtonien thermo-dépendant." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL045N.
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Le présent travail se propose d'étudier expérimentalement et numériquement les lois de l'écoulement et du transfert de chaleur pour des fluides non-newtoniens thermo-dépendants en écoulement laminaire dans une conduite cylindrique, refroidie à densité de flux de chaleur et à températures de paroi variables. Nous nous intéressons aux fluides pseudoplastiques dont le comportement peut être modifié par la loi de puissance d'Ostwald. On étudie l'incidence d'un champ thermique impose sur la distribution de vitesse et sur les lois de transfert de chaleur qui en résultent. Nous proposons une corrélation qui tient compte de la thermo-dépendance. En outre, nous proposons un modèle de calcul de l'épaisseur de la couche de glace pour les régions ou se produit la congélation
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Livescu, Silviu. "Mathematical and numerical modeling of coating flows." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.48 Mb., 279 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3221057.
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Alseamr, Nisreen. "A Theoretical Simulation of the Settling of Proppants in a Hydraulic Fracturing Process." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4272.
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Hydraulic fracturing is a process for the extraction of hydrocarbons from underground formations. It involves pumping a specialized fluid into the wellbore under high pressures to form and support fractures in the rock. Fracturing stimulates the well to increase the production of oil and the natural gas which are the pillars of the energy economy. Key to this process is the use of proppants, which are solid materials used to keep the fractures open. Understanding the transport of proppant particles through a fluid is important to improve the efficiency and reduce environmental impact of fracturing. An increase of the settling velocity for instance, will impede the hydraulic fracturing process by reducing well productivity, or necessitate use of chemical additives. This thesis presents a theoretical investigation of the settling velocity of proppant particles. The effect of different parameters on the settling velocity were studied by manipulating the main factors that can influence particle transport. These include size of the particle (300 μm- 2000 μm), sphericity, density (1200 kg/m3-3500 kg/m3) and concentration. These typical values were obtained from commercially available proppants currently used in industry. Various correlations were investigated, assuming the carrier (fracturing) fluid to be an ideal Newtonian and as a power law (non-Newtonian) fluid. This will help predict the settling velocity for proppant particles in order to increase well productivity, and improve hydraulic fracturing efficiency. The models show that changing the carrier fluid viscosity and particle properties such as diameter, density, sphericity, and concentration leads to a significant change in the proppant settling velocity. For instance, reduction in particle size, density, and sphericity tend to reduce the settling velocity, while increasing the concentration of the particles and the fluid viscosity reduce the settling velocity.
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Meuric, Olivier Francois Joseph. "Numerical modelling of fluid flow in drilling processes." Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267227.
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Goshawk, Jeffrey Alan. "Enhancement of the drainage of non-Newtonian liquid films by oscillation." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333685.
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ALEXANDRE, BERNARDO BASTOS. "FLOW OF NON-NEWTONIAN FLUID IN ANNULAR SPACE WITH VARYING ECCENTRICITY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15404@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Na perfuração de poços é necessária a utilização de um fluido de perfuração que apresenta diversas funções. Esse fluido retorna para superfície pelo anular formado entre a coluna de perfuração e o poço, sendo fundamental a correta previsão desse escoamento. Uma análise dessa situação é extremamente complexa, uma vez que o fluido tem comportamento não Newtoniano, a coluna de perfuração apresenta rotação e é excêntrica, sendo que a excentricidade pode não ser constante ao longo do poço. Os trabalhos disponíveis na literatura estudam os efeitos da rotação e do comportamento do fluido, mas consideram a excentricidade constante. No presente trabalho as equações de conservação de quantidade de movimento e massa que governam o escoamento serão simplificadas utilizando a teoria da lubrificação, resultando em um problema com solução mais simples e baixo custo computacional. Modelos similares desprezam o efeito de curvatura, sendo válidos somente para razões de raio próximas da unidade. A formulação desenvolvida considera todos os termos, dando origem a uma teoria de lubrificação em coordenadas cilíndricas. A simplificação resulta em uma equação diferencial para o campo de pressão. O comportamento do fluido será avaliado através do método da Viscosidade Newtoniana Equivalente. A partir da solução é possível avaliar o perfil de velocidade que varia ao longo da coordenada axial. Os resultados foram validados a partir de soluções disponíveis na literatura (excentricidade constante). Além disso, os efeitos da variação da excentricidade no fator de atrito foram estudados e a existência de escoamento azimutal mesmo sem rotação da coluna foi observada.
In drilling operation of wells it is necessary to use a drilling fluid that has many functions. Flow in the annular space between the drill pipe and the well occurs during the return to the surface. The correction prediction of this flow is important and the complete study is very complex: the fluid has non-Newtonian behavior, the drill pipe is rotating and a varying eccentricity of the drill pipe is possible. Previous analyses in the literature study effects of the rotation and the rheological behavior of the fluid, but consider a constant eccentricity along the axial coordinate. In this work, the equations of momentum and mass conservation that govern the flow is simplified by the lubrication approximation and a twodimensional problem that has simple solution and lower computational cost is obtained. Similar models available neglect the curvature and are only accurate for radius ratio close to one. The formulation developed in this work considers all terms, leading to a lubrication approximation in cylindrical coordinates. The consequence of this approximation is a differential equation for the pressure field. The rheological behavior of the fluid will be evaluated using the method of Equivalent Newtonian Viscosity. With pressure field is possible to determinate the velocity that varies along axial coordinate. The accuracy of the model was analyzed using solutions available in literature (constant eccentricity case). The results show the effects of the variation of the eccentricity on the friction factor and the existence of azimuthal flow even without rotation of the drill pipe.
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CARVALHO, MARCIO DA SILVEIRA. "HEAT TRANSFER IN NON-NEWTONIAN FLUID FLOW THROUGH AN ABRUPT HIRING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1991. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19071@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO trabalho analisa a transferência de calor no escoamento de fluidos não-newtonianos através de uma contração abrupta circular de razão 4:1, com temperatura prescrita nas paredes sólidas. O escoamento de fluidos elásticos nesta geometria apresenta uma região de recirculação bem maior que no caso de fluidos Newtonianos. Esta alteração no padrão do escoamento altera significativamente o processo de transferência de calor. O escoamento representa uma boa modelagem do processo de extrusão de líquidos poliméricos. Resolvem-se as equações de conservação de momentum e energia desacopladamente, já que foi adotadas a hipótese de não variação das propriedades do fluido com a temperatura. A relação tensão – taxa de deformação foi feita através de dois modelos constitutivos, Newtoniano generalizado e Maxwell convectado. A hipótese de escoamento lento não foi adotada, como é usualmente feito na literatura da área. Deste modo, analisa-se separadamente a influencia dos efeitos elásticos e inerciais. As equações diferenciais foram integradas numericamente pelo método dos volumes finitos e o aclopamento velocidade\ pressão foi feito através do algoritmo SIMPLE. Pelos resultados obtidos, observa-se a importância da modelagem não newtoniana e da inclusão dos termos inerciais no estudo do escoamento e da transferência de calor no processo de extrusão de polímeros.
It is well known that the flow of a non-Newtonian fluid through a sudden contraction exhibits a vortex in the corner region bigger than the one observed in the corresponding flow of a Newtonian Fluid. This change of pattern of the flow affects significantly the heat transfer at the wall. It was investigated the case og a a 4:1 circular contraction, with uniform temperature distrubuition at the solid walls. This problem represents a first approach for the analysis of the polymeric liquids extrusion process. The flow and temperature field have been obtained from the numerical integration of the conservation equations. To account for the flow dependence of the stress tensor, a generalized Newtonian model and a convected Maxwell model have been employed. The creeping flow hypothesis has not been adopted, so it was possible to analyse the elastic effects and the inertial effects separately. The nuemerical solution have been obtained via a finite-volume method. The results show the importance of the non-Newtonian modeling and of the inclusion of inertial terms in the study of the flow and beat transfer in the polymeric liquids extrusion process.
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Zografos, Konstantinos. "Intelligent design of microfluidic components for Newtonian and complex fluid systems." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28038.
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Interest in microfluidics has increased dramatically in recent years, with applications spanning a wide range of fields. However, despite several advances, design of microfluidic devices still relies largely on trial-and-error. This thesis aims to go beyond this approach in favour of a rational design of microfluidic devices based on theoretical and numerical design rules and algorithms. More specifically, this research focuses on understanding and controlling fluid dynamics in applications involving complex non-Newtonian fluids in shear and extensional flows. Biomimetic principles and shape optimisation methods are employed to propose new designs for single-phase fluid flow. Furthermore, the singlephase numerical solver is extended to cope with two-phase systems, thus paving the way for new applications of these techniques. Focusing on shear-flows, a biomimetic principle appropriate for fully developed flows has been extended here to be applicable for non-Newtonian fluids, described by the power-law constitutive relationship. The derivation of the principle leads to a biomimetic rule that provides the appropriate dimensions for designing customised microfluidic bifurcating networks, able to generate specific wall shear-stress gradients along consecutive generations. A range of power-law fluids is examined numerically demonstrating great agreement with theoretical predictions. In terms of extensional flow, a range of shapes are proposed for designing microfluidic channels for studies related to the response of complex fluid systems under homogeneous strain-rate. Optimisation techniques are employed for finding the appropriate shapes to generate homogeneous extensional flows along the flow centreline of singlestream (contraction-expansion channels) and the multi-stream designs (T-channels and flow focusing devices). The optimised geometries proposed exhibit enhanced performance compared to well defined geometrical shapes. The in-house single phase solver used in all numerical studies is upgraded here in order to solve numerically 3D-problems related to two-phase systems described by the Phase Field method. Here, the code is validated for 2D-problems only, using a range of test-cases demonstrating a very good quantitative agreement. Keywords: Non-Newtonian fluids, Shear-thinning and shear-thickening behaviour, Bifurcating networks, Biomimetics, Optimisation, Extensional flows, Two-phase systems.
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Keegan, Fiona. "Experimental investigation into non-Newtonian fluid flow through gradual contraction geometries." Thesis, University of Liverpool, 2009. http://livrepository.liverpool.ac.uk/1293/.
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This thesis presents the results of an investigation into the flow of several non- Newtonian fluids through two curved gradual planar contractions (contraction ratios 8:1 and 4:1). The objectives were to determine whether a newly discovered effect (velocity overshoots were observed in the flow of a 0.05% polyacrylamide solution close to the sidewalls of a gradual contraction followed by a sudden expansion by Poole et al., 2005) could be reproduced in the absence of the expansion, learn more about the phenomenon and to provide a comprehensive set of experimental results for numerical modellers to compare their results to. The fluids investigated were a Newtonian control fluid (a glycerine-water mixture), four concentrations of polyacrylamide (PAA), varying from the ‘dilute’ range to the ‘semi-dilute’ range and two concentrations of xanthan gum (XG), both in the ‘semi- dilute’ range. All fluids were characterised using shear rheology techniques and where possible extensional rheology measurements were also undertaken. The fluid properties determined from this characterisation were used to estimate various non- dimensional numbers such as the Reynolds and Deborah numbers, which can then be used to characterise the flow. The flow under investigation was the flow through a gradual contraction section. Two smooth curved planar gradual contractions were used with contraction ratios of 8:1 and 4:1. The upstream internal duct dimensions were 80mm by 80mm in both cases and the downstream internal duct dimensions were 80mm by 10mm for the 8:1 contraction and 80mm by 20mm for the 4:1 contraction. Polymer degradation within the test rig was assessed and the maximum time that the solutions could be reliably used was found to be six hours. The fluid velocity was measured at discrete locations within the flow using laser Doppler anemometry (LDA), which is a non-intrusive flow measurement technique. Measurements were taken across the XZ-centreplane (side to side) and in some cases across the XY-centreplane (top to bottom). The flow of the Newtonian control fluid was as expected with the flow flattening into the ‘top hat’ shape usually observed in Newtonian flow through a gradual contraction (as utilised in wind tunnel design for example). The flows of 0.01% PAA (‘dilute’) and 0.07% XG (‘semi-dilute’) also flattened as the flow progressed through the 8:1 contraction as the Deborah numbers in these flows were very low. Velocity overshoots close to the plane sidewalls were observed in both the 0.03% and 0.05% PAA solutions through the 8:1 and 4:1 contractions. The overshoots through both contractions seemed to be influenced most by the Deborah number (i.e. the extensional properties of the flow and fluid). Velocity overshoots were observed in the 0.3% PAA solution through both contractions but they were different in shape to those seen at the lower concentrations. The overshoots were closer to the centre of the flow growing into one large ‘overshoot’ at the end of the contraction. This investigation showed that the velocity overshoots can be reproduced in both the 8:1 and 4:1 gradual contraction in several concentrations of PAA providing the right parameters are met (i.e. fluid properties, flow rate etc.). Good quality sets of data have been produced, which can be used in the future by researchers interested in numerical modelling of non-Newtonian fluid flows through similar contractions.
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Vieira, Adriana Silveira [UNESP]. "Um panorama sobre roll waves em escoamentos laminares e turbulentos com superfície livre." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/88890.
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Os escoamentos na superfície livre que se processam sobre forte declividade podem desenvolver instabilidades ao cabo de tempo finito. Tais instabilidades aparecem sob formas de ondas tipo “hydraulic jumps” bem espaçados e são denominadas Roll Waves. Estas ondas, longas e periódicas, podem ser contínuas ou descontínuas; contínuas em problema Shallow Water viscoso e descontínuas para o caso não viscoso. Tal fenômeno pode ser observado tanto em escoamentos naturais como em canais artificiais e vertedouros de barragens. Tratando-se de escoamento de Fluidos não newtonianos, tal fenômeno pode ser visto facilmente em lavas torrenciais, avalanchas ou “debris flows”. Nesta dissertação foram analisados matematicamente e numericamente o comportamento e as condições de existência para a formação de Roll Waves em escoamentos laminares e turbulentos. Em escoamentos turbulentos toma-se como referência os trabalhos realizados por Maciel (2001) numa reologia Binghamiana. Para escoamentos laminares, cita-se o trabalho de Mei (1994) em uma reologia tipo Power Law. No plano numérico, para escoamentos turbulentos, foram utilizadas rotinas do MATLAB® versão 6.5 e, para escoamentos laminares, rotinas em FORTRAN 90; onde pôde-se analisar e comparar resultados para diversas reologias. O foco desta dissertação foi tratar o problema Roll Waves como uma instabilidade na vizinhança do regime uniforme para Fluidos não newtonianos, em regimes turbulentos e laminares. A reologia tratada e representativa de diversos escoamentos na natureza foi a de Herschel Bulkley. A partir desta dissertação deixa-se, como perspectiva futura, um estudo mais aprofundado sob formação de ondas em fluidos hiperconcentrados tipo Herschel Bulkley com abordagem experimental a fim de validar resultados apontados nesta pesquisa.
Flows that happen over strong slope with free surface can develop instabilities after some finite time. Such wave shaped instabilities appear in the flow and are of the type “hydraulic jumps” well spaced and they are called Roll Waves. Those waves are long and periodic, continuous or discontinuous, continuous in viscous Shallow Water problems, and discontinuous for the inviscid case. Roll Waves are uncommon in natural flows, but they are common in man made channels and dams spillway. For flows of non Newtonian fluids such phenomenon can be seen easily in lava torrent, avalanche and debris flow. In this work it were mathematically and numerically analyzed the behavior and the existence conditions for the generation of Roll Waves within laminar and turbulent flows. For turbulent flows it is taken as reference the works done by Maciel (2001) dealing with a Bingham rheology. For laminar flows the reference is the work done by Mei (1994) using a Power Law rheology. Numerically, for turbulent flows it were used MATLAB® 6.5 procedures and for laminar flows FORTRAN 90 procedures were developed. Using these reference procedures it was obtained compared and analyzed results for several rheologies. This work left as future perspective a deeper study about the generation of waves in hipper concentrated fluids such as Herschel Bulkley fluid, with an experimental approach aiming to validate results produced. The focus of this work was to treat the so called Roll Waves problem as an instability in the vicinity of the uniform flow regime for non Newtonian fluids under laminar and turbulent flow regimes. The Herschel Bulkley rheology that was treated in this work is representative of several flows that happen in nature.
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Tshilumbu, Nsenda Ngenda. "The effect of type and concentration of surfactant on stability and rheological properties of explosive emulsions." Thesis, [S.l. : s.n.], 2009. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1063&context=td_cput.
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Pachmann, Sydney. "Swimming in slime." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1503.
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The purpose of this thesis is to study the problem of a low Reynolds number
swimmer that is in very close proximity to a wall or solid boundary in a non-
Newtonian fluid. We assume that it moves by propagating waves down its length
in one direction, creating a thrust and therefore propelling it in the opposite
direction. We model the swimmer as an infinite, inextensible waving sheet.
We consider two main cases of this swimming sheet problem. In the first
case, the type of wave being propagated down the length of the swimmer is
specified. We compare the swimming speeds of viscoelastic shear thinning,
shear thickening and Newtonian fluids for a fixed propagating wave speed. We
then compare the swimming speeds of these same fluids for a fixed rate of work
per wavelength. In the latter situation, we find that a shear thinning fluid
always yields the fastest swimming speed regardless of the amplitude of the
propagating waves. We conclude that a shear thinning fluid is optimal for the
swimmer. Analytical results are obtained for various limiting cases. Next, we
consider the problem with a Bingham fluid. Yield surfaces and flow profiles are
obtained.
In the second case, the forcing along the length of the swimmer is specified,
but the shape of the swimmer is unknown. First, we solve this problem for a
Newtonian fluid. Large amplitude forcing yields a swimmer shape that has a
plateau region following by a large spike region. It is found that there exists
an optimal forcing that will yield a maximum swimming speed. Next, we solve
the problem for moderate forcing amplitudes for viscoelastic shear thickening
and shear thinning fluids. For a given forcing, it is found that a shear thinning
fluid yields the fastest swimming speed when compared to a shear thickening
fluid and a Newtonian fluid. The difference in swimming speeds decreases as
the bending stiffness of the swimmer increases.
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Malek, Alaeddin. "Numerical spectral solution of elliptic partial differential equations using domain decomposition techniques." Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241798.
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Thorvaldsen, Gary Sven. "The effect of the particle size distribution on non-Newtonian turbulent slurry flow in pipes." Thesis, Cape Technikon, 1996. http://hdl.handle.net/20.500.11838/896.
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Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town,1996The handling of solid-liquid suspensions is an important concern within the chemical and processing industries and many theoretical models have been proposed to try and explain and predict turbulent flow behaviour. However, the prediction of turbulent flow from only the viscous properties of non-Newtonian suspensions has over the years been questioned by researchers. This thesis considers theoretical models well established in the literature and the Slatter model, which uses both the rheology of the suspension and the particle size distribution of the solids. These models are used to analyze the experimental data and the effect that particle size and the particle size distribution has on turbulent flow behaviour. The literature concerning the rheological fundamentals relevant to fluid flow in pipes has been examined. The Newtonian turbulent flow model as well as the non-Newtonian models of Dodge & Metzner, Torrance, Kemblowski & Kolodziejski, Wilson & Thomas and Slatter have been reviewed. Test work was conducted at the University of Cape Town's Hydrotransport Research Laboratory using a pumped recirculating pipe test rig. The test apparatus has been fully described and calibration and test procedures to enable collecting of accurate pipeline data have been presented. Three slurries were used in test work namely kaolin clay, mixture I (kaolin clay and rock flour) and mixture 2 (kaolin clay, rock flour and sand) with ad,s particle size ranging from 24/Lm to 170/Lm. The yield pseudoplastic model has been used to model and predict the laminar flow of the suspensions that were tested and the meth9J adopted by Neill (1988) has been used to determine the rheological constants. The pipeline test results have been presented as pseudoshear diagrams together with the theoretical model lines providing a visual appraisal of the performance of each model. The Slatter model predicts the test data best with the other theoretical models that were considered tending to under predict the head loss. The reason the Slatter model performs better than the other theoretical models is because this model can account for the wall roughness and particle roughness effect. Evidence to support this statement has been presented. This thesis highlights the fact that the particle size distribution is a vitally important property of the suspension and that it does influence turbulent flow behaviour. It shows that turbulence modelling using the particle roughness effect (eg Slatter, 1994) is valid and can be adopted for non-Newtonian slurries. It is concluded that the particle size distribution must be used to determine the particle roughness effect and this effect must be incorporated in the turbulent flow analysis of non-Newtonian slurries.
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Boukanga, Noel Rupert Thierry. "Three dimensional modelling of generalized Newtonian fluids in domains including obstructions." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6936.
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Three dimensional flow regimes are encountered in many types of industrial flow processes such as filtration, mixing, reaction engineering, polymerization and polymer forming as well as environmental systems. Thus, the analyses of phenomena involved fluid flow are of great importance and have been subject of numerous ongoing research projects. The analysis of these important phenomena can be conducted in laboratory through experiments or simply by using the emerging computational fluid dynamics (CFD) techniques. But when dealing with three dimensional fluid flow problems, the complexities encountered make the analysis via the traditional experimental techniques a daunting task. For this reason, researchers often prefer to use the CFD techniques which with some care taken, often produce accurate and stable results while maintaining cost as low as possible. Many CFD codes have been developed and tested in the past decades and the results have been successful and thus encouraging researchers to develop new codes and/or improve existing codes for the solutions of real world problems. In this present project, CFD techniques are used to simulate the fluid flow phenomena of interest by solving the flow governing equations numerically through the use of a personal computer. The aim of this present research is to develop a robust and reliable technique which includes a novel aspect for the solution of three dimensional generalized Newtonian fluids in domains including obstructions, and this must be done bearing in mind that both accuracy and cost efficiency have to be achieved. To this end, the finite element method (FEM) is chosen as the CFD computational method. There are many existing FEM techniques namely the streamline upwind Petrov-Galerkin methods, the streamline diffusion methods, the Taylor-Galerkin methods, among others. But after a thorough analysis of the physical conditions (geometries, governing equations, boundary conditions, assumptions …) of the fluid flow problems to be solve in this project, the appropriate scheme chosen is the UVWP family of the mixed finite element methods. It is scheme originally developed to solve two dimensional fluid flow problems but since the scheme produced accurate and stable results for two dimensional problems, then attempt is made in this present study to develop a new version of the UVWP scheme for the numerical analysis of three dimensional fluid flow problems. But, after some initial results obtained using the developed three dimensional scheme, investigations were made during the course of this study on how to speed up solutions' convergence without affecting the cost efficiency of the scheme. The outcomes of these investigations yield to the development of a novel scheme named the modified three dimensional UVWP scheme. Thus a computer model based on these two numerical schemes (UVWP and the Modified UVWP) is developed, tested, and validated through some benchmark problems, and then the model is used to solve some complicated tests problems in this study. Results obtained are accurate, and stable, moreover, the cost efficiency of the computer model must be mentioned because all the simulations carried out are done using a simple personal computer.
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Thovert, Jean-François. "Phenomenes de transfert dans les milieux poreux fractals : l'empilement apollonien." Paris 6, 1987. http://www.theses.fr/1987PA066217.
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On definit un modele bidimensionnel de milieu poreux fractal. Ce modele utilise des empilements quasi-osculateurs de disques, eventuellement anisotropes et aleatoires. Description analytique complete des proprietes de transport par conduction. Etude numerique de la permeabilite de l'empilement vis-a-vis des fluides newtoniens et non newtoniens en loi puissance
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Vieira, Adriana Silveira. "Um panorama sobre roll waves em escoamentos laminares e turbulentos com superfície livre /." Ilha Solteira : [s.n.], 2007. http://hdl.handle.net/11449/88890.
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Orientador: Geraldo de Freitas MacielBanca: André Luiz Seixlack
Banca: Luís Miguel Chagas da Costa Gil
Resumo: Os escoamentos na superfície livre que se processam sobre forte declividade podem desenvolver instabilidades ao cabo de tempo finito. Tais instabilidades aparecem sob formas de ondas tipo "hydraulic jumps" bem espaçados e são denominadas Roll Waves. Estas ondas, longas e periódicas, podem ser contínuas ou descontínuas; contínuas em problema Shallow Water viscoso e descontínuas para o caso não viscoso. Tal fenômeno pode ser observado tanto em escoamentos naturais como em canais artificiais e vertedouros de barragens. Tratando-se de escoamento de Fluidos não newtonianos, tal fenômeno pode ser visto facilmente em lavas torrenciais, avalanchas ou "debris flows". Nesta dissertação foram analisados matematicamente e numericamente o comportamento e as condições de existência para a formação de Roll Waves em escoamentos laminares e turbulentos. Em escoamentos turbulentos toma-se como referência os trabalhos realizados por Maciel (2001) numa reologia Binghamiana. Para escoamentos laminares, cita-se o trabalho de Mei (1994) em uma reologia tipo Power Law. No plano numérico, para escoamentos turbulentos, foram utilizadas rotinas do MATLAB® versão 6.5 e, para escoamentos laminares, rotinas em FORTRAN 90; onde pôde-se analisar e comparar resultados para diversas reologias. O foco desta dissertação foi tratar o problema Roll Waves como uma instabilidade na vizinhança do regime uniforme para Fluidos não newtonianos, em regimes turbulentos e laminares. A reologia tratada e representativa de diversos escoamentos na natureza foi a de Herschel Bulkley. A partir desta dissertação deixa-se, como perspectiva futura, um estudo mais aprofundado sob formação de ondas em fluidos hiperconcentrados tipo Herschel Bulkley com abordagem experimental a fim de validar resultados apontados nesta pesquisa.
Abstract: Flows that happen over strong slope with free surface can develop instabilities after some finite time. Such wave shaped instabilities appear in the flow and are of the type "hydraulic jumps" well spaced and they are called Roll Waves. Those waves are long and periodic, continuous or discontinuous, continuous in viscous Shallow Water problems, and discontinuous for the inviscid case. Roll Waves are uncommon in natural flows, but they are common in man made channels and dams spillway. For flows of non Newtonian fluids such phenomenon can be seen easily in lava torrent, avalanche and debris flow. In this work it were mathematically and numerically analyzed the behavior and the existence conditions for the generation of Roll Waves within laminar and turbulent flows. For turbulent flows it is taken as reference the works done by Maciel (2001) dealing with a Bingham rheology. For laminar flows the reference is the work done by Mei (1994) using a Power Law rheology. Numerically, for turbulent flows it were used MATLAB® 6.5 procedures and for laminar flows FORTRAN 90 procedures were developed. Using these reference procedures it was obtained compared and analyzed results for several rheologies. This work left as future perspective a deeper study about the generation of waves in hipper concentrated fluids such as Herschel Bulkley fluid, with an experimental approach aiming to validate results produced. The focus of this work was to treat the so called Roll Waves problem as an instability in the vicinity of the uniform flow regime for non Newtonian fluids under laminar and turbulent flow regimes. The Herschel Bulkley rheology that was treated in this work is representative of several flows that happen in nature.
Mestre
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Nyekwe, Ichegbo Maxwell. "Investigation of factors effecting yield stress determinations using the slump test." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/2160.
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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2008.Certain non-Newtonian fluids exhibit a yield stress which can be measured with a variety of instruments varying from very sophisticated rotary and tube viscometers to hand-held slump cones and cylinders of various sizes. Accurate yield stress measurement is significant for process design and disposal operations for thickenend tailings. The slump value was first related to the yield stress by Murata (1984). Later, that work was corrected by Christensen (1991) for an error in the mathematical analysis. Slump, based on a circular cylindrical geometry was first investigated by Chandler (1986). These concepts led to the study by Pashias et al., (1996) that formed the basis for the current research. The Flow Process Research Centre (FPRC) at the Cape Peninsula University of Technology developed a slump meter designed to lift the cone or cylinder vertically at controlled lifting speeds. In addition the simple hand-held cylinder which is an adaptation of slump cones which were originally developed by the concrete industry to determine the flowability of fresh concrete was also used. The vane technique was used as a control. Cones and cylinders made of stainless steel and PVC were fitted to the slump meter. The yield stresses of four non-Newtonian fluids at different concentrations were tested in four different configurations at different lift speeds to ascertain whether the measuring position, lift speed, slip, geometry, wall surface material, and stability has an effect on the value of yield stress measured. The effect of different predictive models was also ascertained.The cylinder, lump and cone models relating slump to yield stress was used in the dimensional analysis of the results. The objective of this work was to determine if the slump tests (cone, cylinder and the hand-held cylinder) would generate yield stress values comparable to those found using the vane technique. It was establised that there was no significant effect of lift speed, stability, geometry and wall surface material on the value of yield stress. The effect of measuring position on the value of yield stress calculated gave a difference of 25%. Using dimensional analysis, the lump model (Hallbom, 2005) more accurately predicts the material yield stress when using the hand-held cylinder as well as all the cone results (due to its specific geometry), and cylinder configurations, thus affirming the work of Clayton et al., 2003. It is concluded that, although the materials and concentrations tested induced errors within 40%, the hand-held cylinder shows promise as a reliable, quick and simple way of measuring the yield stress.
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Domurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS478/document.
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Une étude numérique des suspensions diluées à base d'un fluide à matrice non newtonienne et de particules sphéroïdales rigides est réalisée. Un fluide de Carreau décrit la matrice non newtonienne. Le cas particulier des particules sphériques rigides est pris en compte. Ici, on simule un écoulement élongationnel uniaxial autour d'une sphère et on utilise l'homogénéisation numérique pour obtenir la viscosité apparente de la suspension diluée pour différents taux de déformation appliqués et différents exposants de dilution. Dans le régime newtonien, on obtient le fameux résultat d'Einstein pour la viscosité d'une suspension diluée de particules sphériques rigides. Dans le régime de la loi sur la puissance, on constate que la viscosité intrinsèque ne dépend que de l'exposant d'amincissement. En utilisant les résultats de la simulation, une modification du modèle de Carreau pour les suspensions diluées avec un fluide de matrice non newtonienne est proposée. Pour étudier l'influence de la forme des particules, une autre étude numérique est réalisée. En particulier, différents écoulements autour de particules sphéroïdales de différentes orientations sont simulés et une homogénéisation numérique est utilisée pour obtenir la viscosité intrinsèque de la suspension en fonction de la vitesse de déformation appliquée, de l'exposant d'amincissement et du rapport de forme. A partir des résultats, il est possible d'extraire les coefficients rhéologiques du modèle Lipscomb. Dans le régime newtonien, les résultats de simulation coïncident avec les prévisions de Lipscomb. Dans le régime de la loi de puissance, les coefficients rhéologiques dépendent fortement de l'exposant d'éclaircie. De plus, les résultats de la simulation indiquent que les coefficients rhéologiques dépendent en outre de l'orientation des particules en régime non linéaireA numerical study of dilute suspensions based on a non-Newtonian matrix fluid and rigid spheroidal particles is performed. A Carreau fluid describes the non-Newtonian matrix. The special case of rigid spherical particles is considered. Here, a uniaxial elongational flow around a sphere is simulated and numerical homogenization is used to obtain the bulk viscosity of the dilute suspension for different applied rates of deformation and different thinning exponents. In the Newtonian regime the well-known Einstein result for the viscosity of a dilute suspension of rigid spherical particles is obtained. In the power-law regime it is found that the intrinsic viscosity depends only on the thinning exponent. Utilizing the simulation results a modification of the Carreau model for dilute suspensions with a non-Newtonian matrix fluid is proposed. To investigate the influence of the particle shape another numerical study is performed. In particular, different flows around spheroidal particles with different orientations are simulated and numerical homogenization is used to obtain the intrinsic viscosity of the suspension as function of applied rate of deformation, thinning exponent and aspect ratio. From the results it is possible to extract the rheological coefficients of the Lipscomb model. In the Newtonian regime the simulation results coincide with Lipscomb’s predictions. In the power-law regime the rheological coefficients depend strongly on the thinning exponent. Furthermore, simulation results indicate that the rheological coefficients additionally depend on the particle orientation in the non-linear regime
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Kian, Jacqueline de Miranda. "Topology optimization method applied to design channels considering non-newtonian fluid flow." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-05012018-084558/.
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The study of non-Newtonian flow is presents itself as relevant in bioengineering field, specially for design of devices that conduct blood, as arterial bypass grafts. Improvements in reducing energy dissipation and blood cell damage caused by artificial flows can be achieved by using numerical simulation and optimization methods. Thus, the present work proposes the study of design channels for steady, incompressible non-Newtonian flow, by using Topology Optimization Method based on the density method. The fluid flow is modeled with the Navier-Stokes equations coupled with Carreau-Yasuda constitutive equation for the dynamic viscosity to take into account the effects of the non-Newtonian blood properties. The Topology Optimization Method distributes regions of solid and fluid, given a volume constraint, within a specified domain in order to obtain a geometry and layout that minimizes energy dissipation, shear stress and vorticity by using the material pseudo-density as design variable. To apply this method to fluidic systems design, a fictional porous media based on Darcy equation is introduced. The flow model is implemented in its discrete form by using the Finite Element Method through the OpenSource platform FEniCS, applied to automate the solution of mathematical models based on differential equations. The optimization problem is solved by using the library DOLFIN-adjoint and IPOpt optimizer. Optimized topologies of channels for blood flow, focusing in arterial bypass grafts, are presented to illustrate the proposed method.O estudo de escoamento de fluidos não-Newtonianos apresenta-se relevante no campo de bioengenharia, em especial no projeto de dispositivos para condução de sangue, como bypass arterial. Melhorias na redução de dissipação de energia e no dano às células sanguíneas causados por fluxos artificiais podem ser obtidas através do uso de técnicas de simulação e otimização numéricas. Deste modo, este trabalho propõe o estudo do projeto de canais para escoamentos incompressíveis em regime permanente de fluidos não-Newtonianos através do Método de Otimização Topológica baseado no método de densidade. O escoamento é modelado com as equações de Navier-Stokes acopladas com a equação constitutiva de Carreau-Yasuda para a viscosidade dinâmica, para que sejam considerados os efeitos das propriedades não-Newtonianas do sangue. O Método de Otimização Topológica distribui regiões de sólido e fluido, dada uma restrição de volume, dentro de um domínio especificado de modo a obter uma geometria e configuração que minimize a dissipação de energia, tensão de cisalhamento e vorticidade, utilizando a pseudo-densidade do material como variável de projeto. Para aplicar este método a sistemas fluidos, um meio poroso fictício, baseado na equação de Darcy, é introduzido. O modelo de escoamento é implementado em sua forma discreta utilizando o Método de Elementos Finitos através da plataforma OpenSource FEniCS, aplicada para automatizar a solução dos modelos matemáticos baseados em equações diferenciais, e o problema de otimização é resolvido utilizando a biblioteca DOLFIN-adjoint e otimizador IPOpt. Topologias otimizadas de canais para fluxo de sangue, com foco em bypass arterial, são apresentadas para ilustrar o método proposto.
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DEVARAKONDA, SURENDRA BALAJI. "BIOPARTICLE SEPARATION IN NON-NEWTONIAN FLUID USING PULSED FLOW IN MICRO-CHANNELS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155322288.
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Chetry, Manisha. "Advanced reduced-order modeling and parametric sampling for non-Newtonian fluid flows." Electronic Thesis or Diss., Ecole centrale de Nantes, 2023. http://www.theses.fr/2023ECDN0011.
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Le sujet de cette thèse porte sur laréduction d'ordre de modèle (MOR) deproblèmes d'écoulement non-Newtonianparamétrés qui ont des applicationsindustrielles importantes. Les méthodestraditionnelles de réduction de l'ordre desmodèles limitent les performances decalcul de ces problèmes hautement nonlinéaires, nous suggérons donc une techniqued'hyper-réduction avancée basée sur uneapproximation sparse de l'évaluation destermes non linéaire à complexité reduite.Nous proposons également une stratégie destabilisation hors ligne pour stabiliser le modèleconstitutif dans le modèle d'ordre réduit quiest moins cher à calculer tout en maintenant laprécision du modèle d'ordre complet. Lacombinaison des deux réduit drastiquement lecoût du processeur, augmentantinévitablement les performances du MOR. Cetravail est validé sur deux problèmes debenchmark. En outre, une stratégied'échantillonnage adaptatif est égalementprésentée dans ce manuscrit, qui est réaliséeen tirant parti de l'approximation des modèlesmulti-fidélité. Vers la fin de la thèse, nousabordons un autre problème qui estgénéralement observé dans les cas où desmaillages d'éléments finis adaptatifs sontdéployés. Dans de tels cas, les méthodes MORne parviennent pas à produire unereprésentation de faible dimension car lessnapshots ne sont pas des vecteurs de mêmelongueur. Par conséquent, nous suggérons uneméthodologie qui peut générer des fonctionsde base réduites pour des snapshotsadaptativeThe subject of this thesis concernsmodel-order reduction (MOR) of parameterizednon-Newtonian flow problems that havesignificant industrial applications. TraditionalMOR methods constrain the computationalperformance of such highly nonlinear problems,so we suggest a state-of-the-art hyper-reductiontechnique based on a sparse approximation totackle the evaluation of nonlinear terms at muchreduced complexity. We also provide offlinestabilization strategy for stabilizing theconstitutive model in the reduced order modelframework that is less expensive to computewhile maintaining the full order model's (FOM)accuracy. Combining the two significantlylowers the CPU cost as compared to the FOMevaluation which inevitably boosts MORperformance. This work is validated on twobenchmark flow problems. Additionally, anadaptive sampling strategy is also presented inthis manuscript which is achieved byleveraging multi-fidelity model approximation.Towards the end of the thesis, we addressanother issue that is typically observed forcases when adaptive finite element meshesare deployed. In such cases, MOR methods failto produce a low-dimensional representationsince the snapshots are not vectors of samelength. We therefore, suggest an alternatemethod that can generate reduced basisfunctions for database of space-adaptedsnapshots
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Kheng, Tan Ka. "Gas diffusion into viscous and non-Newtonian liquids and the onset of convection." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321528.
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