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1
Lombe, Mubanga. "Spin coating of Newtonian and non-Newtonian fluids." Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4904.
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Aguilar-Martinez, Silvestre. "Critical collapse of Newtonian fluids." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54754.
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This thesis constitutes a numerical study concerning the dynamics of an inviscid
fluid subject to Newtonian gravity. Type-II critical phenomena has been previously measured in gravitational collapse simulations of isothermal-gas-spheres in Newtonian gravity. Our first objective was to extend this work by applying the more general polytropic-gas equation-of-state to the spherically symmetric fluid. We showed that under generic conditions of critical collapse, the polytropic gas allows for scale-invariant solutions. These solutions display self-similarity of the first kind with non-linear scaling between the space and time variables. One of these solutions was identified as the critical solution in critical collapse simulations. Such solution was found to have a single unstable mode with a Lyapunov exponent whose value depends on the polytropic index (Γ) from the equation of state. We argued that this behavior constitutes evidence of type-II critical phenomena with a transition from type-II to type-I behavior occurring at Γ ≥ 6/5. Thus, the polytropic gas exhibits both types of critical behavior. These phenomena was investigated dynamically and also from perturbation analysis. In the second phase of the project we extended the hydrodynamic model to treat
axi-symmetric gravitational collapse. This allowed us to study the effect of angular momentum on the critical solution. As previously predicted, infinitesimal initial rotation introduces a non-spherical, unstable axial mode into the dynamics. The measured scaling behavior of the specific angular momentum of the collapsed core agrees with the predicted growth rate (Lyapunov exponent) of the axial perturbation. This two-mode linear regime modifies the scaling laws via the introduction of universal functions that depend on the two-parameter family of initial data. The predicted universality of these functions was confirmed through careful measurements of the collapsed mass and its angular momentum near the collapse threshold. A two-parameter space survey reveals a universal behavior of the order-parameters, with no mass-gap even in the presence of finite initial rotation. The behavior changes slightly beyond some initial rotation threshold. The results then, can be interpreted as an intermediate convergence to a non-spherical self-similar critical solution with a single unstable mode.Science, Faculty of
Physics and Astronomy, Department of
Graduate
3
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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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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Ozgen, Serkan. "Two-layer flow stability in newtonian and non-newtonian fluids." Doctoral thesis, Universite Libre de Bruxelles, 1999. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211876.
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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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Chaffin, Stephen. "Non-Newtonian fluids in complex geometries." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16750/.
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Whitelaw, David Stuart. "Droplet atomisation of Newtonian and non-Newtonian fluids including automotive fuels." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266620.
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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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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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Cunha, Evandro Fernandes da. "Implementação de aparato experimental para medição de instabilidades tipo Roll Waves em fluidos não- newtonianos /." Ilha Solteira, 2013. http://hdl.handle.net/11449/124473.
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Orientador: Geraldo Maciel de FreitasCo-orientador: Cláudio Kitano
Banca: Elaine Maria Cardoso
Banca: José Junji Ota
Resumo: Esta dissertação de mestrado faz uma abordagem do trabalho experimental desenvolvido no âmbito de pesquisa de escoamento de fluidos não-newtonianos em canais inclinados. Quando estes escoamentos são colocados em condições favoráveis de inclinação e vazão, pode-se constituir um domínio propício à propagação de instabilidades na superfície livre que, eventualmente, podem evoluir para um tipo específico de ondas, conhecidas na literatura como roll waves. Estas ondas, de comprimento e amplitude bem definidos, são especialmente afetadas pelas características do escoamento e do fluido. Em termos de fluido teste, foi confeccionado, caracterizado reologicamente e utilizado o gel de carbopol, de base polimérica e de propriedade não-newtonianas, com bom ajuste do modelo reológico de Herschel-Bulkley. Como existe na literatura uma grande lacuna no que diz respeito a medidas deste fenômeno tanto na natureza quanto em laboratório, buscou-se neste trabalho, projetar e construir um aparato experimental que fosse capaz de reproduzir as condições necessárias para a geração de roll waves, em condições controladas. Técnicas fotométricas e ultrassônicas foram utilizadas no experimento para aferir informações de altura de escoamento, após o fluido teste (gel de carbopol) ser perturbado, por um sistema específico projetado para este fim. O aparato experimental desenvolvido permite, doravante, simulações de roll waves em diversos cenários para fluidos de reologia diversa, constituindo assim, um suporte de grande valia ao entendimento e controle de roll waves presentes, por exemplo em corridas de lama
Abstract: This dissertation makes an approach to the experimental work carried out within the research of non-Newtonian fluids drained in inclined channels. When these flows are placed in favorable slope and flow, can be a suitable area to the spread of instability at the free surface which may eventually evolve into a specific type of waves, known in the literature as "roll waves". These waves of well- defined length and amplitude are especially affected by the flow characteristics and the fluid. In terms of fluid test was elaborated, rheologically characterized and used carbopol gel, polymer-based and non-Newtonian property, with good adjustment of the rheological model of Herschel-Bulkley. As there is a big gap in the literature regarding to both measures of this phenomenon in nature as in the laboratory, was sought in this work, the formation of an experimental apparatus that was able to reproduce the necessary conditions for the generation of roll waves in the laboratory, under those controlled conditions. Photometric and ultrasonic techniques were used in the experiment for measuring height information of the flow after the test fluid (carbopol gel) being disturbed by a specific system designed for this purpose. The experimental apparatus developed now enables simulations of roll waves in various scenarios for different fluid rheology, is thus an invaluable support to the understanding and control of this "roll waves" present in mud, for example
Mestre
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Stocks, Marc Darren. "Geometric optimisation of heat transfer in channels using Newtonian and non-Newtonian fluids." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/33348.
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The continual advance in manufacturing processes has resulted in significantly more compact, high performance, devices. Consequently, heat extraction has become the limiting factor, and of primary concern. Therefore, a substantial amount of research has been done regarding high efficiency micro heat exchangers, employing novel working fluids.
This dissertation numerically investigated the thermal behaviour of microchannel elements cooled by Newtonian and non-Newtonian fluids, with the objective of maximising thermal conductance subject to constraints. This was done, firstly, for a two-dimensional simple microchannel, and secondly, for a three-dimensional complex microchannel. A numerical model was used to solve the governing equations relating to the flow and temperature fields for both cases. The geometric configuration of each cooling channel was optimised for Newtonian and non-Newtonian fluids, at a fixed inlet velocity and heat transfer rate. In addition, the effect of porosity on thermal conductance was investigated.
Geometric optimisation was employed to the simple and complex microchannels, whereby an optimal geometric ratio (height versus length) was found to maximise thermal conductance. Moreover, analysis indicated that the bifurcation point of the complex microchannel could be manipulated to achieve a higher thermal conductance.
In both cases, it was found that the non-Newtonian fluid characteristics resulted in a significant variation in thermal conductance as inlet velocity was increased. The ii
characteristics of a dilatant fluid greatly reduced thermal conductance on account of shear-thickening on the boundary surface. In contrast, a pseudoplastic fluid showed increased thermal conductance.
A comparison of the simple and complex microchannel showed an improved thermal conductance resulting from greater flow access to the conductive area, achieved by the complex microchannel.
Therefore, it could be concluded that a complex microchannel, in combination with a pseudoplastic working fluid, substantially increased the thermal conductance and efficiency, as opposed to a conventional methodology.Dissertation (MEng)--University of Pretoria, 2012.
gm2014
Mechanical and Aeronautical Engineering
unrestricted
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Smieszek, Marlene. "Structures and stability of Newtonian and non-Newtonian fluids in Taylor-Couette system /." Düsseldorf : VDI-Verl, 2008. http://d-nb.info/990760308/04.
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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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Wilson, Lynda M. Z. "Controllability of Non-Newtonian fluids under homogeneous flows." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5FWilson%5FLynda.pdf.
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Thesis (M.S. in Applied Mathematics)--Naval Postgraduate School, September 2007.Thesis Advisor(s): Zhou, Hong. "September 2007." Description based on title screen as viewed on October 25, 2007. Includes bibliographical references (p. 47). Also available in print.
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Grenville, R. K. "Blending of viscous Newtonian and pseudo-plastic fluids." Thesis, Cranfield University, 1992. http://hdl.handle.net/1826/4362.
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Blend times and power consumption have been measured for Newtonian and pseudo-
plastic fluids in agitated, baffled vessels with diameters of 0.30,0.61 and 1.83 m. The
viscosities of the fluids were selected to give a range of Reynolds numbers between 200
and 105. Four impellers were tested with diameters between T/3 and T/2 positioned at
T/3 clearance above the lowest point of the vessel base. The impellers were typical of
those found in the chemical industry.
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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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Berti, Stefano. "Non-Newtonian turbulence : viscoelastic fluids and binary mixtures." Nice, 2006. http://www.theses.fr/2006NICE4079.
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Cette thèse présente une étude théorique et numérique de la turbulence dans les fluides non-Newtoniens, dont la dynamique peut être modélisée en termes du transport de champs actifs et c’est un sujet d’intérêt général pour la physique des fluides complexes. Leur rhéologie particulière les rend, en outre, intéressants pour des applications en ingénierie. La plus grande partie du travail regarde les solutions diluées de polymères. Deux aspects sont considérés : la statistique aux petites échelles, pour des élasticités modérées dans un régime de turbulence développée ; la déstabilisation d’un écoulement par non linéarités élastiques. L’effet des polymères sur les petites échelles turbulentes est étudié avec un modèle simplifié de fluide viscoélastique, en conditions d’isotropie et homogénéité. Les changements de la cascade turbulente sont considérés, et leurs conséquences pour la statistique à petite échelle sont examinées. Dans la limité opposée de non linéarités inertielles négligeables, les degrés de liberté polymériques peuvent déstabiliser un écoulement, quand l’élasticité de la solution est assez élevée. En augmentant l’élasticité on observe une transition vers des états « turbulents ». La phénoménologie expérimentale est reproduite numériquement et les propriétés statistiques sont caractérisées. Un autre sujet considéré est celui des mélanges binaires. On examine la séparation de phase entre deux fluides en présence d’un champ de vitesse forcé. On analyse la compétition entre les forces thermodynamiques et les cisaillements locaux, dans des mélanges actifs et passifs, et on souligne le rôle marginal du chaos Lagrangien pour le phénomène de l’arrêt de la mise en ordreThis thesis presents a theoretical and numerical study of turbulence in non-Newtonian fluids. The dynamics of these systems can be modelled in terms of transported active fields and constitutes a subject of general interest in complex fluid’s physics. Their peculiar rheological properties make them attractive also for engineering applications. The major part of the work concerns turbulence in dilute polymer solutions, i. E. Viscoelastic fluids. Two issues are considered : the small-scale statistics at moderate values of elasticity in a fully developed turbulence regime ; the destabilization of a laminar flow by means of purely elastic non linearities. The effect of polymers on small-scale turbulence has been studied in a simplified viscoelastic fluid model, in a homogeneous isotropic configuration. The modifications on the turbulent cascade have been addressed, as well as their consequences on small-scale statistics. In the opposite limit of negligible inertial non linearities, polymeric degrees of freedom can destabilize a flow, when the elasticity of the solution is large enough. At growing elasticity, a transition to chaotic, and turbulent, states is observed. The experimental phenomenology has been numerically reproduced and statistical properties have been characterized. Another item considered is that of binary mixtures. Phase separation between two fluids has been investigated in presence of an externally forced velocity field. The competition between thermodynamic forces and local shears has been examined in both active and passive mixtures and the marginal role of Lagrangian chaos in the phenomenon of coarsening arrest has been highlighted
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Singh, Brajesh Kumar. "Flow of Newtonian and non-Newtonian fluids in porous media, the viscous fingering instability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/MQ49685.pdf.
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Amiri, Amin. "Buoyant miscible displacement flows of Newtonian and non-Newtonian fluids : stationary and oscillating geometries." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/36974.
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Cette thèse vise l’étude des écoulement de déplacement de fluides miscibles à l’intérieur d’un long tuyau stationnaire vertical et d’un tuyau en mouvement. Concernant la géométrie des mouvements, le tuyau oscille comme un pendule inversé avec une fréquence maximale faible, c’est-à-dire, ˆf= 0.2(Hz) et une oscillation maximale de faible amplitude, soit 15 (◦) par rapport à l’axe du tuyau. Les écoulement de déplacement se produisent à un nombre de Péclet élevé et aux petits nombres d’Atwood. L’accent est mis sur les types de fluides et de géométries (tuyau fixe ou en mouvement). Les approches expérimentales détaillées sont utilisées de manière intégrée. Dans cette thèse, la configuration de densité est la densité instable. La majeure partie des travaux en cours se concentre sur les écoulements de déplacement de fluides Newtoniens isovisqueux, mais nous étudions également l’écoulement de déplacement à contrainte au seuil de plasticité dans un long tuyau vertical. Pour un écoulement de déplacement Newtonien isovisqueux dans un tuyau stationnaire, nous remarquons un effet stabilisant imposé au débit principal et signalant l’existence de deux régimes d’écoulement principaux à long moment introduits par un écoulement de déplacement stable et un écoulement de déplacement instable. La transition entre ces deux régimes se produit à un nombre critique de Reynolds modifié (RetThis thesis aims to investigate buoyant displacement flows of miscible fluids in a long, vertical stationary pipe or a moving pipe. For the case of the moving geometry, the pipe oscillates like an inverted pendulum with a small maximum frequency, i.e.ˆf= 0.2(Hz) and a small maximum oscillation amplitude, i.e. 15 (◦) with respect to the pipe axis. The displacement flows occur at the high Péclet number and small Atwood numbers. The focus is on the type of fluids and geometries (stationary or moving pipe). Detailed experimental approaches are employed in an integrated fashion. The density configuration in this thesis is the density unstable. The main part of the current work is concentrated on displacement flows of iso-viscous Newtonian fluids. We also study the yield stress displacement flow in a long vertical pipe. For iso-viscous Newtonian displacement flow in a stationary pipe, we uncover the stabilizing effect of the mean imposed flow and report the existence of two main flow regimes at long times introduced as a stable displacement flow and an unstable displacement flow. The transition between these two regimes occurs at a critical modified Reynolds number (Ret
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Kazadi, Dieudonne Matang'a. "Non-Newtonian losses through diaphragm valves." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/904.
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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2005The prediction of head losses in a pipe system is very important because head losses affect the performance of fluid machinery such as pumps. In a pipe system, two kinds of losses are observed: major losses and minor losses. In Newtonian and non-Newtonian flow, major losses are those that are due to friction in straight pipes and minor losses are those that are due to pipe fittings such as contractions, expansions, bends and valves. Minor losses must be accurately predicted in a pipe system because they are not negligible and can sometimes outweigh major losses (Edwards et al., 1985). There is presently little data for the prediction of non-Newtonian head losses in pipe fittings in the literature and little consensus amongst researchers (Pienaar et al., 2004). In the case of diaphragm valves, usually, only one loss coefficient value is given in turbulent flow or in laminar flow with no reference to a specific size of the valve, assuming geometrical similarity that would lead to dynamic similarity. However, no one has done a systematic study of various sizes of diaphragm valves from the same manufacturer to establish if this is true. This could be the main reason for discrepancies found in the literature (Hooper, 1981; Perry & Chilton, 1973; Miller, 1978 and Pienaar et al., 2004). This work addresses this issue. A literature revIew on the flow of Newtonian and non-Newtonian fluids has been presented. The work of Hooper (1981) on diaphragm valves and the works of Edwards et al., (1985), BaneIjee et aI., (1994) and Turian et al., (1997) for non-Newtonian fluids in globe and gate valves were found to be relevant to this work.
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Cunha, Evandro Fernandes da [UNESP]. "Implementação de aparato experimental para medição de instabilidades tipo Roll Waves em fluidos não- newtonianos." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/124473.
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000836682.pdf: 2242597 bytes, checksum: 64204d0074211d1723d7ad5c6f876572 (MD5)Esta dissertação de mestrado faz uma abordagem do trabalho experimental desenvolvido no âmbito de pesquisa de escoamento de fluidos não-newtonianos em canais inclinados. Quando estes escoamentos são colocados em condições favoráveis de inclinação e vazão, pode-se constituir um domínio propício à propagação de instabilidades na superfície livre que, eventualmente, podem evoluir para um tipo específico de ondas, conhecidas na literatura como roll waves. Estas ondas, de comprimento e amplitude bem definidos, são especialmente afetadas pelas características do escoamento e do fluido. Em termos de fluido teste, foi confeccionado, caracterizado reologicamente e utilizado o gel de carbopol, de base polimérica e de propriedade não-newtonianas, com bom ajuste do modelo reológico de Herschel-Bulkley. Como existe na literatura uma grande lacuna no que diz respeito a medidas deste fenômeno tanto na natureza quanto em laboratório, buscou-se neste trabalho, projetar e construir um aparato experimental que fosse capaz de reproduzir as condições necessárias para a geração de roll waves, em condições controladas. Técnicas fotométricas e ultrassônicas foram utilizadas no experimento para aferir informações de altura de escoamento, após o fluido teste (gel de carbopol) ser perturbado, por um sistema específico projetado para este fim. O aparato experimental desenvolvido permite, doravante, simulações de roll waves em diversos cenários para fluidos de reologia diversa, constituindo assim, um suporte de grande valia ao entendimento e controle de roll waves presentes, por exemplo em corridas de lama
This dissertation makes an approach to the experimental work carried out within the research of non-Newtonian fluids drained in inclined channels. When these flows are placed in favorable slope and flow, can be a suitable area to the spread of instability at the free surface which may eventually evolve into a specific type of waves, known in the literature as roll waves. These waves of well- defined length and amplitude are especially affected by the flow characteristics and the fluid. In terms of fluid test was elaborated, rheologically characterized and used carbopol gel, polymer-based and non-Newtonian property, with good adjustment of the rheological model of Herschel-Bulkley. As there is a big gap in the literature regarding to both measures of this phenomenon in nature as in the laboratory, was sought in this work, the formation of an experimental apparatus that was able to reproduce the necessary conditions for the generation of roll waves in the laboratory, under those controlled conditions. Photometric and ultrasonic techniques were used in the experiment for measuring height information of the flow after the test fluid (carbopol gel) being disturbed by a specific system designed for this purpose. The experimental apparatus developed now enables simulations of roll waves in various scenarios for different fluid rheology, is thus an invaluable support to the understanding and control of this roll waves present in mud, for example
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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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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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Baloch, A. "Numerical simulation of complex flows of non-Newtonian fluids." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636028.
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A finite element study of incompressible isothermal complex flows of Newtonian and non-Newtonian fluids is presented. The aim of this investigation is to analyse through a numerical technique the non-viscometric flow behaviour of non-Newtonian fluids. The fluid properties are defined utilising various constitutive equations. A semi-implicit Taylor-Galerkin/pressure-correction algorithm is employed to solve Newtonian, generalised inelastic non-Newtonian and fibre suspension flows. A modified Taylor-Galerkin scheme is presented for viscoelastic flows incorporating a consistent streamline upwind Petrov-Galerkin technique for the stress equations. The numerical algorithm is based on a time-marching procedure and a pressure-correction method that introduces multiple solution stages over each time step. The reported results demonstrate the significant influence of inertia on flow development in both converging and diverging flows. Through a study of two and three dimensional flows of Newtonian and viscoelastic fluids through planar expansions it has been possible to draw conclusions concerning the effects of the expansion ratio and the impact of the third spatial dimension. This demonstrates the appearance of lip vortices and subsequently vortex enhancement. Also the influence of the viscoelasticity on flow development is investigated and gives rise to a die-swell effect. Also considered are simulations for viscoelastic planar contraction flows, strain-thickening in extensional flow or abrupt and rounded re-entrant corner axisymmetric circular contractions and fibre suspension planar and axisymmetric circular contraction flows. In particular the influence and interaction between inertia and extensional viscosity are investigated on both flow development and pressure drop that results in transition between lip and salient corner vortices with twin centres and subsequently vortex enhancement. The impact of rigid rod-like fibres is clearly marked on flow structure in both converging and diverging flows.
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Childs, Laura Helen. "Low Reynolds number flows of generalized non-Newtonian fluids." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633090.
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A Newtonian fluid is one for which the stress induced by flow is proportional to the strain rate, with the constant of proportionality being the fluid's viscosity. Fluids not adhering to this linear relationship are described as non-Newtonian. This thesis considers several problems involving flows of generalized non-Newtonian fluids - where the effective viscosity is a nonlinear function of the strain rate - experiencing negligible inertial effects. First, we consider the flow of a power-law fluid through a rectangular duct. We propose a numerical method of solution, reliant on expressing the governing equations in terms of the stress tensor components, rather than the velocity field. This results in an effective method of determining the flux of fluid through a cross-section of a duct. The calculation is extended to duct flows of regularized Herschel-Bulkley fluids, and the determination of the critical yield stress below which there is no flow. We then consider free-surface dam-break flows of power-law fluids. By utilizing a similarity scaling for the front position of the flow with time, the flux calculation of the preceding work, and laboratory experiments, we propose a method of determining the rheological parameters of a power-law fluid. The settling velocity of a spherical particle through a power-law fluid is next examined. For particles settling within a background shear flow, the settling velocity is found to have two distinct dependencies on the dimensionless flow parameters, corresponding to regimes of dominant background shear or gravitational settling. Finally, we consider the effect that a modified sedimentation law, based upon the results of the settling calculation, has on shear flows of dilute particulate suspensions. The method of characteristics is applied to investigate the sedimentation law's impact on properties such as the concentration profile, and run-out length, of a sustained intrusion of particles suspended in a power-law fluid.
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Tonkin, Ruth Julie Jane. "Swirling pipeflow of non-Newtonian and particle-laden fluids." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/11673/.
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This thesis describes the application of novel swirl inducing pipe to various pipe configurations, when pumping a range of fluids and fluid / particle mixtures. An extensive experimental programme, incorporating particle image velocimetry and photography, was implemented using a pipe flow loop designed specifically for the purpose. Experimental data was obtained on the effect of a 4-lobe near-optimal swirl pipe on coal-water, sand-water and magnetite-water slurries of various particle size. Results indicated that swirl induction produced greater benefit for denser slurries and higher concentrations, and that swirl induced into slurries containing larger and denser particles decayed more rapidly. At low velocity, experimental data highlighted a reduction in the total pressure drop experienced across a 3.0m horizontal pipe section, a downward sloping section and vertical pipe bends, when the swirl-inducing pipe was present. PIV was used to measure the axial and tangential velocity of swirling flows downstream of a near-optimal swirl-inducing pipe. It was confirmed that a significant tangential velocity was generated when pumping water in the turbulent regime, however, when the fluid viscosity was increased, leading to laminar flow, no significant tangential velocity was detected.
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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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Redmon, Jessica. "Stochastic Bubble Formation and Behavior in Non-Newtonian Fluids." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case15602738261697.
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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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Mernone, Anacleto Valentino. "A mathematical study of peristaltic transport of physiological fluids." Title page, contents and summary only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phm566.pdf.
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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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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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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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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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Kabwe, Aime Mume. "Non-newtonian loss coefficient for Saunders diaphragm valves /." [S.l. : s.n.], 2009. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1008&context=td_cput.
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Ashur, Dor Yisrael. "The effects of non-Newtonian fluids on Purcell's Scallop Theorem." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/fullcit?p1477882.
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Thesis (M.S.)--University of California, San Diego, 2010.Title from first page of PDF file (viewed July 13, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (leaf 50).
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Varagnat, Matthieu. "Instabilities of jets of non-Newtonian fluids impacting a plate." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44324.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (p. 106-111).
The problem of buckling and coiling of jets of viscous, Newtonian liquids impacting a plate has received a substantial level of attention over the past two decades, both from experimental and theoretical points of view. Nevertheless, most industrial and everyday life fluids are non-newtonian, and their rheological properties affects their behavior in this problem. The present work aims at studying the instabilities of jets of such fluids falling on a plate, via both phenomenological descriptions and theoretical analysis of jet motion and shape. Several fluids with different rheological properties, including viscous Newtonian oil, model non-Newtonian fluids, and commercial shampoos, are used and different dynamical regimes are documented. A special focus is placed on viscoelastic, shear-thinning cetylpyridinium (CPyC1) solutions. In concentrated solutions, CPyCl surfactant molecules have been shown to assemble in long wormlike micellar structures, which gives the fluid its non-Newtonian properties. Jets of CPyCl solution show several novel shapes and dynamical regimes not observed in the case of Newtonian fluids. The present study provides quantitative experimental measurements and mechanisms for these novel features.
by Matthieu Varagnat.
S.M.
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Ireka, Ikenna Ebubechukwu. "Computational analysis of non-isothermal flow of non-Newtonian fluids." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15590.
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The dynamics of complex fluids under various conditions is a model problem in bio-fluidics and in process industries. We investigate a class of such fluids and flows under conditions of heat and/or mass transfer. Experiments have shown that under certain flow conditions, some complex fluids (e.g. worm-like micellar solutions and some polymeric fluids) exhibit flow instabilities such as the emergence of regions of different shear rates (shear bands) within the flow field. It has also been observed that the reacting mixture in reaction injection molding of polymeric foams undergoes self-expansion with evolution of heat due to exothermic chemical reaction. These experimental observations form the foundation of this thesis. We explore the heat and mass transfer effects in various relevant flow problems of complex fluids. In each case, we construct adequate mathematical models capable of describing the experimentally observed flow phenomena. The mathematical models are inherently intractable to analytical treatment, being nonlinear coupled systems of time dependent partial differential equations. We therefore develop computational solutions for the model problems. Depending on geometrical or mathematical complexity, finite difference or finite volume methods will be adopted. We present the results from our numerical simulations via graphical illustrations and validate them (qualitatively) against' similar' results in the literature; the quotes being necessary in keeping in mind the novelties introduced in our investigations which are otherwise absent in the existing literature. In the case where experimental data is available, we validate our numerical simulations against such experimental results.
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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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Samanta, Devranjan [Verfasser], and Christian [Akademischer Betreuer] Wagner. "Transition to turbulence in pipe flow of Newtonian and Non Newtonian fluids / Devranjan Samanta. Betreuer: Christian Wagner." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1052953999/34.
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Dawson, Matthew A. (Matthew Aaron) 1983. "Modeling the dynamic response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44750.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references.
Engineering cellular solids, such as honeycombs and foams, are widely used in applications ranging from thermal insulation to energy absorption. Natural cellular materials, such as wood, have been used in structures for millennia. However, despite their extensive use, a comprehensive understanding of the dynamic interaction between the interstitial fluid in the cells of the foam and the foam itself has yet to be developed. In this thesis, we explore the dynamic, compressive response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids. To develop tractable analytical models for this complex, non-linear phenomenon, a study is first undertaken on the permeability of foam under deformation. Using these results, a model is developed for the dynamic, uniaxial compressive response of low-density, reticulated, elastomeric foam filled with a viscous Newtonian fluid. This comprehensive model is found to be well approximated by a simpler model, based on the lubrication approximation. Furthermore, in the lubrication limit, a model for the dynamic, uniaxial compressive response of foam filled with a non-Newtonian fluid is also developed. All of the models presented in this thesis are supported by extensive experimental studies. The experiments also suggest that these models are applicable over a wide-range of parameters, such as strain, strain rate, and pore size. Finally, these models are used in two case studies to assess the feasibility of composite structures containing a layer of liquid-filled foam in dynamic loading applications. The first case study focuses on applications in energy absorption with the experimental design of a motorcycle helmet. The second case study focuses on applications in mitigating the effects of blast waves with a parametric study of the design of a blast wall.
(cont.) These studies provide insight into the usefulness of the models and demonstrate that composite structures with a layer of liquid-filled foam have enormous potential in a wide range of dynamic loading applications.
by Matthew A. Dawson.
Ph.D.
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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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Perrin, Christian. "Experimental validation of pore network modelling at the Darcy and micro scales for Newtonian and non-Newtonian fluids." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2090.
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In this work, we used a combination of experimental techniques in order to validate pore network modelling' at both Darcy and pore scale. The pore networks were etched on a silicon wafer, and comprised 28202 rectangular capillaries 200 ~m long and 40 ~m deep, with two different capillary width distributions.' Flow experiments were perfonned with water as a model Newtonian fluid and shear-thinning partially hydrolyzed polyacrylamide (HPAM) polymer solution as the model non-Newtonian fluid. An original method was proposed in order to implement in the simulator the Carreau mod~l as the constitutive equation of the . shear-thinning fluid. Darcy scale experiments consiste~. in measuring pressure gradient between pore network inlet and outlet at different constant flow rates. Thus, an 'apparent' rheogram of the fluid was experimentally achieved. Quantitative agreement is seen between the experiments and the network calculations for both Newtonian and shear-thjnning regimes. However, at high ...../. flow rates HPAM exhibit a shear-thickening regime due to elastic effects that are not incorporated in the network model. Microscopic flow behaviour in the capillaries was visualized by using micro particle image velocimetry (~PIV) technology. This enables us to measure the velocity profile in the capillaries ~with a one micron resolution. An original method was developed to allow us to compare the computed mean velocity and the experimentally measured maximum velocity. Good correlations wer'~ found both in Newtonian and shear-thinning regime. Once the HPAM solution enters the shear-thickening regime, there is a marked increase in the amount . , of scatter observed in individual network ducts. More detailed IlP1V measurements of the micro flows in several 'neighboring channels show that asymmetric streamline patterns have been observed indicating that the effects of 'feeder' channels are leading to a very extensive 'inlet effect' as is often observed for extensional flows. The thesis is the first to present such a detailed analysis of both the Darcy scale rheology and the detailed micro-flow field using both experiment (etched silicon micromodels along with ~PIV) and pore scale network modelling. Comparison between experiment and theory shows a very interesting level of agreement.
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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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Geurts, Kevin Richard. "Stochastic simulation of non-Newtonian flow fields /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/9821.
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Toniati, André Luis. "Escoamentos pulsantes com superfície livre : caracterização e sua ação em fundo de canais /." Ilha Solteira, 2018. http://hdl.handle.net/11449/155857.
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Orientador: Geraldo de Freitas MacielResumo: No contexto de Desastres "Naturais", as corridas de lama têm sido objeto de estudo devido ao seu poder erosivo e, muitas vezes, destrutivo, acarretando perdas materiais vultosas e ceifando vidas. Nestes escoamentos, quando em condições favoráveis de vazão, inclinação e reologia do fluido, podem surgir instabilidades que se propagam em forma de trem de ondas na superfície, denominadas roll waves. A literatura acerca do assunto trata, geralmente, dos critérios de geração, estabilidade, e determinação das características principais do fenômeno, como amplitude, comprimento e celeridade de onda. Nesta dissertação buscou-se estudar a tensão de cisalhamento no fundo na presença de roll waves, em duas vertentes: a primeira apresenta as roll waves em água limpa, baseando-se no trabalho clássico de Dressler (1949); a segunda, dando continuidade aos trabalhos do Grupo de Pesquisa de Reologia de Materiais Viscosos e Viscoplástcos (Grupo RMVP), focou no estudo de roll waves desenvolvendo-se em fluidos do tipo Herschel-Bulkley, em duas situações - canal de fundo impermeável e fundo com condição de permeabilidade, grande contribuição desta dissertação. Os modelos matemáticos foram desenvolvidos com base nas equações de águas rasas, cuja implementação numérica permitiu confrontar resultados experimentais e numéricos, que apresentaram boa aderência. Para o modelo com condição de permeabilidade no fundo, verificou-se a influência do fator de porosidade nas características das roll waves (ampli... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Mudflows have been the focus of studies because of their erosive ability and often destructive power, causing material losses and taking away lives. Under favorable conditions of discharge, slope, disturbance, and rheology, these flows can develop a specific type of instability that is propagated downstream as shock waves, called roll waves. Most of the roll waves literature provides information on generation criteria, stability, and information of amplitudes, wavelengths, and celerity. This works brings a study of bottom shear stress in pulsating flows (roll waves) in 2 parts. In the first part, we present roll waves in clean water, based on Dressler’s work. In the second part, we continue the works of research team about roll waves developing in Herschel-Bulkley fluid under 2 conditions: impermeable bottom and porous bed. The mathematical models developed were based on shallow water equations. The results of these models were compared to Fluent and experimental results, showing a good agreement. For the mathematical model with porous bed condition, we evaluated the effect of porosity factor in properties of roll waves, and we observed that the amplitude of the roll wave usually increases, whereas the length and the celerity decrease with the presence of this factor. Finally, considering an impermeable bottom, the bottom shear stress presented an increase of 12% to 27%, depending on nature (laminar-turbulent) and dynamics (Froude number) of flow. Taking in account a porous b... (Complete abstract click electronic access below)
Mestre
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Presti, Felice. "Investigation of transitional and turbulent pipe flow of non-Newtonian fluids." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399138.
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Kealy, Timothy James. "Heat and momentum transfer to non-Newtonian fluids in annular ducts." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285277.
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