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1
Kalejaiye, Bolarinwa Olumuyiwa. „The flow of miscible and immiscible fluids in the Earth's subsurface“. Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619654.
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2
Eastwood, Craig D. „The break-up of immiscible fluids in turbulent flows /“. Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3044776.
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Fisher, Charles Edward. „The Effects of a Navier-Slip Boundary Condition on the Flow of Two Immiscible Fluids in a Microchannel“. Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/294.
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We consider the flow of two immiscible fluids in a thin inclined channel subject to gravity and a change in pressure. In particular, we focus on the effects of Navier slip along the channel walls on the long-wave linear stability. Of interest are two different physical scenarios. The first corresponds to two incompressible fluid layers separated by a sharp interface, while the second focuses on a more dense fluid below a compressible gas. From a lubrication analysis, we find in the first scenario that the system is stable in the zero-Reynolds number limit with the slip effects modifying the decay rate of the stable perturbation. In the case of the Rayeligh-Taylor problem, slip along the less dense fluid wall has a destabilizing effect. In the second scenario, fluid inertia is pertinent, and we find neutral stability criteria are not significantly affected with the presence of slip.
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Kiriakidis, Dionissios Georgios. „Computer simulations of two-fluid immiscible displacement flow in porous media“. Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7914.
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Two general-purpose computer programs have been developed for modelling the displacement of a wetting fluid by a non-wetting one in porous media. A microscopic approach is applied for the solution of the governing equations at the pore level. The porous medium is represented by a two-dimensional network of interconnected capillaries. One program makes use of a stochastic approach based on the aspects of random walks, invasion percolation and on the notion of the phase diagram for immiscible displacement. The other program makes use of a deterministic approach based on a relaxation technique in order to solve for the pressure field, and on certain rules for the advancement of the interface. The series of simulations undertaken successfully predicts certain important phenomena such as: (a) monophasic flow in porous media, (b) the effects of capillary and viscous forces on the dynamic behaviour of the displacing fluid and on the oil recovery, (c) the island formation and the island size distribution as a result of the interplay of viscous and capillary forces, (d) the fractal behaviour of the displacing fluid, (e) the transition from one distinct behaviour of the displacing fluid to another, and (f) the effects of local anisotropy and heterogeneity of the porous medium on the dynamic behaviour of the displacing fluid. The validity of the algorithms is tested by comparing the numerical results with physical experiments available in the literature. Comparisons between the two approaches reveal that (a) the stochastic approach is more efficient in terms of execution time in the computer, (b) the deterministic approach better describes the physics of the problem, and (c) the deterministic approach has more potential to be extended to other problems. It is proposed that the present programs can be used to successfully predict two-fluid immiscible displacement flow in porous media for other relevant situations.
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PIMENTEL, ISMAEL ANDRADE. „AN ADAPTIVE MESHFREE ADVECTION METHOD FOR TWO-PHASE FLOW PROBLEMS OF INCOMPRESSIBLE AND IMMISCIBLE FLUIDS THROUGH THREEDIMENSIONAL HETEROGENEOUS POROUS MEDIA“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33594@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Esta tese propõe um método meshfree adaptativo de advecção para problemas de fluxo bifásico de fluidos incompressíveis e imiscíveis em meios porosos heterogêneos tridimensionais. Este método se baseia principalmente na combinação do método Semi-Lagrangeano adaptativo com interpolação local meshfree usando splines poliharmônicas como funções de base radial. O método proposto é uma melhoria e uma extensão do método adaptativo meshfree AMMoC proposto por Iske e Kaser (2005) para modelagem 2D de reservatórios de petróleo. Inicialmente este trabalho propõe um modelo em duas dimensões, contribuindo com uma melhoria significativa no cálculo do Laplaciano, utilizando os métodos meshfree de Hermite e Kansa. Depois, o método é ampliado para três dimensões (3D) e para um meio poroso heterogêneo. O método proposto é testado com o problema de five spot e os resultados são comparados com os obtidos por sistemas bem conhecidos na indústria de petróleo.
This thesis proposes an adaptive meshfree advection method for two-phase flow problems of incompressible and immiscible fluids through three-dimensional heterogeneous porous media. This method is based mainly on a combination of adaptive semi-Lagrangian method with local meshfree interpolation using polyharmonic splines as radial basis functions. The proposed method is an improvement and extension of the adaptive meshfree advection scheme AMMoC proposed by Iske and Kaser (2005) for 2D oil reservoir modeling. Initially this work proposes a model in two dimensions, contributing to a significant improvement in the calculation of the Laplacian, using the meshfree methods of Hermite and Kansa. Then, the method is extended to three dimensions (3D) and a heterogeneous porous medium. The proposed method is tested with the five spot problem and the results are compared with those obtained by well-known systems in the oil industry.
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Mayur, Manik. „Study of interface evolution between two immiscible fluids due to a time periodic electric field in a microfluidic channel“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00983473.
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Since the past decade, use of electro-osmotic flow (EOF) as an alternative flow mechanism in microdevices is becoming more popular due to its less bulky and low maintenance system design. However, one of the biggest shortcomings for its usage in mainstream applications is that it requires the concerned liquid to be electrically conductive. One idea can be to use the flow of conductive fluids to transport non-conductive liquids passively via interfacial shear transfer. Such an idea can has numerous applications in a wide range of fields like bio-chemical processing (e.g. lab-on-a-chip reactors, mixers, etc.), to oil extraction from porous rock formations. One of the significant characteristics of micro-scale flows is high surface to volume ratio, which significantly highlights the role of multi-phase interfaces in such dynamics. The presence of a fluid-fluid interface in an EOF necessitates the characterization of the parameters responsible for hydrodynamic instability of such systems. The present work focuses on the role of steady and time-dependent electric stress (Maxwell stress), capillary force and disjoining pressure on fluid-fluid interfacial instability. A linear stability analysis of interfacial perturbation was performed for a thin film of electrolyte under DC and AC electric fields. Through long wave asymptotic analysis of the Orr-Sommerfeld equations, parametric stability thresholds of a thin aqueous film explored. Further, a set of experiments were performed in order to characterize the EOF in a rectangular microchannel. With the help of a Particle Tracking Velocimetry analysis, velocity distributions were obtained which agreed well to the theoretical values. This was further used to estimate PDMS zeta potential, which was found to be within the reported values in the existing literature. Liquid-liquid interfacial deformation was also explored under a time-periodic EOF and a wide range of the magnitudes of capillary force, and diffusive and convective transport.
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Lunda, Filip. „Studium proudění na rozhraní nemísitelných kapalin“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444285.
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This theses deals with flow of two immisible fluid in horizontal pipeline. First part teoretically describes immisible flow. What follows is experimental measurement in wich experimental track was adjusted for inlet of oil from the top. Water and corn germ oil were used as fluids. There were observed many modes of flow on the track. After that PIV was described and measured. PIV was done for measurement of values of velocity vectors. Simulation of one chosen mode was developed in the last chapter. This simulation was done in Ansys Fluent with help of VOF method. Simulation was done both in 3D and 2D pipeline. In the end these simulation were compared with experiment measurement and were critically evaluated.
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Yang, Zhibing. „Multiphase Contamination in Rock Fractures : Fluid Displacement and Interphase Mass Transfer“. Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183720.
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Multiphase flow and transport in fractured rock is of importance to many practical and engineering applications. In the field of groundwater hydrology an issue of significant environmental concern is the release of dense non-aqueous phase liquids (DNAPLs) which can cause long-term groundwater contamination in fractured aquifers. This study deals with two fundamental processes – fluid displacement and interphase mass transfer – concerning the behavior of the multiphase contaminants in fractured media. The focus of this work has been placed on improving the current understanding of small-scale (single fracture) physics by a combined effort of numerical modeling analysis, laboratory experiments and model development. This thesis contributes to the improved understanding through several aspects. Firstly, the effect of aperture variability, as characterized by geostatistical parameters such as standard deviation and correlation length, on the DNAPL entrapment, dissolution and source-depletion behaviors in single fractures was revealed. Secondly, a novel, generalized approach (adaptive circle fitting approach) to account for the effect of in-plane curvature of fluid-fluid interfaces on immiscible fluid displacement was developed; the new approach has demonstrated good performance when applied to simulate previously published experimental data. Thirdly, the performance of a continuum-based two-phase flow model and an invasion percolation model was compared for modeling fluid displacement in a variable-aperture fracture and the dependence of fracture-scale capillary pressure – saturation relationships on aperture variability was studied. Lastly, through experimental studies and mechanistic numerical modeling of DNAPL dissolution, kinetic mass transfer characteristics of two different entrapment configurations (residual blobs and dead-end pools) were investigated. The obtained understanding from this thesis will be useful for predictive modeling of multiphase contaminant behavior at a larger (fracture network) scale.Flerfasflöde och ämnestransport i sprickigt berg är av betydelse för många praktiska och tekniska problem. Tunga, svårlösliga organiska vätskor (engelska: dense non-aqueous phase liquids: DNAPLs; t.ex. klorerade lösningsmedel) kan orsaka långvarig förorening av vattenresurser, inklusive akviferer i sprickigt berg, och utgör ett viktigt miljöproblem inom grundvattenhydrologin. Denna studie behandlar två fundamentala processer för spridning av flerfasföroreningar i sprickiga medier – utbredning av den organiska vätskan och massöverföring mellan organisk vätska och vatten. Arbetet har fokuserat på att förbättra nuvarande kunskap om de fysikaliska processerna på liten skala (enskilda sprickor) genom en kombination av numerisk modellering, laboratorieexperiment och modellutveckling. Avhandlingen har bidragit till utökad processförståelse i flera avseenden. För det första har arbetet belyst effekterna av sprickaperturens variabilitet, uttryckt med geostatistiska parametrar som standardavvikelse och rumslig korrelationslängd, på fastläggning och lösning av organiska vätskor i enskilda sprickor, samt utmattningsbeteendet hos dessa källor till grundvattenförorening. För det andra har en ny, generell metod (adaptiva cirkelpassningsmetoden) för att ta hänsyn till effekten av krökningen av gränsytan mellan organisk vätska och vatten i sprickplanet utvecklats; denna metod har visats fungera väl i simuleringar av tidigare publicerade experimentella data. För det tredje, har en jämförelse gjorts mellan en kontinuumbaserad tvåfasflödesmodell och en invasions-perkolationsmodell med avseende på hur väl de kan simulera tvåfasflöde i en spricka med varierande apertur. Här studerades även hur relationen mellan kapillärtryck och mättnadsgrad på sprickplansskala beror av variabiliteten i sprickapertur. Till sist undersöktes lösning av den organiska vätskan i grundvatten för två fastläggningsscenarier (fastläggning i immobila droppar och ansamling i fällor – ”återvändssprickor”) både genom experiment och mekanistisk numerisk modellering. Kunskapen som tagits fram i denna avhandling bedöms vara användbar även för att modellera spridningen av flerfasföroreningar på större (spricknätverks-) skalor.
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Xi, Shi Tong. „Transient turbulent jets of miscible and immiscible fluids“. Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38198.
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Schechter, David S. „Immiscible flow behaviour in porous media“. Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234777.
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Sheng, Jopan. „Multiphase immiscible flow through porous media“. Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/53630.
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A finite element model is developed for multiphase flow through soil involving three immiscible fluids: namely air, water, and an organic fluid. A variational method is employed for the finite element formulation corresponding to the coupled differential equations governing the flow of the three fluid phase porous medium system with constant air phase pressure. Constitutive relationships for fluid conductivities and saturations as functions of fluid pressures which may be calibrated from two-phase laboratory measurements, are employed in the finite element program. The solution procedure uses iteration by a modified Picard method to handle the nonlinear properties and the backward method for a stable time integration. Laboratory experiments involving soil columns initially saturated with water and displaced by p-cymene (benzene-derivative hydrocarbon) under constant pressure were simulated by the finite element model to validate the numerical model and formulation for constitutive properties. Transient water outflow predicted using independently measured capillary head-saturation data agreed well with observed outflow data. Two-dimensional simulations are presented for eleven hypothetical field cases involving introduction of an organic fluid near the soil surface due to leakage from an underground storage tank. The subsequent transport of the organic fluid in the variably saturated vadose and ground water zones is analysed.Ph. D.
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Pan, Xuefeng. „Immiscible two-phase flow in a fracture“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0025/NQ47907.pdf.
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Caruana, Albert. „Immiscible flow behaviour within heterogeneous porous media“. Thesis, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285232.
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Wang, Jin. „A numerical approach for the interfacial motion between two immiscible incompressible fluids“. Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092675815.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiii, 152 p.; also includes graphics. Includes bibliographical references (p. 147-152).
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Rannou, Guillaume. „Lattice-Boltzmann method and immiscible two-phase flow“. Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26560.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Cyrus K. Aidun; Committee Member: Marc K. Smith; Committee Member: S. Mostafa Ghiaasiaan. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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McCarvill, John. „The dynamics of a moving boundary between immiscible fluids in a porous medium /“. Online version of thesis, 1991. http://hdl.handle.net/1850/11003.
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Jofre, Cruanyes Lluís. „Numerical simulation of multiphase immiscible flow on unstructured meshes“. Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/277545.
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The present thesis aims at developing a basis for the numerical simulation of multiphase flows of immiscible fluids. This approach, although limited by the computational power of the present computers, is potentially very important, since most of the physical phenomena of these flows often happen on space and time scales where experimental techniques are impossible to be utilized in practice. In particular, this research is focused on developing numerical discretizations suitable for three-dimensional (3-D) unstructured meshes.
In detail, the first chapter delimits the considered multiphase flows to the case in which the components are immiscible fluids. In particular, the focus is placed on those cases where two or more continuous streams of different fluids are separated by interfaces, and hence, correspondingly named separated flows. Additionally, once the type of flow is determined, the chapter introduces the physical characteristics and the models available to predict its behavior, as well as the mathematical formulation that sustains the numerical techniques developed within this thesis.
The second chapter introduces and analyzes a new geometrical Volume-of-Fluid (VOF) method for capturing interfaces on 3-D Cartesian and unstructured meshes. The method reconstructs interfaces as first- and second-order piecewise planar approximations (PLIC), and advects volumes in a single unsplit Lagrangian-Eulerian (LE) geometrical algorithm based on constructing flux polyhedrons by tracing back the Lagrangian trajectories of the cell-vertex velocities. In this way, the situations of overlapping between flux polyhedrons are minimized.
Complementing the previous chapter, the third one proposes a parallelization strategy for the VOF method. The main obstacle is that the computing costs are concentrated in the interface between fluids. Consequently, if the interface is not homogeneously distributed, standard domain decomposition (DD) strategies lead to imbalanced workload distributions. Hence, the new strategy is based on a load balancing process complementary to the underlying domain decomposition. Its parallel efficiency has been analyzed using up to 1024 CPU-cores, and the results obtained show a gain with respect to the standard DD strategy up to 12x, depending on the size of the interface and the initial distribution.
The fourth chapter describes the discretization of the single-phase Navier-Stokes equations to later extend it to the case of multiphase immiscible flow. One of the most important characteristics of the discretization schemes, aside from accuracy, is their capacity to discretely conserve kinetic energy, specially when solving turbulent flow. Hence, this chapter analyzes the accuracy and conservation properties of two particular collocated and staggered mesh schemes.
The extension of the numerical schemes suitable for the single-phase Navier-Stokes equations to the case of multiphase immiscible flow is developed in the fifth chapter. Particularly, while the numerical techniques for the simulation of turbulent flow have evolved to discretely preserve mass, momentum and, specially, kinetic energy, the mesh schemes for the discretization of multiphase immiscible flow have evolved to improve their stability and robustness. Therefore, this chapter presents and analyzes two particular collocated and staggered mesh discretizations, able to simulate multiphase immiscible flow, which favor the discrete conservation of mass, momentum and kinetic energy.
Finally, the sixth chapter numerically simulates the Richtmyer-Meshkov (RM) instability of two incompressible immiscible liquids.
This chapter is a general assessment of the numerical methods developed along this thesis. In particular, the instability has been simulated by means of a VOF method and a staggered mesh scheme. The corresponding numerical results have shown the capacity of the discrete system to obtain accurate results for the RM instability.Aquesta tesi té com a objectiu desenvolupar una base per a la simulació numèrica de fluids multi-fase immiscibles. Aquesta estratègia, encara que limitada per la potència computacional dels computadors actuals, és potencialment molt important, ja que la majoria de la fenomenologia d'aquests fluids sovint passa en escales temporals i especials on les tècniques experimentals no poden ser utilitzades. En particular, aquest treball es centra en desenvolupar discretitzacions numèriques aptes per a malles no-estructurades en tres dimensions (3-D). En detall, el primer capítol delimita els casos multifásics considerats al cas en que els components són fluids immiscibles. En particular, la tesi es centra en aquells casos en que dos o més fluids diferents són separats per interfases, i per tant, corresponentment anomenats fluxos separats. A més a més, un cop el tipus de flux es determinat, el capítol introdueix les característiques físiques i els models disponibles per predir el seu comportament, així com també la formulació matemàtica i les tècniques numèriques desenvolupades en aquesta tesi. El segon capítol introdueix i analitza un nou mètode "Volume-of-Fluid" (VOF) apte per a capturar interfases en malles Cartesianes i no-estructurades 3-D. El mètode reconstrueix les interfases com aproximacions "piecewise planar approximations" (PLIC) de primer i segon ordre, i advecciona els volums amb un algoritme geomètric "unsplit Lagrangian-Eulerian" (LE) basat en construïr els poliedres a partir de les velocitats dels vèrtexs de les celdes. D'aquesta manera, les situacions de sobre-solapament entre poliedres són minimitzades. Complementant el capítol anterior, el tercer proposa una estratègia de paral·lelització pel mètode VOF. L'obstacle principal és que els costos computacionals estan concentrats en les celdes de l'interfase entre fluids. En conseqüència, si la interfase no està ben distribuïda, les estratègies de "domain decomposition" (DD) resulten en distribucions de càrrega desequilibrades. Per tant, la nova estratègia està basada en un procés de balanceig de càrrega complementària a la DD. La seva eficiència en paral·lel ha sigut analitzada utilitzant fins a 1024 CPU-cores, i els resultats obtinguts mostren uns guanys respecte l'estratègia DD de fins a 12x, depenent del tamany de la interfase i de la distribució inicial. El quart capítol descriu la discretització de les equacions de Navier-Stokes per a una sola fase, per després estendre-ho al cas multi-fase. Una de les característiques més importants dels esquemes de discretització, a part de la precisió, és la seva capacitat per conservar discretament l'energia cinètica, específicament en el cas de fluxos turbulents. Per tant, aquest capítol analitza la precisió i propietats de conservació de dos esquemes de malla diferents: "collocated" i "staggered". L'extensió dels esquemes de malla aptes per els casos de una sola fase als casos multi-fase es desenvolupa en el cinquè capítol. En particular, així com en el cas de la simulació de la turbulència les tècniques numèriques han evolucionat per a preservar discretament massa, moment i energia cinètica, els esquemes de malla per a la discretització de fluxos multi-fase han evolucionat per millorar la seva estabilitat i robustesa. Per lo tant, aquest capítol presenta i analitza dos discretitzacions de malla "collocated" i "staggered" particulars, aptes per simular fluxos multi-fase, que afavoreixen la conservació discreta de massa, moment i energia cinètica. Finalment, el capítol sis simula numèricament la inestabilitat de Richtmyer-Meshkov (RM) de dos fluids immiscibles i incompressibles. Aquest capítol es una prova general dels mètodes numèrics desenvolupats al llarg de la tesi. En particular, la inestabilitat ha sigut simulada mitjançant un mètode VOF i un esquema de malla "staggered". Els resultats numèrics corresponents han demostrat la capacitat del sistema discret en obtenir bons resultats per la inestabilitat RM.
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Bristow, Robert Philip. „Micromodels of immiscible two-phase flow in porous media“. Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235763.
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The research is a study on the microscopic scale of the immiscible displacement of oil by water in a porous medium such as sandstone. Of particular interest (with application to the oil industry) are the residual saturation of oil, the permeability to water at residual oil saturation and the maximum trapped blob size. Initially the effects of gravity, surface tension and distribution of pore sizes were studied in a computer simulation of a buoyancy driven, quasi-static invasion. The rock was modelled as a three-dimensional lattice of spherical pores connected by narrow cylindrical throats. With the rock water-wet, the tendency of the surface tension to favour the invasion of smaller pores led to a larger residual oil saturation by pore volume than by pore numbers. Also bourne out were some scaling arguments based on percolation theory for the maximum trapped blob size as a function of the relative strength of buoyancy and surface tension forces. The second part of the research investigated the interaction of viscous and surface tension forces. As this is a much more complicated problem, involving the solution of flow equations, the invasion process was first simulated with exact equations of motion on small networks (up to 10x10), where surface tension effects dominate. From these simulations a simplified set of rules was developed to determine which pore in a locality on the oil-water interface is invaded and how long the invasion takes. These rules include a viscous correction to the dominant surface tension forces. Finally, some theory has been developed for the inclusion of the small-scale analysis into a larger model, allowing a full simulation of the viscous dominated invasion to be performed.
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Thompson, Matthew S. „Extensional Flow Blending of Immiscible Polymers with Nanoparticle Stabilization“. Thesis, West Virginia University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10247747.
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Polymer blending facilitates the combination of the attractive attributes of two or more polymers while compensating for the unfavorable ones. Most polymers are thermodynamically incompatible with one another, and their blending yields a two-phase microstructure. This morphology generally determines the mechanical and rheological properties of the blend system which then determine its applications. Morphology development typically involves deformation of the dispersed phase followed by drop breakup. However, drop coalescence competes with this process, and ultimately a balance must be reached between these two competing processes. Extensional flow fields are known to promote drop breakup and are especially important for blends with high viscosity ratios, that is for blends where the viscosity of the dispersed phase is at least about 3.8 times greater than that of the matrix phase. Coalescence may be attenuated by compatibilizers that modify the interface between the polymer phases. Nanoparticles with tuned surface chemistry may also be used as compatibilizers. A combination of extensional flow and nanoparticle stabilization should, therefore, result in a fine, stable morphology.
To begin the investigation toward the effects of extensional flow blending with and without the incorporation of nanoparticles, preliminary results were obtained using two different polymer blend systems: polycarbonate (PC)/styrene acrylonitrile (SAN) and polystyrene (PS)/linear low-density polyethylene (LLDPE). However, the majority of the presented results involve blends of high-density polyethylene (HDPE) dispersed in PS. With this blend system, with the material grades selected, the viscosity ratio exceeded 3.8 over the entire domain of deformation rates anticipated in the processing used. Coarse blends of various compositions were formulated using shear flow in an internal mixer or in a twin-screw extruder. These blends were subjected to extensional flow in converging dies of different geometries and where more than one stretching episode was possible; the temperature, total strain, and flow rate were varied, among other factors, in a systematic manner. Experiments were repeated in the presence of various grades of fumed nanosilica of different sizes and surface treatments, which imparted different surface tension and relative surface polarity (hydrophilic versus hydrophobic) for the nanoparticles. The mixing sequence was varied including premixing the nanosilica into the thermodynamically non-preferred polymer phase.
Scanning electron microscopy (SEM) was used to determine the size and size distribution of the dispersed polymer phase. The material was typically sectioned in the flow direction, but sectioning in the direction perpendicular to flow and etching, or selectively dissolving, one phase or the other was also investigated. The primary effect of extensional flow blending was to reduce the volume-average diameter of the dispersed polymer phase, especially with increasing strains and flow rates, or strain rates, which is directly dependent on both. Finding suitable conditions for the nanoparticles to selectively localize at the HDPE/PS interface was challenging, but relatively small amounts of nanoparticles dispersed in the PS matrix decreased the volume-average diameter of HDPE drops. When the nanosilica was preloaded into the HDPE dispersed phase, very coarse initial blends were produced which then exhibited dramatic decreases in phase size with extensional flow. These and other results are properly organized and presented.
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Kéchavarzi, Cédric. „Physical modelling of immiscible multiphase flow in porous media“. Thesis, University of Cambridge, 2001. https://www.repository.cam.ac.uk/handle/1810/251766.
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Stokes, Jason R. „Swirling flow of viscoelastic fluids /“. Connect to thesis, 1998. http://eprints.unimelb.edu.au/archive/00000686.
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Cordy, S. E. „Extensional flow of complex fluids“. Thesis, Swansea University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636294.
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The work reported in this Thesis involves studies of the extensional deformation of complex fluids. Complex fluids are so-called in terms of their composition, microstructure and rheology. Of particular interest in the work reported herein is the extensional viscosity of mobile (low shear viscosity) fluids in uniaxial extensional (or elongational flows) as this form of fluid determination is of wide concern within the process industries and is an important part of efforts in rheometry (the science of rheological measurement) to develop appropriate techniques for the measurement of extensional flow properties (in terms of a parameterisation of the resistance to extension). The principal experimental technique reported herein is a form of filament-stretching rheometer which generates a steady uniaxial extension of a fluid at the mid-point of a filament which is generated by the simultaneous motion of two confirming plate geometries. Difficulties which arise in this experiment and new approaches to their solution are described herein and the Thesis contains a comprehensive account of the design, construction, testing and refinement of such an instrument. Due to the relatively low rates of extension associated with filament-stretching rheometers, a new form of filament generation is described which involves fluid cavitation. Using this technique, which involves the generation of a rapidly stretching filament by the collapse of a gas-filled bubble, industrially relevant deformation rates are achieved and the technique has been successfully employed, for the first time, to provide a measure of resistance to extension of multigrade motor lubricants under process relevant conditions of fluid extension.
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Agg, D. A. „The flow of polymeric fluids“. Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233667.
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The thesis is concerned with the flow of polymeric fluids and their response to deformations. The current state of research into the rheology of polymers is reviewed and an introduction to non-Newtonian fluid mechanics is given. A novel numerical algorithm for simulating the flow of non-Newtonian fluids is presented, in which the fluid is represented by a set of Lagrangian particles embedded in it. Each particle carries a velocity and a stress with it as it moves through the flow geometry. The velocity gradient tensor and the divergence of the stress tensor are calculated for each particle by averaging over the neighbouring particles. The velocity is changed according to a discretised form of the equation of conservation of momentum and the stress is updated according to the constitutive equation for the fluid. Extra algorithms are presented to deal with the boundary conditions. The simulation is used to study the two-dimensional flow of a co-rotational Maxwell fluid past an array of cylinders between two walls. In the second part of the thesis, a computer simulation is developed which will allow the constitutive equation for a polymer melt to be replaced by a numerical version. Previous computer simulations of polymers are reviewed and a new, real space, reptation model is presented. This model is shown to have the correct behaviour for a reptating chain and is used to study the stress response to a step shear deformation. The long-term behaviour agrees with reptation theory, but the short-time behaviour is also found.
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Nourdeen, Hasan. „Upscaling immiscible capillary-controlled two-phase flow in porous media“. Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/61482.
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This thesis focuses primary on two-phase displacements under capillary-controlled flow conditions at relatively large scales, considering solution techniques that capture the dynamics of two-phase displacements for homogeneous flow domains, and deriving representative averages for heterogeneous systems with strong spacial variations in two-phase properties. First, we review main flow mechanisms encountered at large scales when capillary forces dominate the displacement process, where we present main solution techniques for homogeneous flow domains and introduce analytical treatments for other flow mechanisms that do not follow standard time-scaling. We also present a comprehensive investigation of spontaneous imbibition processes in porous rocks both numerically and analytically, and propose a simplified but accurate analytic approximation using perturbation theory, that considerably improves the implementation process, as compared with the original analytical solution. After that, an investigation of the impact of capillary backpressure on counter-current flow is performed, as this is considered one of the main drawbacks in using the continuum modelling approach. We then apply steady-state capillary-controlled upscaling in heterogeneous environment, where large-scale invasion percolation is coupled with a conventional Darcy solver to identify large-scale trapping due to capillary forces. In other words, a phase may fail to form a connected path across a given domain at capillary equilibrium, and some regions therefore may produce disconnected clusters. In such cases, conventional upscaling processes might not be accurate since identification and removal of these isolated clusters are extremely important to the global connectivity of the system and the stability of the numerical solvers. We present a comprehensive investigation using random absolute permeability fields, for water-wet, oil-wet and mixed-wet systems, where we show that in oil-wet and mixed-wet media, large-scale trapping of oil controlled by variations in local capillary pressure, may be more significant than the local trapping controlled by pore-scale displacement.
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Schmid, Karen Sophie. „Mathematical analysis, scaling and simulation of flow and transport during immiscible two-phase flow“. Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2547.
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Fluid flow and transport in fractured geological formations is of fundamental socio-economic importance, with applications ranging from oil recovery from the largest remaining hydrocarbon reserves to bioremediation techniques. Two mechanisms are particularly relevant for flow and transport, namely spontaneous imbibition (SI) and hydrodynamic dispersion. This thesis investigates the influence of SI and dispersion on flow and transport during immiscible two-phase flow. We make four main contributions. Firstly, we derive general, exact analytic solutions for SI that are valid for arbitrary petrophysical properties. This should finalize the decades-long search for analytical solutions for SI. Secondly, we derive the first non-dimensional time for SI that incorporates the influence of all parameters present in the two-phase Darcy formulation - a problem that was open for more than 90 years. Thirdly, we show how the growth of the dispersive zone depends on the flow regime and on adsorption. To that end we derive the first known set of analytical solutions for transport that fully accounts for the effects of capillarity, viscous forces and dispersion. Finally, we provide numerical tools to investigate the influence of heterogeneity by extending the higher order finite-element finite-volume method on unstructured grids to the case of transport and two-phase flow.
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Ducharme, Réjean 1970. „Capillary flow of non-Newtonian fluids“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23392.
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The flow of a two-dimensional incompressible non-Newtonian fluid, showing a viscoelastic behavior, has been studied using the White-Metzner model with a phenomenological law for the viscosity, the Spriggs' truncated power-law model. Our goal was to determine if these models could generate the oscillating instabilities appearing in such fluids at very high driving force. We studied the effect of various quantities on the time-dependent numerical simulations and noticed that the mesh length was not very important for the accuracy of the results. However, the time constant modulus appearing in the White-Metzner model and the applied pressure were of paramount importance for the relaxation time of a disruptive flow.We thus showed that this model was effective only at low pressure and that without adding new aspects to the study of the flow, such as compressibility, we could not obtain any oscillating flow at high pressure. Despite this fact, exact steady-state solutions, as well as a time-dependant solution in the case of very small Reynolds number ($R to$ 0), have been given.
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Al-Sharify, Zainab Talib Abidzaid. „Flow and mixing of complex fluids“. Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7673/.
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The mixing of complex fluids in stirred reactors is widly used in many industries. Mechanically agitated vessels are widely used in these industries such as wastewater treatment, pharmaceuticals, nuclear and food processing. Complex fluids are frequently encountered in these industries. There is growing interest in developing and studying these fluids, especially for those of shear thickening (ST) behaviour, due to the importance of their industrial applications such as flexible body armor and force damping applications which can protect a person from danger or risk and ultimately saveone’s life. Little work has been done to understand how to mix complex fluids effectively, mainly because of their opaque nature. In this thesis, new ST fluids formulations were developed and these fluids were used as a model fluid for mixing studies. The flow field in an opaque ST fluid was determined experimentally using the positron emission particle tracking (PEPT). In addition, the performance of axial, radial and mixed flow impellers in mixing complex fluids have been also studied using different experimental techniques and the computational fluid dynamics (CFD) simulations. Moreover, for the first time, PEPT has been used to investigate the flow field of floating particles in a stirred vessel. PEPT was used to investigate the two-phase flow field inside a stirred vessel of polypropylene particles in different types of rheological fluids, at the just drawdown speed for a wide range of solid concentrations from 1.8 vol% up to 46 vol%. The outcomes of this thesis are beneficial to many chemical processes, such as e.g. formulation processes in the pharmaceutical industry, whereby an essential step in the product development involving powder mixing is the ability to drawdown the floating solids. In addition, the outcome of this thesis can also be beneficial in identifying the ideal configuration of stirred vessels used in chemical processes where mixing is the central feature, for example, in the food and rubber industries. Moreover, the newly developed complex fluids (shear thickening fluids) can be used in many industrial and commercial applications such as in the defence industry (as liquid body armor) and also as part of the protective devices designed to minimise head and neck injuries that occur in some sports accidents such as in car racing, football, ice hockey etc.
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Wilson, Helen Jane. „Shear flow instabilities in viscoelastic fluids“. Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625082.
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The dissertation is concerned with the stability of channel flows of viscoelastic fluids. The content is primarily theoretical. The dissertation begins with a review of instabilities observed in experiments and then attempts to elucidate possible mechanisms using linear stability theory. The first section considers a previously known interfacial instability in coextrusion flows, whose mechanism is purely elastic. This instability is investigated in different parameter régimes for an Oldroyd-B fluid. The next section generalises the study to a continuously stratified fluid, and finds that a class of models with rapid variation in their elastic properties will also show the instability. These results are confirmed both numerically and using asymptotic methods. The fundamental mechanism of this "coextrusion" instability is the same as for the interfacial instability above. The next part concerns a shear-thinning White-Metzner fluid (i.e. a viscoelastic fluid having a relaxation time that is an instantaneous function of the local shear-rate). Evidence for another instability is found where the degree of thinning in the shear viscosity is high. The mechanism for this instability is fundamentally different from that in coextrusion. In the final section of the dissertation a study of two fluids of different constitutive types but identical base-state velocity and stress profiles shows that the criterion for the "coextrusion" instability depends on properties of the model itself. The flows in question are relevant to the practical problem of extrusion of polymeric liquids. The two instabilities found may provide mechanisms for experimental observations of helical distortions of extrudates. The demonstration that the constitutive type of a model has a crucial effect on its stability may have implications for future constitutive modelling in this field.
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Miller, Joel C. „Shear flow instabilities in viscoelastic fluids“. Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/245318.
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This dissertation is concerned with the theoretical study of the stability of viscoelastic shear flows. It is divided into two parts: part I studies inertialess coextrusion flows at large Weissenberg number where the instabilities are due to discontinuities in the elastic properties, and part II studies the effect of elasticity on the well-known inertial instabilities of inviscid flows with inflection points. We begin part I with a previously known short-wave instability of Upper Convected Maxwell and Oldroyd–B fluids at zero Reynolds number in Couette flow. We show that if the Weissenberg number is large, the instability persists with the same growth rate when the wavelength is longer than the channel width. Intriguingly, surface tension does not modify the growth rate. Previous explanations of elastic interfacial instabilities based on the jump in normal stress at the interface cannot apply to this instability. These results are confirmed both numerically and with asymptotic methods. We then consider Poiseuille flow and show that a new class of instability exists if the interface is close to the center-line. We analyse the scalings and show that it results from a change in the boundary layer structure of the Couette instability. The growth rates can be large, and the wavespeed can be faster than the base flow advection. We are unable to simplify the equations significantly, and asymptotic results are not available, so we use numerics to verify the results. In studying these instabilities we encounter some others which we mention, but do not analyse in detail. In part II we study the effect of elasticity on the inertial instability of flows with inflection points. We show that the elasticity modifies the development of cat’s eyes. The presence of extensional flow complicates the analysis. Consequently we use the FENE–CR equations.
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Karimfazli, Ida. „Buoyancy-driven flow of viscoplastic fluids“. Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54981.
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We study natural convection of viscoplastic fluids in 2D domains. A sufficiently large yield stress introduces a static solution to the Navier–Stokes equations that may not otherwise exist. We find conditions that guarantee such motionless regimes and investigate flow development between static and advective states. Considering three problems, we explore the various ways in which the yield stress modifies the hydrodynamics of steady and transient natural convection. We start by analyzing natural convection in an infinitely long rectangular cavity. Flow is driven by a constant horizontal temperature difference and a stabilizing stratification imposed on the walls. We classify different 1D flow regimes and establish that an arbitrary number of unyielded regions can exist in the domain. Secondly, considering a square cavity, we investigate conditional and unconditional stability of the stationary state. We study the transition of the fluid between conductive and advective states, revealing the possibility of temporary arrest of the flow at yield stresses less than the critical value. Finally, we study natural convection of viscoplastic fluids due to a heater of finite width positioned on the bottom wall of a cavity. We show that if the yield stress is less than the critical value, the flow starts after a finite time. We characterize transient flow and explain the processes that result in the observation of pulsing plumes at high Rayleigh. Overall, we investigate the force balance that governs the existence of steady motion, or lack thereof. When the steady regime is advective, we illustrate that depending on the boundary and initial conditions flow may start immediately or flow onset may be delayed by a finite time. We focus on problems where flow onset is due to dominance of buoyancy stresses and is not a consequence of hydrodynamic instability. In §4 we clarify the difference. Further, we explore transient flow dynamics and establish that the yield stress can intensify oscillatory transient features. This results in the dominance of different transport methods and corresponding timescales at different stages of flow development. We show that under appropriate conditions, this may lead to temporary flow arrest and create other noteworthy dynamics.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Elgibaly, Ahmed Ahmed Mohamed. „The simultaneous flow of two immiscible liquids through a porous medium“. Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239994.
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Chi, Bo Kyung Leal L. Gary. „The motion of immiscible drops and the stability of annular flow /“. Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-10102005-095730.
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Kristensen, Aleksander. „Flow properties of water-based drilling fluids“. Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23107.
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The objective of this master thesis was to investigate the flow properties of water based drilling fluids, utilizing measurements in both the micro and macro scale. The research was performed on two realistic drilling fluids by the use of a viscometer, a rheometer and a realistic flow loop, where the latter represents the macro scale. The research outcome could possibly improve the understanding of flow behavior in wellbores, and remove uncertainties associated with annular friction. The two fluids utilized in the research was made up with the goal of having equal rheological qualities, when measured with a Fann 35 viscometer. A more thorough examination of the two fluid's rheology was then executed by using a Anton Paar MCR302 rheometer. The macroscopic properties was researched employing a flow loop, capable of simulating realistic wellbore conditions.The main outcome of this thesis is that even though two fluids appear to have the same rheoligical properties when measured on simple equipment, their fundamental different microscopic structure will exhibit variations when the fluids are utilized in real applications.Due to problems encountered when mixing the fluids, as well as problems with one of the fluids itself, not all intended experiments were conducted. The experiments should be replicated with an emphasis on temperature control, avoiding bubbles and foam, and be conducted within a shorter time period.
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Jupp, Laurence. „Dynamic modeling of complex fluids under flow“. Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288304.
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Ahilan, R. V. „Flow of cohesionless grains in oscillatory fluids“. Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304431.
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Tshehla, Maashutha Samuel. „Two dimensional flow of variable viscosity fluids“. Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/4936.
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Boukany, Pouyan E. „Nonlinear Flow Behavior of Entangled DNA Fluids“. University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226681246.
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González, Segredo Nélido Jesús. „Lattice-Boltzmann and lattice-gas simulations of binary immiscible and ternary amphiphilic fluids in two and three dimensions“. Doctoral thesis, Universitat Autònoma de Barcelona, 2004. http://hdl.handle.net/10803/3368.
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Chilakamarri, Kiran Babu. „Rotating and stratified fluids /“. The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487584612163036.
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Chilcott, Mark David. „Mechanics of non-Newtonian fluids“. Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329946.
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Lee, Peter D. „Organometallic synthesis in supercritical fluids“. Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336862.
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Aloku, Gabriel Olayinka. „Dynamics of Foam Growth in Polymeric Fluids Flow“. Thesis, University of Manchester, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.532207.
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Haldenwang, Rainer. „Flow of non-newtonian fluids in open channels“. Thesis, Cape Technikon, 2003. http://hdl.handle.net/20.500.11838/1042.
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Dissertation (DTech (Civil Engineering))--Cape Technikon, Cape Town, 2003Flume design for homogeneous non-Newtonian fluids is problematic and not much research has been conducted in this field. This application is industrially important in mining where slurries have to be transported to processing or disposal sites at higher concentrations because water is becoming a scarce and expensive commodity. This thesis addresses the problem of flume design and develops predictive models for the laminar, transitional and turbulent flow behaviour of non-Newtonian fluids in rectangular open channels. The relevant literature pertaining to Newtonian and non-Newtonian pipe and open channel flow is reviewed and research aspects are identified. A unique test facility was designed, constructed and commissioned for this project. The facility includes a 5 m-long by 75 mm-wide rectangular tilting flume, as well as a 10 m by 300 mmwide rectangular tilting flume that can be partitioned to form a 150 mm wide flume. The flumes are in series with an in-line tube viscometer which has tubes of diameter 13, 28 and 80 mm. The experimental investigation covers a wide range of widths (75 mm-300 mm), slopes (1º-5º), flow rates (0.05 l/s-45 l/s), relative densities (1.0067-1.165), volumetric concentrations (0%-10%), and yield stresses (0-21.3 Pa). The fluids tested are kaolin and bentonite slurries and CMC and Carbopol polymer solutions. The resulting database of empirical flow behaviour enabled the identification of the important flow behaviour characteristics. Existing models are compared and evaluated using the experimental database compiled for this thesis and it is concluded that no model exists to predict the database compiled for the various materials from laminar flow through the transition region into turbulence. For the correlation of laminar flow data, a Reynolds number was developed from the Reynolds number proposed for pipe flow by Slatter (1994). Using this Reynolds number, all the laminar flow data available was collapsed onto the 16/Re line on a standard Moody diagram. Criteria were developed to predict the onset of transition and the onset of ‘full turbulence’. These criteria are functions of the Froude and Reynolds number as well as the viscous characteristics of the fluids. These models performed better than the methods proposed by Naik (1983) and Coussot (1994), which were based on the Hanks criterion. A turbulent flow model was developed based on the turbulent model presented by Slatter (1994) for pipe flow. Flow predictions using this model were more accurate than those presented by Torrance (1963), Naik (1983), Wilson and Thomas (1985), and Slatter (1994). The new models were tested with the database compiled for this thesis as well as with two published data sets, one by Naik (1983) and the other by Coussot (1994). The new flow models predicted all the available data within acceptable limits, providing a basis for design. A new and experimentally validated design protocol is presented for the design of rectangular non-Newtonian open channel flow in laminar, transitional and turbulent flow.
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Sande, Hilde. „The Cauchy problem for a model of immiscible gas flow with large data“. Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for matematiske fag, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5163.
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Boukili, Hamza. „Schémas de simulation d'un modèle à trois phases immiscibles pour application à l'explosion vapeur“. Thesis, Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0077.
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Dans ce travail, on étudie la modélisation d'écoulement à trois phases non miscibles. L'application visée est l'explosion vapeur, qui risque de se produire lorsqu'un constituant liquide (S) (métal liquide à haute température) rentre en contact avec un constituant relativement froid, qui est en général de l'eau présente sous forme liquide (L) et vapeur (V). Les principaux transferts ayant lieu sont de type dynamique (vitesse-pression) et thermodynamique (échanges de chaleur et de masse). Plus précisément, les transferts de chaleur apparaissent entre les phases S, L et V, tandis que le transfert de masse ne peut survenir qu'entre les phases L et V du constituant eau. Les applications de type explosion vapeur (EV) génèrent des ondes de choc se propageant au sein du milieu et allant impacter des structures. Il est essentiel de noter que les temps de simulation réels, et les échelles de temps, sont courts. Il s'agit donc de simuler un modèle d'EDP avec lois de fermeture, qui permette de traiter des écoulements fortement instationnaires à trois phases immiscibles, avec génération d'ondes de choc et forts transferts thermiques et de masse, et qui soit conforme au second principe de la thermodynamique. Une fois le modèle d'EDP fermé donné, l'attention est portée sur la méthode numérique d'approximation de ce modèle. Une stratégie à pas fractionnaires est mise en place, afin de permettre de traiter un à un les différents effets de relaxation inclus dans le modèle. Différents cas tests numériques ont été réalisés, afin de s'assurer des propriétés des schémas considérés, et valider la cohérence des résultats numériques avec le comportement physique attendu de l'écoulement simuléThis PhD work consists of modeling a three-phase flow: liquid (L), gas (V) for the same component (water) and solid (S) for a second component (high temperature metal). Such a mix is characterized by the risk of occurrence of vapour explosion, where major transfers happen: in this bi-component environment dynamic transfers are important (speed / pressure) and thermodynamic exchanges (heat and mass transfers) also are at stake. More specifically, heat transfers occur between phases S, L and V, while the mass transfer can only occur between the phases L and V. The vapour explosion type applications (EV) generate shock waves propagating within the medium and can impact the structures. Finally, it is essential to note that the actual simulation time, and different time scales are short. The mission is, therefore, to compute an EDP model with closure laws, capable of dealing with strongly unsteady three-phase non-miscible flows, with generation of shock waves and high thermal and mass transfer, and consistent with the second principle of thermodynamics. The second step is to propose a Finite Volume numerical method adapted to the approximation of this model, and in the presence of shock waves. Numerical test cases are given in order to verify the properties of the considered schemes, attention is paid to the consistency between the numerical results and the expected physical behavior of the simulated flow
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Alba, Kamran. „Displacement flow of complex fluids in an inclined duct“. Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44642.
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This thesis studies buoyant displacement flows with two miscible fluids in pipes and 2D channels that are inclined at an angle β measured from vertical changing from 0° to 90°. The focus is on inclination angles away from nearly horizontal since these flows are previously studied in full details in the literature. Detailed experimental, analytical and computational approaches are employed in an integrated fashion.
Both density stable (light fluid displacing heavy one) and density unstable (heavy fluid displacing light fluid) displacements are studied. For density stable flows the study is purely experimental in the limit of iso-viscous Newtonian fluids. The density stable configuration has been found to produce highly efficient displacements, with the bulk of the interface moving steadily at the mean velocity. The streamwise length of the stretched interface increases with the mean flow velocity, viscosity and inclination β from vertical, and decreases with density difference.
The rest of the thesis deals with density unstable configuration. From experimental point of view, the pipe displacement flows are studied for iso-viscous Newtonian and also viscoplastic fluids. In the Newtonian limit, completely different regimes than nearly-horizontal case are observed. As a first order approximation, different regimes are classified in a two-dimensional (Fr; Re cosβ/Fr plane) providing leading order correlations to transitions to different regimes. Similar regimes are found for channel geometry through numerical simulations of PELICANS code. For non-Newtonian fluids we have focused on industrially interesting cases of large yield stress fluids in the pipe. The two distinct flow regimes namely central-type and slump-type first observed in nearly horizontal angles were found to also persist over other inclinations. Completely new and exotic behaviors were also observed due to the effect of inclination angle and instabilities.
From mathematical and modeling point of view a two-layer weighted residual model for generalized Newtonian fluids has been developed. The model works for channel geometry and can be used to predict the displacement interface height, the front velocity and more importantly, the flow stability.
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Papenkort, Simon [Verfasser]. „Flow of yield-stress fluids through channels / Simon Papenkort“. Konstanz : Bibliothek der Universität Konstanz, 2013. http://d-nb.info/1047063174/34.
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Kandaiah, Nishani. „Flow splitting of rheologically complex fluids under complex conditions“. Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412537.
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LANE, MAURICIO. „FLOW OF NON-NEWTONIAN FLUIDS THROUGH CONVERGING-DIVERGING CHANNELS“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7613@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRONeste trabalho foi analisado o escoamento de fluidos não Newtonianos através de canais axisimétricos convergentes divergentes. A solução da conservação de massa e de conservação de momento foi obtida numericamente via volumes finitos utilizando o programa de computador Fluent. A equação constitutiva de fluidos Newtonianos generalizados foi utilizada para modelar o comportamento não Newtoniano, utilizando a equação constitucional de Shunk-Scriven para cálculo da viscosidade, que assume como sendo a média geométrica ponderada pelo classificador de escoamento R entre a viscosidade de cisalhamento e a viscosidade de extensão. Os resultados de perda de pressão e vazão são comparados com os resultados calculados pela relação simplificada proposta por Souza Mendes e Naccache, 2002 entre a perda de carga e vazão de fluidos viscoelásticos fluindo através do meio poroso, para analisar a sua performance.
In this work, the flow of non-Newtonian fluids through axisimmetric convergingdiverging channels is analyzed. The solution of mass and momentum conservation equations is obtained numerically via finite volume technique using the Fluent software. The Generalized Newtonian Fluid constitutive equation was used to model the non- Newtonian fluid behavior, using the Shunk-Scriven model for the viscosity, where a weighted geometric mean by the flow classifier R between shear and extensional viscosities is assumed. The results of pressure drop and flow rate are compared to the ones predicted by a previously proposed simplified relation (Souza Mendes and Naccache, 2002) between pressure drop and flow rate, for viscoelastic fluids flow through porous media, in order to analyze its performance.
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CANDELA, WILLIAM FERNANDO LOPEZ. „FLOW OF GAS BUBBLES IN VISCOPLASTIC AND THIXOTROPIC FLUIDS“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36094@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
O escoamento de gás em fluidos complexos é um fenômeno presente em industrias como alimentos e bebidas, farmacêutica, química e petróleo e gás. Nesta pesquisa foi abordado o fenômeno de invasão de gás em pastas de cimento durante o processo de cimentação de poços de petróleo. Este problema é governado por diferentes parâmetros como tamanho, geometria e velocidade das bolhas, reologia do fluido, histórico de cisalhamento do material, pressão e vazão de injeção. Neste trabalho estuda-se experimentalmente a dinâmica de uma bolha de ar não esférica em regime de Stokes ou laminar, escoando em materiais que simulam pastas de cimento com diferentes níveis de viscosidade. As pastas de cimento e suas propriedades viscoplásticas e tixotrópicas são reproduzidas usando suspensões de Carbopol e Laponita, respectivamente. Apresenta-se também um modelo matemático simplificado para a dinâmica do fenômeno de migração de gás, com aplicação na indústria do petróleo. No estudo com Carbopo, investiga-se o efeito da tensão limite de escoamento e a relação entre forças viscosas e inerciais, e sua influência na dinâmica e na geometria da bolha de gás. A análise com Laponita visa simular o processo de invasão e migração de gás durante o processo de cura do cimento. O efeito da tixotropia no formato e na dinâmica de migração das bolhas é analisado. Estes resultados simulam também a complexa dinâmica da migração de gás em fluidos com reologia dependente do tempo, como as pastas de cimento ao longo de seu processo de cura. Observou-se a formação de bolhas de gás com geometria plana, que permitem o escoamento com baixa resistência e formam caminhos preferenciais, que podem se tornar canais de escoamento de gás a alta vazão.
The gas flow in complex fluids is a phenomenon present in industries such as foods and beverage, pharmaceuticals, chemistry and oil and gas. In this research the phenomenon of gas invasion in cement pastes during the cementation process of wells of petroleum was analyzed. This problem is governed by different parameters such as bubble size, geometry and velocity, fluid rheology, material shear history, injection pressure and flow rate. In this work, we perform an experimental study of the dynamics of a non-spherical air bubble under a Stokes or laminar regime, flowing in materials that simulate cement pastes with different levels of viscosity. Cement pastes and their viscoplastic and thixotropic properties are reproduced using suspensions of Carbopol and Laponite, respectively. A simplified mathematical model for the dynamics of the phenomenon of gas migration, with application in the petroleum industry, is also presented. In the Carbopol study, the effect of the yield stress and the relationship between viscous and inertial forces and their influence on the dynamics and geometry of the gas bubble is investigated. The analysis with Laponite aims to simulate the process of invasion and gas migration during the cement cure process. The effect of thixotropy on the shape and dynamics of bubble migration is analyzed. These results also simulate the complex dynamics of gas migration in fluids with time dependent rheology, such as cement pastes during their curing process. The formation of gas bubbles with flat geometry has been observed, allowing the gas to flow with lower resistance and to form preferred paths that can become channels with high gas flow rates.