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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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Keiller, Robert A. "Non-Newtonian extensional flows". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315030.
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Hockey, Randal Myles. "Turbulent Newtonian and non-Newtonian flows in a stirred reactor". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46341.
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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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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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Mansour, Mohamed Hassan. "Non-Newtonian flow in microvessels". Thesis, University of Southampton, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523205.
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Fyrippi, Irene. "Flowmetering of non-Newtonian liquids". Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400185.
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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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Poole, Robert John. "Turbulent flow of Newtonian and non-Newtonian liquids through sudden expansions". Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399176.
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KONGARA, VEERA VENKATA SATYA SRINIVASU. "NONLINEAR STABILITY ANALYSIS OF VISCOUS NEWTONIAN AND NON-NEWTONIAN VISCOELASTIC SHEETS". University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1163617690.
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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.
12
Ross, Andrew Baxter. "Studies in non Newtonian coating flows". Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248600.
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ABDU, ALINE AMARAL QUINTELLA. "NON-NEWTONIAN FLUID DISPLACEMENT IN ANNULI". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29332@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Na indústria do petróleo são comuns processos envolvendo deslocamentos de um fluido pelo outro, como nos processos de completação e cimentação de poços. A eficiência desses deslocamentos é de suma importância, garantindo a vida útil do poço. A operação é considerada adequada quando ocorre uma distribuição homogênea da pasta de cimento na parede do poço. No presente trabalho um estudo experimental e numérico do deslocamento de fluidos em espaço anular foi realizada. Para os testes experimentais um simulador físico de um poço em escala foi construído. As equações de conservação de massa e momento foram resolvidas através do método de volumes finitos, utilizando os programas Fluent e OpenFOAM. Para a modelagem multifásica foi utilizado o método volume-of-fluid (VOF). No estudo, a avaliação da influência de parâmetros reológicos, razões de densidade e viscosidade, geometria do poço e vazão de bombeio foi realizada com o objetivo de otimizar o processo de cimentação. Os fluidos utilizados foram fluidos modelos e reais, newtonianos e não newtonianos. A eficiência de deslocamento foi avaliada através da configuração da interface entre os fluidos e através da determinação do da densidade da mistura na saída do anular ao longo do tempo.
Displacement of one fluid by another is a common process at petroleum industry, as completion and cementing operations of oil wells. The success of these fluids displacement guarantee the lifetime of the wells. The adequate operation occurs when the cement slurry distribution at the wall is homogeneous. In this work, experimental and numerical studies of Newtonian and non-Newtonian fluid displacement through annuli are performed. The experiments are performed using a scaled oil well model. The numerical solution of the governing conservation equations of mass and momentum is obtained using the finite volume technique and Fluent and OpenFOAM softwares. The multiphase modeling is performed using the volume of fluid (VOF) method. The effect of rheological parameters, density and viscosity ratios, geometry configuration, and flow rate on displacement efficiency was evaluated to optimize cementing operation. Tests were performed using model and real fluids, Newtonian and non-Newtonian. The displacement efficiency was evaluated analyzing the interface between fluids and measuring the density of the mixture at the annuli outlet through time.
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Chaffin, Stephen. "Non-Newtonian fluids in complex geometries". Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16750/.
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Alrashidi, Azizah. "Nonlinear control for non-Newtonian flows". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5777/.
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PDE-constrained optimization is an important area in the field of numerical analysis, with problems arising in a wide variety of applications including optimal design, optimal control and parameter estimation. The aim of such problems is to minimize a functional J(u,d) whilst adhering to constraints posed by a system of partial differential equations (PDE), with u and d used respectively to denote the state and control of the system. In this thesis, we describe the steady-state generalized Stokes equations for incompressible fluids. We proceed to derive the weak formulation of the problem, and show that the resulting system may be written in terms of a mixed formulation of the Stokes problem. Based on this formulation, the problem is discretized through use of the Galerkin finite element method, before investigating control problems based on the generalized Stokes equations, along with numerical experimentation. This work will be used to achieve the main aim of this thesis, namely the exploration and investigation of solution methods for optimal control problems constrained by non- Newtonian flow. Ultimately, an iterative solution method designed for such problems coupled with an appropriate preconditioning strategy will be described and analyzed, and used to produce effective numerical results.
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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.
17
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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Trinh, Khanh Tuoc. "Turbulent transport near the wall in newtonian and non-newtonian pipe flow". Thesis, University of Canterbury. Chemical Engineering, 1992. http://hdl.handle.net/10092/7693.
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Turbulence is present everywhere in our environment yet its complexities remain one of the great challenges in scientific and engineering research. This work began out of personal interest. As such, it involved all aspects of my background, not just my engineering training.
It is disconcerting to some westerners to think of scientists as philosophers. In the traditional Vietnamese culture, it is not possible to think of scientists as not being philosophers. In the old days we taught philosophy before we gave more practical training because all that we do IS influenced by our beliefs.
I was educated in French schools and New Zealand universities while being raised in a strongly nationalistic culture. This bicultural upbringing led at some stages of my youth to a painful crisis of identity but it greatly enriched my life and coloured my approach to science. The reader will find the influences of this background in my ideas about turbulence.
At one time, the West used to think of Asian beliefs as vague. I was first taught by an extraordinary Vietnamese electrical engineer that our description of the universe was in fact a binary progression. This is found in the Kinh Dich (in Chinese Yi-King, the Book of Change). This concept is not specific to the Vietnamese or Chinese cultures. It can be found in Indian thought, in Islamic Kybalion (their secret book), in Egyptian and South American cultures. Since that day, I have learned much more about traditional Vietnamese culture which is unconsciously reflected in some of the ideas I have developed in this research.
We believe that all phenomena are periodic. The manifestations that look continuous may in fact be thought of as an endless repetition of events that regenerate constantly. They are not static. I was not unduly surprised to learn of Fourier analysis which decomposes a continuous function into a series of periodic elements. I was thus receptive to the idea that one can define a timescale even for laminar flow, when I found it. It became eventually a transformation between the penetration and boundary layer theories of heat and mass transfer (Appendix A4).
We also believe, for example, that all things in Creation are governed by the same fundamental laws. In oriental medicine, it allowed us to understand and cure the human body by observing the laws that govern the larger universe. In essence, the organisation of the solar system is paralleled by that of the human body: there is a correspondence between the macrocosm and the microcosm. The reader will find a reflection of that thought in Chapter 9 where I endeavour to compare the information contained in time-averaged measurements to the those obtained from transient contributions.
We believe that, like us, the Earth breathes. In the teaching of Khi Cong (the equivalent of Yoga) which I studied briefly, it is important to take note of and keep in harmony with this natural cycle since we derive so many of our resources from the Earth where we live. I have often wondered whether our environmental engineering would not have benefited if those ideas had permeated into Western science.
To me, thoughts are not abstractions. They are concrete entities. We can now detect them through encephalograms. Thus thoughts that are conceived by a person are broad casted into the environment. If one is receptive, one can gather the wisdom of others around us. This is why Asian philosophy puts such an emphasis on emptying ourself of our own stray thoughts. This ultimate state of dispossession, mental as well as emotional and physical, is not easy to achieve because we tend to cling so hard to our own pre-conceived ideas. Vietnam can truly boast of having the most isolated scientific community in the world. The isolation imposed on the Vietnamese people by the Communists has forced many of us to face ourselves. In some cases it has been useful because this intellectual silence has made us much more receptive to the thoughts around us. In that sense, I have always felt that my work is simply the natural outcome of ideas evolved by my elders and colleagues in this field. In Phong Thuy (in Chinese Feng Shui, the art of shaping landscaping) the position where one buries one's ancestors is important because the configuration of the land filters the waves that are picked up by the remains of the deceased and transmitted to their descendants who are on the same wavelength. This is how innate talents are formed.
As a people, the Vietnamese have had a wonderful ability to assimilate and adapt the culture of the peoples we meet, even those who tried to conquer us. The tragic history of our country during the last hundred years has unfortunately eroded the confidence of many among us. The unfortunate policies of the Communist government during the last seventeen years have hit particularly hard and we risk losing much of our fine heritage. It is particularly painful for me to see how many of my friends, some certainly brighter than I am, have given up on research because the facilities, if they exist at all, are so much poorer than anywhere else. In the later years, the driving force behind the present work was no longer pure interest but the need to show that, whatever the circumstances, our achievements are only restricted by our perseverance with the task at hand. The work became a statement of philosophy as much as one of engineering research. My hope is that my work will make a contribution to the field, that it will be recognised as such and in a small way help the Vietnamese nation find itself again.
Trinh Khanh Tuoc
2 December 1992
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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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Jaber, Othman Jamal Othman. "Flow-Blurring and Air-Assisted Atomization of Newtonian and Non-Newtonian Liquids". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28167.
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A comprehensive study on Flow-Focusing/Flow-Blurring (FF/FB) atomizers is presented in this study. A transparent FF/FB atomizer is introduced in this work to aid in the characterization of sprays emitting from both of the atomizer’s regimes. Newtonian and non-Newtonian liquids were tested over a wide range of operating conditions and laser diagnostics were employed to unveil the resulting structures and salient features of the sprays.
Direct imaging of the atomizer’s liquid tube tip region enabled identification of the onset of the atomizer’s regime transition at different liquid tube recesses and over a wide range of conditions. New regime transition maps for FF/FB atomizers have been created that are function of ALR, Weber number, momentum flux ratio and liquid Re, and can be employed to identify the operating regime of atomizers and the controlling parameters for transition.
Spray droplet size and flow-field measurements using a PDPA/LDV setup were obtained and have enabled identification of unique flow features that characterize the FF and FB regimes, of importance is the shown dependence of the resulting droplet size on the operating Weber number for both regimes, and the trend of decreasing difference in droplet size between the two regimes as the Weber number increased.
The spray morphology of Newtonian and non-Newtonian liquids was also investigated. The FF regime was found to behave similarly to air-blast atomizers when operating with non-Newtonian liquids, it had an advantage though in the atomization of Newtonian liquids. The FB regime demonstrated the ability to always generate droplets immediately as the spray exited the atomizer when operating with Newtonian liquids. However, non-Newtonian liquids have proven to be difficult to atomize in the FB regime where the liquid separated into multiple streams and only broke up at far downstream locations.
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Amani, Ahmad. "Numerical simulation of Newtonian/non-Newtonian multiphase flows : deformation and collision of droplets". Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667419.
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The complex nature of multiphase flows, particularly in the presence of non-Newtonian rheologies in the phases, limits the applicability of theoretical analysis of physical equations as well as setting up laboratory experiments. As a result, Computational Fluid Dynamics (CFD) techniques are essential tools to study these problems. Despite the advances in numerical simulation techniques in this field in the past decade, the applicability of these approaches are limited by challenges appearing in specific applications, and particular consideration must be taken into account for each of these problems. The present thesis aims at three-dimensional numerical solution of Newtonian/non-Newtonian multiphase flow problems in the context of finite-volume discretization approach with applications in different natural and industrial processes.
This thesis is organized in five chapters. The first chapter aims at providing an introduction to the motivation behind this work. We also present some application of the context of this thesis in industrial processes, followed by a small introductory on the CTTC research group, objectives and the outline of the thesis. The core of this thesis lays within chapters two, three and four.
In chapter 2, using a conservative level-set method, three-dimensional direct numerical simulation of binary droplets collision is performed. A novel lamella stabilization approach is introduced to numerically resolve the thin lamella film appeared during a broad range of collision regimes. This approach demonstrates to be numerically efficient and accurate compared with experimental data, with a significant save-up on computational costs in three-dimensional cases. The numerical tools introduced are validated and verified against different experimental results for a wide range of collision regimes where very good agreement is seen. Besides, for all the cases studied in this chapter, a detailed study of the energy budgets are provided.
In chapter 3, the physics of a single droplet subjected to shear flow is studied in details, with a primary focus on the effect of viscosity on walls critical confinement ratio. First, we highly validate the ability of the numerical tools on capturing the correct physics of droplet deformation. This chapter continues by three-dimensional DNS study of subcritical (steady-state) and supercritical (breakup) deformations of the droplet for a wide range of walls confinement in different viscosity ratios. The results indicate the existence of two steady-state regions in a viscosity ratio-walls confinement ratio graph, which are separated by a breakup region. Overall, these achievements indicate a promising potential of the current approach for simulating droplet deformation and breakup, in applications of dispersion science and mixing processes.
In chapter 4, with the help of experience gained in the previous chapters, a finite-volume based conservative level-set method is used to numerically solve the non-Newtonian multiphase flow problems. One set of governing equations is written for the whole domain where different rheological properties may appear. Main challenging areas of numerical simulation of multiphase non-Newtonian fluids, including tracking of the interface, mass conservation of the phases, small timestep problems encountered by non-Newtonian fluids, numerical instabilities regarding the high Weissenberg Number Problem (HWNP), instabilities encouraged by low solvent to polymer viscosity ratio in viscoelastic fluids and instabilities encountered by surface tensions are discussed and proper numerical treatments are provided in the proposed method. The numerical method is validated for different types of non-Newtonian fluids, e.g. shear-thinning, shear-thickening and viscoelastic fluids using structured and unstructured meshes, where the extracted results are compared against analytical, numerical and experimental data available in the literature.La naturaleza compleja de los flujos multifásicos, particularmente en presencia de reologías no newtonianas, limita la aplicabilidad del análisis teórico de ecuaciones físicas y también de los experimentos de laboratorio. Por lo tanto, las técnicas de dinámica de fluidos computacional (CFD) son esenciales para estudiar estos problemas. A pesar de los avances en las técnicas de simulación numérica en esta área durante la última década, la aplicabilidad de estos enfoques está limitada por los desafíos que aparecen en las aplicaciones específicas, y se debe considerar de forma particular cada uno de estos problemas. La presente tesis tiene como objetivo la solución numérica tridimensional de los problemas de flujo multifase newtoniano / no newtoniano en el contexto del enfoque de discretización de volúmenes finitos con aplicaciones en diferentes procesos naturales e industriales. Esta tesis está organizada en cinco capítulos. El primer capítulo proporciona una introducción y la motivación de este trabajo. También presentamos alguna aplicación de esta tesis en procesos industriales, seguida de una corta introducción al grupo de investigación del CTTC, los objetivos y el resumen de la tesis. En el capítulo 2, utilizando un método CLS, se realiza una simulación numérica directa (DNS) tridimensional de colisión de gotitas binarias. Se introduce un nuevo enfoque de estabilización de lamella para resolver numéricamente la capa delgada de fluido ("lamella") que aparece durante muchos regímenes de colisión. Este enfoque demuestra ser numéricamente eficiente y preciso en comparación con los datos experimentales, con una importante reducción de costos computacionales en casos tridimensionales. Las herramientas numéricas introducidas se validan y verifican con diferentes resultados experimentales para diferentes casos de colisión en los que se observa un muy buen acuerdo. Además, para todos los casos estudiados en este capítulo, se proporciona un estudio detallado de los balances de energía. En el capítulo 3, se estudia en detalle la física de una sola gota sometida a flujo de cizallamiento, con un enfoque principal en el efecto de la viscosidad en el confinamiento crítico de las paredes. Primero, validamos la capacidad de las herramientas numéricas para capturar la física correcta de la deformación de las gotitas. Este capítulo continúa con el estudio tridimensional DNS de las deformaciones subcríticas (estado estable) y supercríticas (ruptura) de la gota para un amplio rango de confinamiento de paredes en diferentes relaciones de viscosidad. Los resultados indican la existencia de dos regiones de estado estable en un gráfico de una relación de confinamiento de las paredes y la viscosidad, que están separados por una región de ruptura. En general, estos logros indican un potencial importante del enfoque actual para simular la deformación y ruptura de las gotitas, en aplicaciones de la ciencia de la dispersión y los procesos de mezcla. En el capítulo 4, con la ayuda de la experiencia adquirida en los capítulos anteriores, se utiliza un método CLS de volumen finito para resolver numéricamente los problemas de flujo multifase no newtonianos. Las principales áreas desafiantes de la simulación numérica de fluidos multifásicos no newtonianos incluso el seguimiento de la interfaz, la conservación de masa de las fases, los problemas de pequeños paso de tiempo encontrados por los fluidos no newtonianos, las inestabilidades numéricas relacionadas con el problema del alto número de Weissenberg (HWNP), inestabilidades fomentadas por una baja relación de viscosidad de disolvente a polímero en fluidos viscoelásticos y las inestabilidades encontradas por las tensiones superficiales son discutidos y se proporcionan tratamientos numéricos adecuados para el método propuesto. El método numérico se valida para diferentes tipos de fluidos no newtonianos, utilizando diluyentes de cizallamiento, espesamiento de cizallamiento y fluidos viscoelásticos utilizando mallas estructuradas y no estructuradas, donde los resultados extraídos se comparan con los datos analíticos, numéricos y experimentales disponibles en la literatura.
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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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Anderson, Brian. "Development of a non-Newtonian latching device". Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3855.
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Callahan, Thomas Patrick. "Non-Newtonian fluid injection into granular media". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39618.
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The process of fluid injection into granular media is relevant to a wide number of applications such as enhanced oil recovery, grouting, and the construction of permeable reactive barriers. The response of the subsurface is dependent on multiple factors such as in-situ stresses, fluid properties, flow rate, and formation type. Based on these conditions a variety of response mechanisms can be initiated ranging from simple porous infiltration to hydraulic fracturing.
Currently, the mechanics of fluid injection into competent rock are well understood and can be sufficiently modeled using linear elastic fracture mechanics. Because the grains in rock formations are individually cemented together, they exhibit cohesion and are able to support tensile stresses. The linear elastic method assumes tensile failure due to stress concentrations at the fracture tip. A fracture propagates when the stress intensity factor exceeds the material toughness (Detournay, 1988)
However, understanding fluid injection in cohesionless granular media presents a much larger obstacle. Currently, no theoretical models have been developed to deal with granular media displacements due to fluid injection. Difficulty arises from the complexity of fluid rheology and composition used in engineering processes, the strong coupling between fluid flow and mechanical deformation, the non-linear response of subsurface media, and the multi-scale nature of the problem.
The structure of this thesis is intended to first give the reader a basic background of some of the fundamental concepts for non-Newtonian fluid flow in granular media. Fluid properties as well as some interaction mechanisms are described in relation to the injection process. Next, the results from an experimental series of injection tests are presented with a discussion of the failure/flow processes taking place.
We developed a novel technique which allows us to visualize the injection process by use of a transparent Hele-Shaw cell. Specifically, we will be using polyacrylamide solutions at a variety of concentrations to study non-Newtonian effects on the response within the Hele-Shaw cell. By performing tests at a range of solution concentrations and injection rates we are to be able to identify a transition from an infiltration dominated flow regime to a fracturing dominated regime.
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Lopez, Xavier. "Pore-scale modelling of non-Newtonian flow". Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415320.
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Ismail, Baharum. "Crossflow microfiltration of concentrated non-Newtonian slurries". Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/11787.
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Crossflow filtration of non-Newtonian slurries of magnesia and talc suspensions on micron-size membranes has been investigated. Three major membranes PTFE capillary, metal and ceramic tubes were employed and challenged by concentrated slurries more than 25 % by weight. Crossflow velocity, system pressure and slurry concentration are considered in relation to the possible deposit thickness and permeate flux behaviour. A thorough investigation of pressure drop in tubes of similar dimensions to the membranes has also been carried out in order to identify and develop an appropriate model. The experimental results, especially the deposit depth and flux rate are compared with the model prediction which is based on a permeate flux rate with shear stress correlation. Furthermore, diafiltration experiments were carried out and washing efficiency is compared with a stirred tank model of the process. Measurement of pressure drop in tubes confirmed the mathematical model used to determine the diameter open to flow during filtration, i.e. the deposit thickness. Overall crossflow experimental results show reasonable agreement with the predictions of the proposed models. The pseudo steady state flux is shown to correlate with the wall shear stress and the correlation is much improved when the deposit depth on the membrane was taken into account. In most cases the deposit depth and permeate flux rate are correctly predicted once the basic parameters correlation data and slurry rheology were determined. Since the rheology properties can be determined independently, the mathematical model developed is very practical and could be extended to some other systems, for example tube diameter. Hopefully, the translation of these parameters could be used to design and then develop the appropriate equipment when crossflow filtration of concentrated slurries is concerned, and in the design of systems to prevent tube blockage.
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Smith, Sarah Elizabeth. "Turbulent duct flow of non-Newtonian liquids". Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399184.
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The turbulent flow of non-Newtonian fluids in straight ducts has been investigated. Specifically, the fully developed circular pipe flow, axisymmetric sudden expansion flow and fully developed square duct flow were studied. The pipe flow study analysed previous measurements of the mean velocity profiles and friction factor-Reynolds number characteristics of different non-Newtonian fluids in pipe fully developed pipe flows. An investigation of different nondimensional parameters permitted initial progress on developing a correlation between drag reduction and fluid rheology to be made. Comparison of the ranking orders of drag reduction, fluid extensional viscosity and fluid elasticity revealed that these fluid properties are most strongly correlated with drag reduction at low shear/strain rates (that is, in the buffer and outer regions of the boundary layer). The sudden expansion geometry was investigated for flows of aqueous Xanthan gum solution and two reference Newtonian fluids. A smooth contraction was placed at the inlet to the sudden expansion. Few significant differences were observed between the mean flow behaviours of the test fluids for the turbulent Reynolds numbers tested (26,000 and 80,000). These results may reflect the manner in which the rigid, rod-like molecules found in Xanthan gum influence the flow behaviour. Turbulence measurements indicated that all three turbulence components were suppressed for the polymer solution flow within the free shear layer downstream of the expansion. The turbulent flow of two non-Newtonian fluids (a blend ofXanthan gum and Carboxymethylcellulose in water and an aqueous solution of polyacrylamide) in a square duct were compared with a turbulent Newtonian square duct flow. Although suppression of the transverse turbulence components was noted, the polymer solutions also strongly affected the behaviour of the secondary flows found in turbulent non-circular duct flows of Newtonian fluids. Specifically, the secondary flows appeared to be weakened in the polymer blend flow and completely suppressed in the polyacrylamide solution flow. It is anticipated that fluid elasticity is influential in this suppression
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Wang, Yuli. "Capillarity and wetting of non-Newtonian droplets". Doctoral thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184146.
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Capillarity and dynamic wetting of non-Newtonian fluids are important in many natural and industrial processes, examples cover from a daily phenomenon as splashing of a cup of yogurt to advanced technologies such as additive manufacturing. The applicable non-Newtonian fluids are usually viscoelastic compounds of polymers and solvents. Previous experiments observed diverse interesting behaviors of a polymeric droplet on a wetted substrate or in a microfluidic device. However, our understanding of how viscoelasticity affects droplet dynamics remains very limited. This work intends to shed light on viscoelastic effect on two small scale processes, i.e., the motion of a wetting contact line and droplet splitting at a bifurcation tip. Numerical simulation is employed to reveal detailed information such as elastic stresses and interfacial flow field. A numerical model is built, combining the phase field method, computational rheology techniques and computational fluid dynamics. The system is capable for calculation of realistic circumstances such as a droplet made of aqueous solution of polymers with moderate relaxation time, impacting a partially wetting surface in ambient air. The work is divided into three flow cases. For the flow case of bifurcation tube, the evolution of the interface and droplet dynamics are compared between viscoelastic fluids and Newtonian fluids. The splitting or non-splitting behavior influenced by elastic stresses is analyzed. For the flow case of dynamic wetting, the flow field and rheological details such as effective viscosity and normal stress difference near a moving contact line are presented. The effects of shear-thinning and elasticity on droplet spreading and receding are analyzed, under inertial and inertialess circumstances. In the last part, droplet impact of both Newtonian and viscoelastic fluids are demonstrated. For Newtonian droplets, a phase diagram is drawn to visualize different impact regions for spreading, splashing and gas entrapment. For viscoelastic droplets, the viscoelastic effects on droplet deformation, spreading radius and contact line motion are revealed and discussed.QC 20160329
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Agarwal, Akshat. "Breakdown to turbulence in non-Newtonian flow". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/43851.
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Transition to turbulence in polymeric channel flow is investigated, with the FENE-P model used to characterize the viscoelastic behaviour of the flow. Simulations are performed to study transition through both the natural and bypass routes. In the linear growth regime of natural transition, differences in the growth rate of a TS wave are explained by appealing to the production of the perturbation energy budget. At high Weissenberg number, the growth rate is substantially lower in comparison to Newtonian flow. As a result, the transition process is prolonged. Upon the introduction of three dimensional disturbances, Newtonian and non-Newtonian cases undergo transition through the H-type instability. The spanwise extent of the lambda structures during transition is larger in non-Newtonian flow. Bypass transition is initiated by an initially-localized disturbance. In the linear growth regime, the flow response is stabilized by viscoelasticity, and the maximum attainable disturbance-energy amplification is reduced with increasing polymer concentration. The reduction in the energy growth rate is attributed to the polymer work, which plays a dual role: First, a spanwise polymer-work term develops, and is explained by the tilting action of the wall-normal vorticity on the mean streamwise conformation tensor. This resistive term weakens the spanwise velocity perturbation thus reducing the energy of the localized disturbance. The second action of the polymer is analogous, with a wall-normal polymer work term that weakens the vertical velocity perturbation. Its indirect effect on energy growth is substantial since it reduces the production of Reynolds shear stress and in turn of the streamwise velocity perturbation, or streaks. During the early stages of non-linear growth, the dominant effect of the polymer is to suppress the large scale streaky structures which are strongly amplified in Newtonian flows. As a result, the process of transition to turbulence is prolonged and, after transition, a drag reduced turbulent state is attained.
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Little, Stephen Nicholas. "The flow behaviour of non-Newtonian sludges". Thesis, University of Greenwich, 1998. http://gala.gre.ac.uk/6228/.
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A large body of data is analysed of the flow of concentrated sewage sludge through straight pipes. Mathematical models are obtained of the laminar and turbulent flow of each main category of sewage sludge. The sludges are modelled as time-independent, non-Newtonian relations between shear stress, rate of shearing strain, and solids concentration. Due to the inhomogeneity of sewage sludge, error analysis becomes pivotal to the data analysis, and options are examined for reducing the error of each model with one or more user-fitted parameters. Parameter estimation is discussed for viscous, time-independent, non-Newtonian, laminar and turbulent flow models. Due to extensive requirements of the data analysis, the parameter estimation methods are robust, and generally suitable for any shear flow relation. The difficulties of estimating parameters of shear flow models from pipe flow data are addressed. Numerical algorithms are presented for modelling the flow of time-independent, non-Newtonian, viscous fluids through a straight pipe. Laminar, critical and turbulent flow algorithms are developed to offer predictions such as pressure gradient, mean cross-sectional velocity, and the velocity distribution. To handle the requirements of the data analysis, the algorithms impose few restrictions on the type of shear flow relation, the flow velocity, and the pipe diameter. Suitable pipe flow equations are chosen, and are manipulated mathematically into forms that would yield robust and efficient schemes. The appropriate use of numerical methods for the algorithms is investigated. Mathematical models of sludge are for use by the sewage industry to give an idea of the flow behaviour of sludges for any relevant application. The parameter estimation techniques and pipe flow algorithms are not constrained to any particular pipe, fluid or flow conditions, so they would be useful for any relevant application.
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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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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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Dressler, Daniel. "An experimental investigation of Newtonian and non-Newtonian spray interaction with a moving surface". Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/71.
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As a logical extension of previous work conducted into viscoelastic atomization, initially motivated by the need to improve spray coating transfer efficiencies, an experimental investigation into the spray-surface interaction for a number of Newtonian and non-Newtonian substitute test liquids is presented. Three model elastic liquids of varying polymer molecular weight and three inelastic liquids of varying shear viscosity were sprayed upon a moving surface to isolate the effect of elasticity and shear viscosity, respectively, on spray impaction behavior. In addition, two liquids exhibiting shear thinning behavior and an industrial top of rail liquid friction modifier, KELTRACK, for use in the railroad industry, were included in the spray tests. High-speed photography was used to examine the impingement of these liquids on the surface.
Ligaments, formed as a consequence of a liquid’s viscoelasticity, were observed impacting the surface for 300K PEO, 1000K PEO, and KELTRACK. These ligaments were broadly classified into four groups, based on their structure. Splashing of elastic liquid ligaments and droplets led to filamentary structures being expelled from the droplet periphery, which were then carried away by the atomizing air jet, leading to reductions in transfer efficiency. The effect of increasing elasticity amongst the three varying molecular weight elastic solutions was shown to increase the splash threshold; a similar effect was noted with increasing shear viscosity.
Attempts were made at quantifying a critical splash-deposition limit for all test liquids however due to imaging system limitations, no quantitative conclusions could be made.
For KELTRACK, both droplets and ligaments spread and deposited on the rail surface upon impact, with no observed splash or rebound. Splash was only noted when droplets impinged directly on a previously deposited liquid film and even then, splashing was well contained. Thus, KELTRACK’s current rheological formulation proved to be very effective in ensuring high coating transfer efficiencies.
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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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Vayssière, Brandão Pedro <1993>. "Linear and nonlinear thermal instability of Newtonian and non-Newtonian fluid saturated porous media". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10143/1/VayssiereBrandao_Pedro_PhD_Thesis.pdf.
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The present work aims to investigate the influence of different aspects, such as non-standard steady solutions, complex fluid rheologies and non-standard porous-channel geometries, on the stability of a Darcy-Bénard system. In order to do so, both linear and nonlinear stability theories are considered. A linear analysis focuses on studying the dynamics of the single disturbance wave present in the system, while its nonlinear counterpart takes into consideration the interactions among the single modes. The scope of the stability analysis is to obtain information regarding the transition from an equilibrium solution to another one, and also information regarding the transition nature and the emergent solution after the transition. The disturbance governing equations are solved analytically, whenever possible, and numerical by considering different approaches. Among other important results, it is found that a cylinder cross-section does not affect the thermal instability threshold, but just the linear pattern selection for dilatant and pseudoplastic fluid saturated porous media. A new rheological model is proposed as a solution for singular issues involving the power-law model. Also, a generalised class of one parameter basic solutions is proposed as an alternative description of the isoflux Darcy--Bénard problem. Its stability is investigated.
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Rostami, Behnam <1986>. "Experimental Analysis of Droplet Generation in Presence of Newtonian and non-Newtonian Flows within Microjunctions". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8600/1/Thesis_final_Behnam%20Rostami.pdf.
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Microdroplets have attracted increasing interest among researchers due to the wide spread of promising technological applications such as biological analysis, cancer diagnosis, drug discovery and chemical reactions. With respect to traditional emulsion methods which are usually able to produce droplets with a broad size variation (polydispersed emulsions), microfluidic devices have been developed to produce monodispersed microdroplets with a controllable size. The diameter and size variation of droplets are controlled by a series of parameters, including the geometries and dimensions of the microfluidic devices, properties of the liquids, flow rates and surfactant concentrations.
In this Ph.D. thesis, droplet formation has been analyzed experimentally, thanks to a series of specific tests on simple microfluidic devices devoted to droplet generation based on the use of T-junctions or micro cross-junctions. The experimental work has been focused on the analysis of the control of droplet regime which can be activated in a microfluidic droplet generator in presence of Newtonian and non-Newtonian dispersed phases, with or without the addition of surfactants. The mechanism of the droplet formation has been studied by following the evolution of the interface between the immiscible liquids at the microjunction thanks to the post processing of images acquired by using a speed camera connected to an inverted microscope. In order to study the behavior of non-Newtonian shear thinning liquids during droplet formation, Xanthan gum aqueous solutions have been used because their rheological properties are very similar to those of blood. The effect on the droplet regimes of the main controlling parameters, such as the flow rates of the immiscible liquids introduced in the microfluidic device, fluid viscosity and interfacial tension has been studied with the aim to individuate the range of these controlling parameters for which the microfluidic device is able to produce monodispersed droplets with an assigned volume and frequency.
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Mouzouri, Miloud. "Non-Newtonian Flow Modelling Through A Venturi Flume". Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0091.
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Lors d’une opération de forage, un certain nombre d’événements imprévus par rapport à l’écoulement du fluide de forage dans le puits, peuvent se produire assez rapidement. Des exemples de tels événements sont les afflux de pétrole ("kick") ainsi que les pertes de boue dans la formation. Un "kick" qui augmente en intensité peut entraîner, par ce que l’on nomme, un "blowout" (par exemple l’incident Deepwater Horizon en 2010). Les pertes et les gains sont habituellement détectés en contrôlant l’équilibre de la boue de forage dans le puits, en particulier en contrôlant le débit sortant du puits et en le comparant au débit entrant induit par les pompes. La plupart des méthodes de surveillance, de l’écoulement du puits en cours de forage, est d’utiliser un simple "paddle" (capteur qui mesure la hauteur du fluide de forage avec l’inclinaison d’une pagaie) dans la ligne d’écoulement de retour, ou d’utiliser un débitmètre de Coriolis (débitmètre connu pour sa précision, mais coûteux et nécessite une installation complexe en ajoutant un "by-pass"). Il y a un besoin évident d’un nouveau débitmètre précis, mais facile à installer et peu coûteux. Le canal Venturi a été utilisé comme débitmètre pendant des années dans l’industrie des eaux. Il apparaît comme une solution peu chère mais précise pour mesurer des débits importants. Beaucoup de personnes ont travaillé sur cette solution pour améliorer sa précision et élargir son champ d’application. Ils ont développé des modèles, sur la base d’un processus d’étalonnage, permettant de relier la hauteur en amont au débit. Cela signifie que les modèles actuels, comme ISO NORM 4359 [1], peuvent être uniquement utilisés pour l’écoulement d’eau et pour une géométrie bien spécifique. Comme nous le savons, les boues ont des comportement non- Newtonien, et donc ces modèles établis ne peuvent pas être utilisés avec ce type de fluides. Pour notre application, la forme trapézoïdale apparaît comme un bon compromis entre la précision et la portée des mesures de débit. Ainsi, nous avons développé un modèle capable de calculer le débit en prenant en compte les propriétés du fluide ainsi que les paramètres géométriques du canal. Ce modèle a été simplifié sous forme 1D en utilisant la théorie des eaux peux profondes, et a été complété par un modèle de friction tenant en compte de la variation des propriétés des fluides et de la géométrie du canal. Ce modèle a été validé par une série d’expériences avec les deux types de fluides: Newtonien et non-Newtonien, où nous avons mesuré le débit et la hauteur de l’écoulement à différents endroits le long du canal Venturi. Nous avons également réalisé des simulations 3D, en simulant des écoulements Newtoniens et non- Newtonien le long du canal. Pour généraliser cette étude, cette démarche a été étendue à une autre forme de Venturi plus adapté à un certain design de plate-forme pétrolière. Les corrélations et les modèles développés et validés expérimentalement au cours de cette étude peuvent être utilisés pour étendre l’utilisation des canaux Venturi à tous les fluides Newtonien mais aussi non-Newtonien. Il est maintenant l’occasion pour les industries de proposer une solution, peu chère mais précise pour mesurer les débits dans des canaux ouverts et pour tous types de fluidesDuring a drilling operation, a certain number of unexpected events, related to the flow of drilling fluid in the well, may happen rather quickly. Examples of such events are formation fluid influx (kick) and mud loss to the formation. An uncontrolled kick that increases in intensity may result in what is known as a blowout (e.g. the Deepwater Horizon incident in 2010). Influxes and kicks are traditionally detected by monitoring the drilling mud balance in the well, in particular, by monitoring the flow out the well and comparing it to the incoming flow induced by the pumps. Most methods of monitoring the flow out of the well while drilling consists in using a simple paddle (sensor that measures the height of drilling fluid with the inclination of a paddle) in the return flow line, or in using a Coriolis flow meter (flow meter known for its accuracy but expensive and requires a complex installation by adding a bypass). There is a clear need of a new accurate flow meter, but easy to install and inexpensive. The Venturi flume has been used as flow meter for years in water industry. It appears as a cheap but accurate solution to measure large flow rates. Many people have worked on this solution to improve its accuracy and to expand its scope. They have developed models, based on a calibration process, to relate the upstream height to the flow rate. This means that current models, as ISO NORM 4359 [1], can be used only for water flow and specific geometry. As known, muds have non-Newtonian behavior and water models cannot be used with this kind of fluids. For our application, trapezoidal shape appears as a good compromise between accuracy and range of flow rate measurements. Thus, we built a model able to compute the flow rate with taking into account fluid properties and geometrical parameters. This model is simplified in 1D form by using the Shallow Water theory, and completed by a friction model taking into account the variation of fluid properties and geometry along the open channel. It have been validated by series of experiments with both Newtonian and non-Newtonian fluids, where we measured the flow rate and heights of the flow at different locations along the trapezoidal Venturi flume. It have been also completed by 3D CFD which has been simulated both Newtonian and non-Newtonian flows along the flume. To generalized this study, the work was extended to another shape of Venturi more suited to some rig design. The correlations and models developed and experimentally validated during this research can be used to extend the use of Venturi flume flow meters for any fluids : Newtonian and non- Newtonian. It is an opportunity for industries to propose a cheap but accurate solution to measure flow rates in open channels with any kind of fluids
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Wielage, Kerstin. "Analysis of non-Newtonian and two-Phase flows". kostenfrei, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978191463.
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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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Vongvuthipornchai, Somporn. "Well test analysis for non-Newtonian fluid flow /". Access abstract and link to full text, 1985. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8603796.
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Ketheeswaranathan, Nishanthi. "Rehological study of non-Newtonian fluid through microchannels". Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540775.
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Ngamaramvaranggul, V. D. "Numerical simulation of non-Newtonian free surface flows". Thesis, Swansea University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638326.
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Finite element numerical simulations are presented for two-dimensional creeping, planar and axisymmetric incompressible isothermal complex flows of both Newtonian and viscoelastic fluids. A number of constitutive equations are used to define fluid properties, including Newtonian, Oldroyd-B and Phan-Thien/Tanner (PTT) models. For viscoelastic flow, a modified semi-implicit Taylor-Galerkin method is presented with a consistent streamline upwind Petrov-Galerkin technique for the stress terms. Velocity gradient recovery is also employed. This multi-stage numerical solution algorithm implements a time marching, pressure-correction procedure. The significant influence of die-swell on the free surface flow development for wire-coating flows is reported and discussed in the results. The simulation of Poiseuille and annular flow of Newtonian and Oldroyd-B fluid for stick-slip and die-swell problems is presented. A planar- Newtonian stick-slip flow is compared with the analytical solution, whilst an axisymmetric die-swell case is compared against the theory and other numerical methods. Analysis for two free surface formulations is performed and results are shown for varying structure and mesh refinement. Investigation into the influence of elasticity and drag flow components on free surface location is performed for an Oldroyd-B fluid. The results indicate that, as elasticity increases, pressure and stresses do likewise. The swelling ratio, expressed in terms of extrudate swell, depends especially on this elastic influence. Newtonian fluid with slip effects and a viscoelastic analysis of PTT models are described for a low density, high speed wire-coating process on pressure-tooling and tube-tooling dies. Fluid coating flows such as these are especially useful in industrial wire coating processes for covering surface areas with one or more thin uniform layers of polymer melt. Pressure-tooling dies are used for coating narrow-gauge wires, whilst tube-tooling dies deal with wide-bore cables. The impact of variation in slip models at the die walls, and the effects of drag pressure driven flow are explored. Slip influence reduces swelling-ratio, but increases oscillations in the pre-die exit region. Comparison of pressure-tooling between PTT models are shown with variation in shear-thinning and stain-softening properties. The effects of deviation in polymeric viscosity and Weissenberg number are presented. The results have been confirmed through mesh refinement.
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DUTRA, EDUARDO STEIN SOARES. "DISPLACEMENT OF NON-NEWTONIAN LIQUIDS IN ECCENTRIC ANNULI". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6947@1.
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PETRÓLEO BRASILEIRO S. A.Após a perfuração de poços de petróleo, a lama utilizada na remoção de cascalho, lubrificação e resfriamento da broca deve ser removida e substituída por uma mistura de cimento. Essa substituição se dá pelo deslocamento de um fluido por outro no espaço anular entre a formação rochosa e a coluna de completação ou revestimento. A mistura de cimento tem a função de garantir a estabilidade estrutural do poço evitando danos ambientais e prejuízos econômicos. Para melhores resultados do processo de cimentação, utilizam-se fluidos intermediários, também chamados de colchões lavadores e espaçadores, entre os fluidos principais. A boa qualidade do deslocamento dos fluidos pode ser avaliada pela forma da interface entre eles. Perfis mais acentuados sugerem um atravessamento indesejável do fluido deslocante (cimento) através do deslocado (fluido de perfuração). Por outro lado, perfis achatados indicam um deslocamento mais eficiente. Neste trabalho foi feita uma análise experimental e numérica do processo de cimentação, investigando a forma da interface e a eficiência do deslocamento dos fluidos. Uma planta experimental vertical foi construída, simulando um processo de deslocamento de fluidos em anulares excêntricos de poços. Com uma câmera digital CCD foram filmadas as interfaces entre os fluidos durante o escoamento e com essas imagens puderam-se comparar os resultados com as simulações numéricas realizadas num softw are comercial, usando o método de volumes finitos. Foram analisados os efeitos de diferentes parâmetros como a excentricidade, o regime de escoamento, e, principalmente o comportamento mecânico dos fluidos envolvidos (reologia) na eficiência do deslocamento. Com base nesses resultados é possível prever quais parâmetros operacionais otimizam o processo de deslocamento.
In cementing processes of oil wells, the mud formerly used to drag the gravel, to lubricate and to cool the drill is removed and substituted by a cement mixture. This substitution is obtained by the displacement of a fluid by another in the annulus between the rock formation and the casing. For best results of cementing process, intermediate fluids, also called spacers, are used between the drill mud and the cement mixture. The displacement process is very complex due to geometry and fluids characteristics. The annular space is eccentric in most cases, and both drilling mud and cement mixtures are non-Newtonian fluids. In this work, an experimental and numerical study is performed to analyze this process. A vertical experimental plant was constructed to simulate the fluid displacement through eccentric annuli. The interface shapes between two adjacent fluids were visualized using a digital CCD camera. The images were compared with the results obtained in the numerical simulations. The numerical solution was obtained via the Finite Volume technique and using the Volume-of-Fluid method. The effects of eccentricity, displacement velocity and rheological parameters on the displacement e± ciency were investigated. Based on these results we can predict the liquid characteristics and the operational parameters that optimize the displacement process.
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BAZZI, MARISA SCHMIDT. "BREAKUP DYNAMICS OF NON-NEWTONIAN THIN LIQUID SHEETS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34574@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
PROGRAMA DE EXCELENCIA ACADEMICA
BOLSA NOTA 10
Filmes finos de líquidos estão presentes em uma gama de aplicações industriais, como processos de atomização e revestimento de substrato. O processo de quebra pode ser divido em duas etapas: o estágio de ruptura, e o estágio de retração. O primeiro, movido pelas forças de van der Waals, ocorre quando uma pequena perturbação cresce e provoca o aparecimento de um pequeno furo no filme. O segundo, movido por forças capilares, provoca o crescimento desse furo levando à desintegração do filme de líquido. A estabilidade de uma cortina de líquido depende das características da perturbação, da espessura do filme e das propriedades do fluido. Análises experimentais mostraram que uma cortina super fina pode ser obtida pela utilização de fluidos viscoelásticos. Os mecanismos físicos associados à esta estabilidade, contudo, não são totalmente compreendidos. Este trabalho apresenta um estudo numérico e teórico dos efeitos das propriedades viscoelásticas na estabilidade de uma cortina de fluido, englobando ambos os estágio do processo. As análises numéricas foram desenvolvidas através da expansão assintótica das variáveis do escoamento com aplicação de um esquema de integração no tempo totalmente implícito. A partir da análise teórica da dinâmica de ruptura foi possível obter um critério de estabilidade linear para perturbações planares e axissimétricas em fluidos Newtonianos e não-Newtonianos. O tempo de ruptura e a velocidade de retração do filme foram calculados numericamente como função das propriedades viscoelásticas do líquido. Resultados mostraram que as forças elásticas atuam de forma a dificultar o processo de quebra e retração. Análises da evolução da espessura mostraram que as propriedades reológicas do fluído também interferem no formato que o filme de fluido assume durante o processo de retração. Para regimes de baixa viscosidade, as forças elásticas atuaram evitando a formação de ondas capilares observadas em fluidos Newtonianos.
Thin free liquid sheets are ubiquitous in many industrial processes, such as atomization and curtain coating. Liquid sheets are susceptible to instabilities at the interface, which can grow, triggering a breakup process. This process can be divided into two different stages: the rupture stage and retraction. The first, driven by van der Waals force, occurs when a small instability grows until it pinches-off the sheet. The second, driven by capillary forces, induces the growth of the hole caused by the pinch-off, leading to the full disintegration of the liquid sheet. The stability of a liquid sheet depends on disturbance characteristics, sheet thickness, and fluid properties. Experimental analyses have shown that thinner stable liquid curtain can be obtained with viscoelastic liquids. The underlyning physical mechanisms associated with increased stability are, however, not fully understood. This work presents a theoretical and numerical analysis of the effect of viscoelasticity on the stability of a thin liquid sheet during both stages of the breakup process. We first analyze the rupture dynamics, deriving linear stability criteria for both planar and axisymmetric perturbations of Newtonian and Oldroyd-B liquids. The time evolution of planar and axisymmetric perturbations in an Oldroyd-B liquid sheet is evaluated using the asymptotic expansion of the flow variables and a fully-implicit time integration scheme. The rupture time and retraction velocity are calculated as a function of the viscoelastic properties. The results show that the liquid rheological behavior does not influence the linear stability criterion. Nevertheless, it has a strong effect on the growth rate of the disturbance and retraction velocity, increasing, thus, the breakup time. The results show that elastic forces act to hinder the rupture and retraction stages. Analysis of the temporal evolution of the thickness profile reveals that liquid rheological behavior also affects the shape of the liquid sheet. For low viscosity regime, the elastic forces damp the capillary waves that arise during the retraction of Newtonian sheets.
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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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Kabwe, Aime Mume. "Non-Newtonian loss coefficients for Saunders diaphragm valves". Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/914.
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Dissertation submitted in fulfilment of requirements for the degree
Master Technology: Chemical Engineering
in the FACULTY OF ENGINEERING
at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2009The prediction of the energy losses when designing pipeline and pumping systems requires accurate loss coefficient data. But the loss coefficient data found in the open literature was not adequate for predicting the loss coefficient for Saunders straight-through diaphragm valves. As more accurate loss coefficient data to enable more efficient pipeline designs are scarce in the open literature, it is problematic to predict the head loss due to the pipeline fittings, and particularly for diaphragm valves. Most of the data given in the literature are for turbulent flow based on water. Due to water shortages mining operations are forced to increase their solids concentrations and to operate in laminar flow (Slatter, 2002). Consequently there is a need to determine loss coefficient data in laminar flow for valves used in these industries to ensure energy efficient designs (Pienaar et al., 2001; 2004) or if needed, to derive a new correlation to predict losses through Saunders diaphragm valves. However, a systematic study of various sizes of diaphragm valves of different manufacturers to ascertain, if the same loss coefficient can be applied, has never been done. Therefore a comparison will be made between the data produced in this work and the existing correlations. The objective of this research was to determine loss coefficient data in laminar, transitional and turbulent flow for the Saunders type straight-through diaphragm valves ranging from 40 mm to 100 mm in the fully open, 75 %, 50 % and 25 % open positions, using a range of Newtonian and non-Newtonian fluids. The test work was conducted on the valve test rig in the Flow Process Research Centre at the Cape Peninsula University of Technology. This work investigated only Newtonian and time independent homogeneous non-Newtonian fluids or slurries flowing through Saunders straight-through diaphragm valves in the turbulent, transitional and laminar regimes. Weir-type Saunders valves and time-dependent fluid behaviour were not investigated in this study. Preamble Non-Newtonian Loss Coefficients for Saunders Diaphragm Valves A Mume Kabwe The results for each test are presented in the form of valve loss coefficient (kvalve) against Reynolds number (Re). This thesis adds new loss coefficient data to the open literature, and a new correlation, which will be useful for designing pipelines in industries, as well as contributing to the academic debate in this discipline.
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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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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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