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1
Hegseth, John. "Spatiotemporal patterns in flow between two independently rotating cylinders /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487676847116532.
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Seto, Mae L. "Flow interference effects between two circular cylinders of different diameters." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29762.
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This thesis investigates different examples of action at a distance, namely the interaction
of two circular cylinders of different diameters and the interaction of a cylinder with a wall in various arrangements. Action at a distance modifies both the lift and drag of each one of the objects. The fluid flow interaction between a circular cylinder (of diameter D) with a wall, and a circular cylinder with a smaller (¼D) circular cylinder at Reynolds numbers of ≈ 10,000 were of interest. Manifestations
of the interactions include mutual changes in the lift and drag forces, phase, onset and frequency of vortex shedding on the circular cylinders/wall. A novel force measurement device for lift and drag of circular cylinders and a data acqusition system was built to realize the above experiments in a water towing tank. The system was capable of simultaneously measuring lift and drag on two circular cylinders with time resolution and correlating these measurements with flow field pictures. Measurements of the lift and drag and phase, onset and frequency of vortex shedding were taken on the large and small cylinder simultaneously as a function of the relative position between itself and the smaller cylinder as the two are towed. These measurements make it possible to map out the areas within the cylinders' sphere of influence and measure the intensity of this influence as a function
of the distance between the two cylinders. Every quantity that was mutually altered by the presence of another cylinder is used as measurements of the area of influence for a circular cylinder. It was found in general that the forces act up to a distance of about 3 diameters in the lateral direction. It was also noted that pressure fluctuations at the vortex shedding frequency penetrate into the laminar flow region up to about 3D in the lateral direction. The results agree with existing
results for wall/cylinder proximity experiments and flow interference between identical
circular cylinders. A novel method to trigger the onset of vortex shedding for towing tanks was also discovered.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate
3
Jasmine, Hosne Ara. "Hydromagnetic stability of a flow between two co-axial cylinders." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0024/MQ51368.pdf.
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Zakaria, Khaled Yahia. "Flow interaction and heat transfer between two cylinders in a uniform air stream." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960643664.
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Ali, M. A. "Thermal and MHD effects on the stability of Couette flow between two rotating cylinders." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383882.
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Hird, Lee D. "Analysis of the flow field between two eccentric rotating cylinders in the presence of a slotted sleeve." Curtin University of Technology, School of Mathematics and Statistics, 1997. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=11104.
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Overend et al [68] designed a viscometer to measure the viscosity of slurries that have a tendency to settle. This viscometer consists of a rotating ribbed rotor surrounded by a stationary slotted sleeve; this system is then placed eccentrically within an inclined rotating bowl. It, is claimed that this overcomes most of the difficulties encountered when attempting to obtain accurate measurements for these types of mixtures. If the mixture being sheared within the annulus does not represent the true composition of the slurry being, tested then the results are expected to be inaccurate. The presence of sediment at the bottom of the rotor or the formation of large masses of particles within the flow domain will affect the accuracy of the measurements obtained. This dissertation studies the amount of flow through the slotted sleeve and the region, or regions, of low shear rate within the flow domain. Assuming that end-effects are unimportant and that the slurries can be replaced by a single-phase fluid, three two-dimensional models are proposed. These models are designed to capture the large-slot construction of the sleeve and the, approximate, non-Newtonian behaviour of the slurries. The first two models solve analytically (using a regular perturbation scheme) and numerically (using a finite volume method) the moderate-and large-Reynolds-number flow, and the third model uses a finite volume method to study the flow patterns developed by pseudoplastic fluids. The results show that the mixing of the slurry is expected to be enhanced by moving the concentric system (i.e., the rotor and the slotted sleeve) close to the rotating bowl and using low to moderate speeds for the rotor and bowl. In addition, when the cylinders rotate in the same directions, two (counter-rotating) eddies are present within the flow domain; whereas, only one eddy (rotating counter-clockwise) is ++<br>present when the cylinders rotate in opposite directions. The presence of eddies in the former situation inhibits the flow through the sleeve; while, for moderate rotorspeeds, the flow through the sleeve is enhanced in the latter. When the slurry assumed pseudoplastic, we observe a region of low shear rate located near the dividing streamline present within the flow field. The distribution of shear rate within the flow field is shown to be affected by factors such as the rate of diffusion of the apparent viscosity and the value of the power law index. Therefore, this study suggests that for certain types of slurries, concentrations of particles exist within the domain and that the mixing of slurries can be impeded by the presence of eddies within the main flow field.
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Näsström, David. "Flow- and concentration variation between the cylinders of a diesel engine." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10175.
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<p>The demands on tomorrows diesel engines regarding fuel consumption and emission levels keep getting more difficult to fulfill. Due to this fact, the control demand is getting bigger and bigger. To be able to comply with the Euro 6 standards, it is believed that engine control need to be conducted individually from cylinder to cylinder if the need for after-treatment systems should be minimized.</p><p>Scania’s approach to handle emission levels so far has been to use exhaust gas recirculation (EGR). To be able to optimize the use of EGR it is necessary to know how the inert gases, water and carbon dioxide, are distributed between the cylinders. The distribution variation become even more difficult to predict since the EGR is cooled, sometimes leading to condensation of some of the water content. The condensation of water and its behavior in the inlet manifold is studied in this thesis.</p><p>Different ways of measuring non-uniformity in the gas composition between cylinders with respect to EGR in general and water content in particular are evaluated. Using these results, measurements have been conducted on an engine and conclusions are drawn from them.</p><p>The conclusions are that uneven distribution of above all liquid water, due to puddle formation, have an impact on emission formation that should be accounted for in some of the examined operating conditions.</p>
8
Yoshida, Hiroaki. "Studies on gas flows between two coaxial circular cylinders on the basis of kinetic theory." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136189.
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Atilgan, Ahmet Koray. "A Study Of Laminar Forced Film Condensation Of Vapor Flowing In Cross-flow Direction Through The Annular Space Between Two Concentric Cylinders." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607714/index.pdf.
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In this study laminar forced film condensation of vapor flowing in cross-flow
direction through the annular space between two concentric cylinders was
investigated numerically. To achieve this, governing equations of the vapor and the
condensate flow in cross-flow direction between two concentric cylinders were
developed. After obtaining the equations in integral forms by using the finite
difference technique the vapor boundary layer thicknesses on the inner and outer
cylinders and the condensate layer thickness was obtained as a function of the
angular position on the cylinders. It was assumed that the condensation took place on
the outer surface of the inner cylinder only and the outer cylinder was assumed to be
insulated. The computer program developed is capable to calculate the condensate
film thickness, vapor boundary layer thickness, the heat flux and the heat transfer
coefficient and the interface velocity between the condensate and the vapor layer as a
function of the angular position on the cylinders. Effects of changing the free stream
velocity flowing in the channel, the radius of the inner cylinder, the temperature
difference between the saturated vapor and the wall and the annular space between
the concentric cylinders were investigated numerically by using the computer
program and the results were presented graphically. Results showed that by
increasing the free stream velocity of the vapor in the core, the film thickness
decreased and by increasing the radius of the inner cylinder, the temperature
difference between the saturated vapor and the wall and the annular space, the film
thickness increased.
10
Handa, Masato. "Studies on the Bifurcation of Flows between Two Coaxial Circular Cylinders on the Basis of Kinetic Theory of Gases." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147648.
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Benbelkacem-Benmouffok, Ghania. "Viscoélasticité et écoulements de fluides structurés." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL012N/document.
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Dans le cadre de cette thèse, nous nous intéressons aux différents comportements de fluides structurés (solutions aqueuses de polymères, suspensions), sous écoulements cisaillés. Dans la première partie, nous donnons une description globale des objets constituant le matériau en utilisant une modélisation structurelle, d'une part et en effectuant des mesures de biréfringence pour qualifier l'anisotropie des objets, d'autre part. A travers la loi tentio-optique, nous montrons que le comportement des objets ne dépend que de la contrainte appliquée. En outre, nous étudions les conditions de mesures objectives pour mener une caractérisation rigoureuse, en comparant des mesures de fluage et d'oscillations et en utilisant une approche analytique. Ce qui va permettre de développer une méthode d'identification des paramètres viscoélastiques et leurs évolutions sous cisaillement, dans le régime linéaire et non linéaire. La deuxième partie concerne les écoulements bidimensionnels de ces fluides dans une géométrie de cylindres coaxiaux centrés et excentrés, à grand entrefer. Le dispositif expérimental est validé par des mesures sur un fluide newtonien. L'objectif est d'étudier le comportement local de différents fluides en utilisant la technique de la PIV. Pour cela, nous réalisons un dispositif expérimental fiable et suffisamment précis pour accéder au champs de vitesse instantané dans tous l'entrefer. Les mesures nous permettent d'accéder à la loi de comportement locale de chaque matériau que nous comparons avec la loi de comportement globale donnée par le rhéomètre dans le cas de la géométrie centrée. De plus, des simulations numériques sur Fluent, ont été effectuées pour compléter notre étude. Les résultats obtenus pour des écoulements laminaires, de différents fluides: newtonien, peu rhéofluidifiant, très rhéofluidifiant, montrent qu'il est possible de décrire et prédire le comportement des fluides newtoniens et faiblement rhéofluidifiants mais les modèles classiques existants dans Fluent ne sont pas capables de décrire le comportement des fluides très rhéofluidifiant qui présentent une très forte hétérogénéité des gradients de vitesse dans l'entrefer<br>Under this thesis, we look at the different behaviors of structured fluids (aqueous solutions of polymers, suspensions) under sheared flow. In the first part, we give a comprehensive description of the items constituting the material using a structural modeling, on the one hand and carrying out birefringence measures to qualify anisotropy objects on the other. Through the tentio-law, we show that the behavior of objects depends only on the applied stress. In addition, we study the conditions of objective measures to conduct a rigorous characterization, comparing creep and oscillations measures, and using an analytical approach. This will help develop a method for identifying viscoelastic parameters and their developments under shear, in both a linear and a no linear regime. The second part concerns the two-dimensional flows of fluids in a coaxial cylinder geometry centered and eccentred, in a wide gap. The objective is to study the local behavior of different fluids using the PIV technic. To do this, we realize an experimental reliable and accurate enough, in all the gap. The experimental device is validated by measurements on a Newtonian fluid. The measures allow to access the local law behavior of each material that we compare with the overall behavior of law given by the rheometer in the case of centered geometry . In addition, digital simulations on Fluent, were made to complement our study. The results for laminar flow, for different fluids: newtonian, little rhéofluidifiant and very rhéofluidifiant, show that it is possible to describe and predict the behavior of some fluid but the existing model in Fluent can not describe the behavior of very rheofluidifiant fluids which have a very strong heterogeneity gradients speed in the gap
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趙遠宏 and Yuen-wang Alex Chiu. "Near wake flow interactions of two square cylinders." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238348.
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Chiu, Yuen-wang Alex. "Near wake flow interactions of two square cylinders /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20297099.
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Kim, Jueun. "A numerical study of the flow around two staggered cylinders." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110497.
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The cross-flow past a pair of staggered circular cylinders is investigated numerically at a Reynolds number of 800 using a 2-D random vortex method. The numerical model was validated at a Reynolds number of 200. A flow around two stationary cylinders was investigated at a Reynolds number of 800 for comparison. Besides staggered configurations, tandem and side-by-side arrangements were also studied for better understanding of a flow around two cylinders.For staggered arrangements, four different cylinder configurations were discussed in the stationary cylinders case. For a small pitch ratio, P/D = 2, at α = 16° the upstream cylinder's inner shear-layer was deflected between the two cylinders and included the separation of the gap shear layer of the downstream cylinder. One Strouhal number of 0.159 was observed in the present study. For a large pitch ratio, P/D = 3.25, at α = 16°, the vortices shed from the upstream cylinder impinge on the downstream one. A single Kármán vortex street is formed behind the downstream cylinder, and therefore, the obtained Strouhal number is very close to that in a single stationary cylinder. At moderate incidence angles, 20° ≤ α ≤ 45°, a pair of vortices was shed via the inner shear-layers of the two cylinders, and then enveloped by the outer shear-layer from the upstream cylinder. This process yields a large combined vortex, which is followed by a vortex shed from the downstream cylinder's outer shear-layer, and multiple Strouhal numbers with an integral relationship. In general, the mean drag coefficient of the downstream cylinder was smaller than that of the upstream cylinder. The negative mean lift coefficients were observed for the downstream cylinder for all configurations considered in this study.<br>L'écoulement transversal a passé une paire de cylindres circulaires quiconces, avec soit un sujet à forcer une oscillation harmonique dans la direction transversale, est étudié numériquement au nombre Reynolds de 800 utilisant une méthode de tourbillonnement en 2 dimensions. Le modèle numérique a été validé au nombre Reynolds de 200. Un écoulement autour de 2 cylindres stationnaires a aussi été étudié au nombre Reynolds de 800 comme comparaison. À part les dispositions quiconces, les dispositions tandem et côte à côte ont aussi été examinées afin de mieux comprendre l'écoulement à l'entour des deux cylindres.Pour les dispositions quiconces, quatre configurations différentes de cylindres ont été préparées dans le cas des cylindres stationnaires. Pour un petit degré de ratio, P / D = 2, à α = 16°, l'intérieur de la couche cisaillée du cylindre en amont a été dévié entre les deux cylindres et a provoqué la séparation de l'écart de la couche cisaillée du cylindre en aval. Un nombre Strouhal de 0,159 a été observé dans la présente étude. Pour un plus grand degré de ratio, P / D = 3,25, à α = 16°, les tourbillons se sont répandus du cylindre en amont pour ensuite empiéter sur celui en aval. Un seul tourbillon de Kàrmàn est formé derrière le cylindre en aval, et donc, le nombre de Strouhal obtenu est très proche de celui d'un seul cylindre stationnaire. Aux angles d'incidence modérée, 20° ≤ α ≤ 45°, une paire de tourbillons s'est répandue via le les couches cisaillées internes des deux cylindres, puis a été enveloppée par le la couche cisaillée externe du cylindre en amont. Cette procédure donne un grand tourbillonnement combiné, qui est suivi par un tourbillonnement répandu par le cylindre de la couche cisaillée externe en aval et les multiples nombres de Strouhal avec une relation intégrale. En général, le coefficient de traînée moyen du cylindre en aval a été plus petit que celui du cylindre en amont. Des coefficients de levage négatifs ont été observés pour le cylindre en aval pour toutes les configurations considérées dans cette étude.
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Ye, Zhengcai. "UV Disinfection between Concentric Cylinders." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14641.
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Outbreaks of food-born illness associated with the consumption of unpasteurized juice and apple cider have resulted in a rule published by the U.S. Food and Drug Administration (FDA) in order to improve the safety of juice products. The rule (21 CFR120) requires manufacturers of juice products to develop a Hazard Analysis and Critical Control Point (HACCP) plan and to achieve a 5-log reduction in the number of the most resistant pathogens. Ultraviolet (UV) disinfection is one of the promising methods to reach this 5-log reduction of pathogens. The absorption coefficients of juices typically vary from 10 to 40 1/cm and can be even higher depending on brand and processing conditions. Thin film reactors consisting of two concentric cylinders are suitable for inactivating pathogens in juices. When the two concentric cylinders are fixed, the flow pattern in the gap can be laminar Poiseuille flow or turbulent flow depending on flow rates. If the inner cylinder is rotating, and the rotating speed of the inner cylinder exceeds a certain value, the flow pattern can be either laminar or turbulent Taylor-Couette flow. UV disinfection between concentric cylinders in laminar Poiseuille flow, turbulent flow and both laminar and turbulent Taylor-Couette flow was investigated experimentally and numerically. This is the first systematic study done on UV disinfection between concentric cylinders in all three flow patterns. The present work provides new experimental data for pathogen inactivation in each of the three flow patterns. In addition, the present study constitutes the first systematic numerical CFD predictions of expected inactivation levels. Proper operating parameters and optimum gap widths for different flow patterns are suggested. It is concluded that laminar Poiseuille flow provides inferior (small) inactivation levels while laminar Taylor-Couette flow provides superior (large) inactivation levels. The relative inactivation levels are: laminar Poiseuille flow < turbulent flow < laminar Taylor-Couette flow.
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Mohany, Atef M. Ziada Samir. "Flow-sound interaction mechanisms of a single and two tandem cylinders in cross-flow." *McMaster only, 2006.
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伍智榮 and Chi-wing Ng. "Interactions of vortices from two circular cylinders in bistable flow regime." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B3123608X.
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Ng, Chi-wing. "Interactions of vortices from two circular cylinders in bistable flow regime /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18037379.
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Sayers, A. T. "Flow interference between groups of three and four equispaced cylinders." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/18696.
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This thesis is a study of the interference forces acting on one cylinder comprising a group of three and four cylinders when situated in a free stream flow. The spacing of the cylinders was such that the lines joining their axes formed an equilateral triangle, and a square respectively. The study is split into two parts, (a) potential flow over the groups of cylinders (b) real flow over the groups of cylinders.
Bound with copies of the authors' published papers.~Bibliography: pages 132-137.
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Medeiros, E. B. "An experimental study of the aeroelastic behaviour of two parallel interfering circular cylinders." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384128.
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Yang, Wenchao. "Two-dimensional Wakes and Fluid-structure Interaction of Circular Cylinders in Cross-flow." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/97563.
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The wake of a bluff body is a representative issue in vortex dynamics that plays a central role in civil engineering, ocean engineering and thermal engineering. In this work, a flowing soap film was used to investigate the wakes of multiple stationary circular cylinders and of a single oscillating cylinder. Corresponding computer simulations were also conducted. Vortex formation of a stationary circular cylinder was analyzed by proper orthogonal decomposition (POD). The POD analysis was used to define an unsteady vortex formation length, which suggests a relationship between the vortex formation length of a single cylinder and the critical spacing of two cylinders in a tandem arrangement. A systematic parametric study of the wake structure was conducted for a controlled transversely oscillating cylinder. Neural network and support vector machine codes assisted the wake classification procedure and the identification of boundaries between different wake regimes. The phase map of the vortex shedding regimes for the (quasi) two-dimensional experiment qualitatively agrees with previous three-dimensional experiments. The critical spacings of two identical tandem circular cylinders in a flowing soap film system were determined using visual inspections of the wake patterns and calculations of the Strouhal frequencies. The dimensionless spacing was both increased and decreased quasi-statically. Hysteresis was observed in the flow patterns and Strouhal numbers. This study appears to provide the first experimental evidence of critical spacing values that agree with published computational results. The wake interaction between a stationary upstream circular disk and a free downstream circular disk was also investigated. With the ability to tie together the wake structure and the object motion, the relationship between energy generation and flow structure in the simplified reduced order model system was studied. The research results find the optimal efficiency of the energy harvesting system by a parametric study.<br>PHD
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Carmo, Bruno Souza. "On wake interference in the flow around two circular cylinders : direct stability analysis and flow-induced vibrations." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4697.
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The flow around two identical circular cylinders, arranged in configurations where one of the cylinders is immersed in the wake of the other, is studied using numerical simulations. Two aspects of such flows were considered. The first is the stability of nominally two-dimensional time-periodic wakes to three-dimensional perturbations. We investigated flows around tandem and staggered arrangements with diverse centre-to-centre distances. Direct stability analysis and numerical simulations were employed, and the results are compared to those obtained for the flow around an isolated cylinder. The onsets of the three-dimensional instabilities were calculated and the unstable modes are fully described. In addition, we assess the nonlinear character of the bifurcations and physical mechanisms are proposed to explain the instabilities. The second aspect considered in this thesis is the flowinduced vibration experienced by a rigid cylinder when it is mounted on an elastic base and immersed in the wake of a fixed identical cylinder. Tandem arrangements with centre-to-centre distances varying from 1.5 to 8 cylinder diameters were tested. The flow was simulated using an Arbitrary Lagrangian-Eulerian approach that coupled the solution of the structure equations with that of the flow. Two- and three- dimensional simulations were performed to assess the mutual influence between the three-dimensional flow structures in the wake and the motion of the cylinder. The response of the downstream cylinder is compared to that of an elastically-mounted rigid isolated cylinder. Based on the simulation results we propose physical mechanisms to explain the origin of the excitation.
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Hall, Oskar. "The flow between two coaxial cones." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486775.
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This thesis provides a study of the flow between two coaxial cones, a geometry with many interesting features and of practical importance. We consider the flow for different driving mechanisms and start by studying the highly viscous flow when the fluid is driven by rotation of the cones or a spherical lid. The solution is found through a low Reynolds number e)...pansion expressed as a combination of forced modes and geometric eigenmodes. The latter may cause an infinite sequence of counter-rotating vortices at the apex of the cones, we study the flow topology for a wide range of parameter values and specify when an infinite sequence of eddies occurs. We also cons.ider the non-axisymmetric Stokes flow where each wave number m gives rise to infinitely many eigeninodes. We map the spectra for different wave numbers and study the relative dominance between the eigenmodes. In contrast to the axisymmetric flow and the flow in one cone, no infinite sequence of eddies occur except in special cases. The solutions to the Stokes equations can be expressed as a symmetric and anti-symmetric part and we consider the response from a moving nonrigid lid, where the .flow exhibits a transition from a flow with closed streamlines to what appears to be a completely chaotic flow. in the second part we consider the flow which results from a point sink situated at the apex of the cones. The problem is reminiscent of the classical Jeffery-Hamel flow. We study the flow in the Stokes limit and find that the similarity solution experiences a break-down for certain cone openings. For a general Reynolds number the governing equations do not admit separable solutions so we consider asymptotic expansions of the flow in a narrow gap limit. In the far field the viscous forces dominate and the flow assumes a parabolic profile, the influence of inertia increases as we move downstream and by computing solutions of a PDE we find the resulting boundary layer flow. In the final chapter we consider the same flow for a slightly different cone geometry where there is a constant gap between the cones. We compare the solutions between the two geometries and discuss their qualitative differences.
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Mekanik, Abolghasem. "General solution for unsteady annular flows between concentric cylinders and annular flow-induced instabilities." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28844.
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The aim of this Thesis is to obtain time-accurate solutions of the Navier-Stokes equations for laminar incompressible unsteady flows generated by oscillating boundaries in an annular region made from two concentric cylinders. For this, a time-dependent coordinate transformation is first used to obtain a fixed computational domain. The resulting governing equations in the fixed domain are discretized in real time based on a three-time-level implicit scheme. A pseudo-time integration with artificial compressibility is then used to reduce the resulting coupled discretized equations in delta form to set a decoupled scalar tridiagonal systems.<br>The method of solution has been applied to various 3-D unsteady flows in annular geometries, as well as to 2-D annular flows. The numerical results obtained are compared with those based on a mean position analysis, without transformation, for small-amplitude oscillation. This comparison shows that the time-dependent coordinate transformation is necessary to obtain accurate solutions for larger-amplitude oscillations.<br>The mean-position approach has also been applied to the analysis of axially variable annular configurations. The results obtained show more pressure recovery after a diffuser section with 6$ sp circ$ half-angle than in the case of 20$ sp circ$ half-angle.<br>A comprehensive experimental study was conducted to validate the theoretical results in the range of laminar flow. The results obtained were in good agreement with the numerical results, specially with those obtained by the time-dependent coordinate transformation. Experiments were also conducted for turbulent flow.<br>Based on the theoretical models developed, a computational method has been used to study fluid-structure interaction phenomena. It was applied to several cylindrical annular configurations in which one side of the annulus, the outer cylinder, is assumed to be flexibly supported, and thus to be susceptible to flow-induced instabilities. The structural and N-S equations were solved simultaneously by employing the numerical method developed for the unsteady flow and a fourth-order Runge-Kutta scheme for the structural motion. The numerical results thus obtained have predicted the stability of the structure for different annular geometries. The structure having a uniform annular geometry was shown to be more damped, while the annular geometry with a backward facing step is less damped. The study of the structure for a uniform annular geometry in the case of the rocking motion of the outer cylinder predicts an instability in the form of flutter of the outer cylinder.
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Gallagher, James Williams. "Stability of axial flow between concentric and eccentric circular cylinders disturbed asymmetrically and nonlinearly." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/12022.
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Zoller, Jürgen. "Added Stiffness Relating to Small Motions of Two Concentric Cylinders Submitted to Axial Annular Incompressible Flow." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31455.
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Axial incompressible, viscous flow is considered in an annular gap between two rigid cylinders. If the cylinders are displaced from their concentric positions in a certain manner, the displacement will cause reaction forces exerted by the fluid pressure. In this investigation the pressure fluctuations caused by the displacement of the structures are approximated by analytical means. Pressure fluctuations in phase with acceleration and velocity of the structure are not calculated here. Stationary flow is considered, because structural displacements are assumed to be small.
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Zoller, Jürgen. "Added Stiffness Relating to Small Motions of Two Concentric Cylinders Submitted to Axial Annular Incompressible Flow." Forschungszentrum Rossendorf, 1996. https://hzdr.qucosa.de/id/qucosa%3A21972.
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Axial incompressible, viscous flow is considered in an annular gap between two rigid cylinders. If the cylinders are displaced from their concentric positions in a certain manner, the displacement will cause reaction forces exerted by the fluid pressure. In this investigation the pressure fluctuations caused by the displacement of the structures are approximated by analytical means. Pressure fluctuations in phase with acceleration and velocity of the structure are not calculated here. Stationary flow is considered, because structural displacements are assumed to be small.
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Park, Sang Hyan. "The effects between two slotted plate flow meter under single, two, three components flow condition." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1522.
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In previous work on the slotted flow meter, repeatibility and reproducibility were
studied under different flow conditions and different configurations. In accordance with
previous work, the effects of the distance between the slotted plate were identified as an
area requring further investigation. The preset 5D distance is expanded to the 10D distance.
The flow coefficient KY, the pressure drop, and the uncertainty analysis is conducted.
There were definite deference in the results between the 5D distance and the 10D distance
in many aspects. As a base line, the flow coefficient KY showed 0.8% ~ 2% difference
between the 5D and the 10D distance case. Depending upon the upstream flow conditions,
the reproducibility of the slotted flow meter was affected. The pressure drop increased as
the upstream Reynolds number increased. The result from the analysis of the water cut
meter showed that there are definite relationships between the parameteres of the water cut
meter and the parameters of the flow.
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OLIVEIRA, DANIELE DIAS DE. "PARTICLE TRANSPORT IN LAMINAR FLOW BETWEEN TWO PARALLEL PLATES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=32757@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>PROGRAMA DE EXCELENCIA ACADEMICA<br>O escoamento de suspensões concentradas tem grande importância em diversos segmentos da indústria, representando uma maneira econômica de transportar grandes quantidades de materiais sólidos particulados. Uma das aplicações inclui a etapa de perfuração de poços de petróleo direcionais. No decorrer do processo são gerados sedimentos originários do corte da formação, que são removidos através da operação de limpeza do poço. Durante a limpeza, no trecho de maior inclinação esses sedimentos tendem a se separar da suspensão, pelo efeito gravitacional, formando um leito na parte inferior do anular. Esse leito formado pode causar vários problemas, como redução da taxa de penetração, desgaste prematuro da broca, prisão da coluna de perfuração, fraturamento da formação e torque excessivo na coluna de perfuração. O entendimento do escoamento de suspensões de partículas se torna relevante para o aperfeiçoamento desses processos. Nesse sentido, o objetivo deste trabalho é analisar o escoamento de suspensões de partículas entre duas placas paralelas para estudar a formação de um leito de sedimentos na parte inferior do canal e determinar o efeito dos diferentes mecanismos de migração de partículas neste processo. A formulação matemática do problema inclui as equações de conservação de massa e quantidade de movimento linear e equação de transporte de partículas. Para descrever o transporte de partículas no escoamento foi usado o modelo de fluxo difusivo proposto por Phillips et al. (1992). As equações diferenciais parciais, que descrevem o escoamento de uma suspensão de partículas, são resolvidas pelo método de Elementos Finitos de Galerkin e o sistema não-linear é resolvido através do método de Newton. Os resultados obtidos mostram como a distribuição das partículas sólidas varia com os parâmetros do problema e determina as condições para a formação de um leito de partículas.<br>The flow of solid particles suspended in a liquid medium have great importance in several industry segments representing an economical way to transport large quantities of solid materials. One of the applications includes the flow during directional well drilling. During the process sediments are generated from the formation cutting, which are removed through the wellbore cleaning. During the cleaning, step near the horizontal section of the well, these sediments tend to separate from the suspension by the action of gravity, forming a stationary bed in the bottom of the annular. This stationary bed can cause problems, such as reducing the penetration rate, premature wear of the drill bit, trapping column, fracturing of the formation and high torque. The complete understanding of the flow of solid particles suspension becomes relevant to the improvement of these processes. In this sense, the main goal of this work is to analyze the flow of solid particle suspensions between two parallel plates to investigate the formation of a stationary bed in the bottom of the channel and to determine the effect of different particle migration mechanisms in this process. The mathematical formulation includes the equations of mass (continuity equation) and momentum conservation. The Diffusive Flux Model proposed by Phillips et al. (1992) was used to describe the particle transport in the flow. The partial differential equations, which describe the flow of solid particles suspension, are solved by the Galerkin/Finite Element Method (GFEM) and the non-linear system is solved using Newton s Method. The results show how the distribution of solid particles varies with the problem parameters and determines the conditions for the formation of a stationary bed.
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ARAUJO, JOSÉ HENRIQUE CARNEIRO DE. "NUMERICAL SIMULATIONS VIA FINITE ELEMENT OF VISCOUS FLOW BETWEEN CONCENTRIC AND ECCENTRIC CYLINDERS WITH ROTATING INNER AND VARIABLE VISCOSITY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19059@1.
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COMISSÃO NACIONAL DE ENERGIA NUCLEAR<br>Efetuou-se um estudo numérico do escoamento entre cilindros concêntricos e excêntricos girantes com efeitos de dissipação viscosa presente. Assumiu-se que o cilindro interno estava girando com uma velocidade angular constante e que o externo estava fixo.
Assumimos a condição de contorno de não deslizamento para velocidade em ambas as paredes. A temperatura do fluido nas paredes dos cilindros foi assumida constante e seu campo assumimos ser governado por efeitos de convecção e condução, com uma fonte de energia proveniente da dissipação viscosa do escoamento. A viscosidade do fluido foi assumida variável com a temperatura. A discretização espacial foi feita por elementos finitos através de funções de base lineares, mais uma função estabilizadora para velocidade no caso dos cilindros excêntricos. O método das características foi usado no problema excêntrico. Resultados computacionais ilustram a eficiência da técnica adotada.<br>A computational study of viscous flow between concentric and eccentrically rotating cylinders in presented in which the effect of viscous dissipation is taken into account.
The inner cylinder is assumed to be rotating at constant speed with respect to the outer one.
We assume a no-alip boundary condition for the velocity on both walls. The temperature of the fluid is assumed to be constant on the cylinders and its distribution is assumed to be governed by both conduction and convection, with a supplementary soure of energy du to the effects of viscous dissipation. The viscosity is assumed to be varies with temperature. The space discretization is based on piecewise linear finite elements, with velocity stabilization in case of the eccentrically cylinders. The method of characteristics is used for time integration in the eccentrically problem. Numerical results illustrate the efficienty of the adopted approach.
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Jakobsson, Hjalmar, and Kasper Karlgren. "Traditional Table vs. Modern Flow Map : A quantitative comparison between two information visualizations." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209662.
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In today’s world we have access to endless amounts of data of varying kind. We would like to be able to display data in a way that actually feels intuitive and not intimidating. The field of information visualization and data visualization has been around for about 40 years attempting to overcome this very problem, and we are still learning more and more about how to visualize different types of data today. One major problem is that there are so many types of data that it is very difficult to make generalizations about how to display certain types of data. In our study we are comparing two specific visualizations with the purpose of wanting to find out if we can draw any types of general rules or guidelines from doing so. The two visualizations we are comparing are a flow map and a tabular visualization depicting interstate migration between US states. Both visualizations show the exact same data but the flow map is a more graphically pleasing representation of the data whilst the tabular visualization looking more like a classic spreadsheet. We have done this by letting 48 people fill in a webform with multiple choice questions. Each participant was randomly assigned either the flow map visualization or the tabular visualization as their aid in filling out the form. Our participants were mainly KTH students and also students that found our study on facebook and deciding to participate. In the past a few qualitative studies have been conducted researching effective methods for visualizing information. However, there is a clear lack in quantitative studies made as far as we know. Therefore we decided to conduct this study attempting to measure the two visualizations performance and compare them against each other. A qualitative part was also included in the web form where we asked our subjects about their experience filling out the form. Our results shows that the flow map outperforms the tabular visualization with regards to both accuracy, efficiency, and perceived difficulty. In a case similar to our study we can conclude that a flow map seems to be the right choice over a traditional tabular visualization. However, one has to bear in mind the context of the study is rather specific. A context where the visualization has other purposes than finding specific answers to simple questions might yield other results. Our main contribution is in methodology, in that we define and implement a low footprint study of interactive data visualisation.<br>Idag har vi tillgång till massvis av data i olika form och vi skulle vilja kunna vissa denna data på ett sätt så att den känns intuitiv och inte skrämmande. Fältet informationsvisualisering har under de senaste 40 åren försökt sig på uppgiften att ta itu med det här problemet, och vi lär oss fortfarande mer och mer om hur vi kan visualisera olika data. Ett huvudproblem är att det finns så många olika typer av data att det är svårt att göra några riktiga generaliseringar om hur data ska visas. I våran studie jämför vi två typer av visualiseringar is syfte att ta reda på om vi kan dra några generaliserade slutsatser eller riktlinjer. De två visualiseringar vi jämför är av typen flödesmapp och klassisk tabulär visualisering skilldrandes migration intärnt mellan olika stater i landet USA. Båda visualiseringarna visar exakt samma data men flödesmappen är mycket mer grafiskt tillfredsställande och den tabulära visualiseringen tenderar att se ut mer som att klassiskt excel-ark. Studien är utförd genom att låta 48 respondenter fylla i en webbenkät med flervalsfrågor som vi har byggt. Varje deltagare har randomt blivit tilldelad en av de två visualiseringarna som hjälpmedel för att kunna svara på frågorna. Deltagarna var till majoriteten KTH-studenter men även andra människor vilka funnit våran studie på facebook. Tidigare har ett antal kvalitativa studier gjorts undersökandes effektiviteten i olika metoder inom informationsvisualisering. Däremot har väldigt få kvantitativa studier gjorts i detta syfte — rättare sagt inga studier så vitt vi kan veta. Därför bestämde vi oss för att göra den studie i vilken vi försöker mäta och ställa de båda visualiseringarna mot varandra. Vi valde att även inkludera en kvalitativ del i studien i vilken våra deltagare kunde beskriva hur de upplevede att fylla i våran webbenkätt. Våra resultat tyder på att flödesmappen är effektivare än den tabulära visualiseringen över lag med hänsyn till både svaren, tiden det tagit att svara, och även den upplevda svårigheten att svara på frågor. I ett liknande fall till vårat skulle vi alltså kunna konstatera att en flödesmapp verkar vara det korrekta valet. Emellertid måsta man ha i åtanke att våran kontext är väldigt specifik. I en annorlunda kontext är sannolikheten stor att resultaten skulle kunna se annorlunda ut. Vårat huvudbidrag med denna studie ligger i metodologin på så vis att vi har definierat och implementerat en slags basal studie i interaktiv datavisualisering.
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Bambrey, Ross R. "Strong interactions between two co-rotating vortices in rotating and stratified flows /." St Andrews, 2007. http://hdl.handle.net/10023/341.
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Rouse, Victoria J. "Comparison of heat transfer and fluid flow characteristics between submerged and free surface jet impingement for two-phase flow." Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1546428292091476.
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Husin, Shuib. "An experimental investigation into the correlation between Acoustic Emission (AE) and bubble dynamics." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7318.
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Bubble and cavitation effects phenomena can be encountered in two-phase gas-liquid systems in industry. In certain industries, particularly high-risk systems such as a nuclear reactor/plant, the detection of bubble dynamics, and the monitoring and measurement of their characteristics are necessary in controlling temperature. While in the petro-chemical engineering industry, such as oil transportation pipelines, the detection and monitoring of bubbles/cavitation phenomena are necessary to minimise surface erosion in fluid carrying components or downstream facilities. The high sensitivity of Acoustic Emission (AE) technology is feasible for the detection and monitoring of bubble phenomena in a two phase gas-liquid system and is practical for application within the industry.
Underwater measurement of bubble oscillations has been widely studied using hydrophones and employing acoustic techniques in the audible range. However, the application of Acoustic Emission (AE) technology to monitor bubble size has hitherto not been attempted. This thesis presents an experimental investigation aimed at exploring AEs from gas bubble formation, motion and destruction. AE in this particular investigation covers the frequency range of between 100 kHz to 1000 kHz.
The AE waveform analysis showed that the AE parameter from single bubble inception and burst events, i.e. AE amplitude, AE duration and AE energy, increased with the increase of bubble size and liquid viscosity. This finding significantly extends the potential use of AE technology for detecting the presence of bubbles in two-phase flow.
It is concluded that bubble activity can be detected and monitored by AE technology both intrusively and non-intrusively. Furthermore, the bubble size can be determined by measurement of the AE and this forms the significant contribution of this thesis.
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Kasapoglu, Serkan. "A Pseudospectral Analysis Of Laminar Natural Convection Flow And Heat Transfer Between Two Inclined Parallel Plates." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606492/index.pdf.
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Three dimensional laminar natural convection flow of and heat transfer in incompressible air between two inclined parallel plates are analyzed with the Boussinesq approximation by using spectral methods. The plates are assumed to be infinitely long in streamwise and spanwise directions. For these directions, periodic boundary conditions are used and for the normal direction constant wall temperature and no slip boundary conditions are used. Unsteady Navier-Stokes and energy equations are solved using a pseudospectral C code in order to obtain velocity and temperature profiles inside the channel. Fourier series are used to expand the variables in x and z directions, while Chebyshev polynomials are used to expand the variables in y direction. By using the temperature distribution between the plates, local and average Nusselt numbers (Nu) are calculated. Nu values are correlated with &<br>#966<br>,which is the inclination angle, and with Racos&<br>#966<br>to compare the results with the literature. Additionally, non-dimensional velocity values and streamlines of the fluid are presented with proper plots.
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Martin, Alex D. "A Convergent Approach to the Continuous Synthesis of Telmisartan via a Suzuki Reaction between Two Functionalized Benzimidazoles." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3750.
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A direct and highly efficient synthesis has been developed for telmisartan, the active ingredient in the widely prescribed antihypertensive drug Micardis®. This approach brings together two functionalized benzimidazoles using a high-yielding Suzuki reaction that can be catalyzed by a homogeneous palladium source or palladium on a solid support.
The ability to perform the cross-coupling reaction was facilitated by the regio-controlled preparation of a 2-bromo-1-methylbenzimidazole precursor. The method developed is the first reported selective bromination at the 2-position of a benzimidazole and produces the first major precursor in high yield (93%). The second precursor, potassium (4-methyl-2-propylbenzimidazol-6-yl) trifluoroborate, was prepared from commercially available 4-bromo-2-methyl-6-nitroaniline. An optimized preparation is described that provides a direct three-step process to prepare the benzimidazole and install the borate; this synthetic sequence yields the second precursor with a 90% yield and no isolated intermediates.
The two prepared precursors were combined with a third, commercially available methyl-4’-(bromomethyl)-[1,1’-biphenyl]-2-carboxylate, utilizing a short sequence of high yielding reactions to produce the telmisartan with an 83% yield from these advanced intermediates. This new convergent approach provides the active drug ingredient with an overall yield of 74% while circumventing many issues associated with the previously reported processes. Additionally, a flow-based synthesis of telmisartan was achieved with no intermediate purifications or solvent exchanges. The continuous process utilizes a tubular reactor system coupled with a plug flow cartridge, ultimately delivering telmisartan in an 86% isolated yield.
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Tsuei, Hi En, and 崔海恩. "The Flow Interference between Two Circular Cylinders." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/60832486156815828056.
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Jane, Sue-June, and 詹淑菁. "Direct Numerical Simulation of Three-Dimensional Flow between two Rotating Cylinders." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/74431784392451324239.
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Atkins, Michael David. "Driving mechanisms of gap flow between two side-by-side circular cylinders." Thesis, 2015. http://hdl.handle.net/10539/17543.
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We present the driving mechanism of gap flow between two stationary side-by-side circular cylinders immersed in the sub-critical Reynolds number regime and its variation with gap spacing, based on steady flow characteristics. A series of experiments and numerical simulations have been performed. Results reveal that gap flow, the flow passing between the cylinders, can be classified broadly into pressure gradient and momentum driven regime, depending on the spacing ratio (T/D) where T is the transverse center-to-center spacing between the cylinders and D is the cylinder diameter. The pressure gradient driven regime occurs roughly T/D < 1.25 where the mean velocity of the gap flow increases as the spacing ratio (T/D) increases. The momentum driven regime follows with a monotonic decrease in the mean velocity as the spacing ratio increases when T/D > 1.25. Within the pressure gradient driven regime, the gap flow undergoes transitions resulting from distinct changes in the circumferential static pressure distribution, velocity profile, the transverse pressure gradient and mean velocity at the throat of the two cylinders.
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Wang, Tse-Chuan, and 王則權. "The Numerical Study of Flows between Two Concentric Rotating Cylinders." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/49700930693593137490.
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碩士<br>國立暨南國際大學<br>土木工程學系<br>91<br>Abstract
An incompressible viscous fluid motion between two concentric rotating cylinders is one of the important subjects in fluid dynamics. These flows are interesting and complex and they are still attracted many by scholars and researchers up to day.
The purpose of this study is to use a numerical method to analysis and simulate the flow patterns and relevant issues of the flows between two concentric rotating cylinders. In the numerical operation, which directly solves the Navier-Stokes equations and continuity equation that are three-dimensional and time-dependent, we deal with the cylindrical coordinates. To analysis and simulate the transitions in the flows between the concentric rotating cylinders, we use a numerical approach which cooperates with third-order accurate up-wind scheme and second-order accurate central difference scheme in a system of uniformed staggered grids. We examine the flow patterns as a function of the Reynolds number, which characterizes the features of these flows, under the conditions that the rotating speeds of the inner and outer cylinders both varied.
In this study we use the above mentioned numerical method to simulate the flows that between infinite rotating concentric cylinders, for example, the Couette flow, the Taylor vortex flow and wavy vortex flow, etc. We make a concise description for these flow patterns that are representative by means of their velocity distributions, streamlines and the type of flows. According to the non-linear theory, we find that the transition from Couette flow to Taylor vortex flow is indeed a typical supercritical bifurcation.
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Chang, Yin-Chang, and 張蔭昌. "Effect of Turbulence Intensity on Flow Interference Between Two Circular Cylinders in Side-by-Side Arrangement." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/74681245009751185195.
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碩士<br>國立海洋大學<br>河海工程學系<br>83<br>In this paper, we present experimental results on wake flow
behind the two side-by-side arranged circular cylinders. The
flow characteristics behind the cylinders are measured for the
different cylinder spacings and different freestream turbulence
intensities. The two cylinders spacings are 1.5D, 2D and 4D.
And the approaching flows are with turbulence intensities I% of
7.38%, 8.03% and 15.86%. The Reynolds numbers Re=UD/υ≒3000.
The cylinder diameter D=0.8 cm. Measurement results have shown
that the turbulence intensity has a marked effect on the
development of wake flow .
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Zakaria, Khaled Yahia [Verfasser]. "Flow interaction and heat transfer between two cylinders in a uniform air stream / von Khaled Yahia Zakaria." 2000. http://d-nb.info/960643664/34.
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Peng-YuanChen and 陳鵬遠. "Analysis of Thermal Hydraulic Characteristics for Thin Film Ribbing and Taylor-Couette Flow between Two Rotating Cylinders." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04873226353219651485.
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博士<br>國立成功大學<br>機械工程學系碩博士班<br>98<br>The ribbing phenomenon and non-uniform film thickness occurred when increasing roll speed and shrinking roll gap in roll coating process, and non-Newtonian property in coating fluid also affected the coating field. It is necessary to analysis the non-Newtonian property of coating fluid, roll speed ratio and roll gap in order to ligten the unstable ribbing. Taylor-Couette flow exists in co-axial rotating electrical equipment such as rotary blade coupling in vehical, and is burned down for high temperature. It is important to improve the thermal behavior in Taylor-Couette flow. In this paper the thermal hydraulic characteristics for thin film ribbing and Taylor-Couette flow between two rotating cylinders were investigated experimentally and numerically.
Non-Newtonian behavior of the roll coating fluid was accounted by using power-law model with power index, n, ranging from 0.8 to 1.2. Effect of roll speed ratio of applicator roll to pick-up roll and gap distance on the coating film thickness and ribbing wavelength were also investigated. The roll gap to radius ratio was within 3.33×10-4 - 6.67×10-4, and the roll speed ratio within 1 - 4. Numerical results were in good agreement with those of experimental data within 5-12%. Results indicated that the film thickness ratios were functions of power-law index, roll speed ratio and ratio of gap distance to roll radius. In forward roll coating process, the coating film thickness to inlet film thickness ratio was reduced as increasing power-law index, and increased as increasing gap to radius ratio and roll speed ratio. In reverse roll coating process, transferred film thickness to inlet film thickness ratio was increased as increasing power-law index and gap to average radius ratio, and decreased as increasing roll speed ratio. The peak pressure in coating flow field was increased as increasing roll speed ratio and power-law index, and reduced as increasing roll gap. The ribbing wavelength-to-gap ratio was reduced as increasing power-law index and capillary number, and enlarged as increasing roll gap. It was shown that the unstable ribbing number was increased as increasing power-law index, capillary number and reducing roll gap.
The thermal-hydraulic characteristics of Taylor-Couette flow in the gap between two horizontal concentric cylinders were investigated. Various radius ratio (η = 0.6, 0.75, 0.9), aspect ratio (A = 1, 5, 10, 15, 20), Prandtl number (Pr = 1, 7, 20, 50, 100), power-law index (n = 0.8-1.2) and rotating Reynolds number (Reω= 390-3900) were evaluated in detail to discuss the effects on Nusselt number. The results indicated that the average Nusselt number of Taylor-Couette flow was increased as increasing rotating Reynolds number, Prandtl number and radius ratio, and decreased as increasing power-law index. The average Nusselt number was affected significantly by aspect ratio A when A≦10, but slightly affected as 10≦A≦20.
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Li, Jing-Yi, and 李兢翌. "Numerical Simulation of Two-Dimensional Flow Past Rectangular Cylinders." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/27038074670827501087.
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ZHAO, JIA-PING, and 趙嘉平. "Stratified flow past two cylinders in tandem arrangement -- Physical experiment." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/19227885305332322204.
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Wang, Li-Ching, and 王立慶. "Numerical study on flow past two cylinders with different diameters." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24365287333787690166.
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碩士<br>國立暨南國際大學<br>地震與防災工程研究所<br>98<br>This article achieves the partial grid encryption by the nest shape grid the effect. The flow field solves it because of the Navier-Stokes equation and the equation of continuity, the explanation logical process uses the method of fractional steps (Fractional Step Method). To unstable, mounts the viscosity and the incompressible flow flow field, for the solution complex boundary, by the nest shape grid explanation flow field process, obstacle of including the complex boundary by the Ravoux et al. [24] development's in inlays the law (Embedding Method) to process it. This article numerical method by has second-order accurate the central committee to insert a minute law to be separated space of item the Navier-Stokes equation, a time aspect using the Adams-Bashforth law processing convection item, by Crank-Nicolson law processing proliferation item. This article first calculates Fang Xingxue the class (Square lid-driven cavity flow) to test this article numerical model validity in the simple boundary flow field. By with Ghia et al. [25] findings compared to right, the result tallies, confirmed that accuracy of this article numerical model, this article and by the different criterion grid computed result, confirmed this article numerical model applies in the simple boundary flow field has second-order accurate. Afterward, this article test inlays the law by Wannier in the Flow to contain utility of the complex boundary flow field. Finally, we apply the nest shape method of lattice to suppress the research in the turbulence transgression flow field.
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Chen, Po-Han, and 陳柏翰. "Collision of Two Circular Cylinders in a Viscous Incompressible Flow." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/xz5a4s.
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碩士<br>國立臺灣大學<br>機械工程學研究所<br>106<br>Problem of fluid-structure interaction is common for nature and industrial applications, and it is a difficult problem. It is also an important challenge for numerical simulation. It does not limit on one solid body for cases that solid move relatively in fluid. It would be possible to collide for multi-bodies moving in fluid. This research aims at developing a collision model with physical meaning, and applying it in simulation of fluid-structure interaction.
We review several existing collision models and summarize advantages and disadvantages of each ones. For the force come from deformation, we derive the elastic term of normal collision force for two-dimensional cylinders of arbitrary shape. We refer to elastohydrodynamic collision to design a proper collision model. With the collision model, the numerical tool, “a spectral element-immersed boundary method for fluid-structure interaction problems”, developed from our lab, is extended to be able to solve multi-body problems.
For the well-known drafting, kissing and tumbling phenomena between two freely falling circular cylinders, we observed equally well in this study. After confirming the accuracy, we adopt the concept of constant acceleration motion in the simulator and explore the flow details of two freely falling circular cylinders. We also compare the velocity difference between one freely falling circular cylinder and two freely falling circular cylinders. In spite of excellent results, a complete model by also taking the tangential component of collision force into consideration will make the proposed collision model more realistic.
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Hung, Tzu-Wei, and 洪梓蔚. "Computation of 3-D Flow for Two aligned Circular Cylinders." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/81241461843131586584.
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碩士<br>國立成功大學<br>水利及海洋工程學系碩博士班<br>93<br>Because of the interaction of separation and multiple vortices between two circular cylinders, the flow through two aligned circular cylinders is more complex then that of a single one. This study attempts to resolve this complex flow field using the commercial software, FLUENT, since it accommodates the completely module of the Reynolds stress model (RSM) for three-dimensional turbulent flow computation. The distance to diameter ratio of the cylinder, and the Reynolds number based on approach velocity and D are the two main parameters that are concerned in the computations.
The model constructed is verified by the experimental data from visualization techniques and the model is then used to simulate flows at Reynolds numbers of 1000 and 5000 and various ratios. The horseshoe vortex, up flow and wake flow existed between two circular cylinders can be simulated clearly at those Reynolds numbers and ratios.
Computed results show that the flows through the aligned circular cylinders are the combinations of the wake flows, the vortex near the water surface and the horseshoe vortex rising from the bottom. The flow features show differently for ratios at 2, 3 and 4, 5. For the flows of the 2 and 3 ratios’, the wake flow generated from the front cylinder interfere with that at the behind, while the distance of the 4, 5 ratios is sufficient that the interferences are lesser than the 2, 3 cases. In addition to these results, the experience gained from the setting up of the computational model using FLUENT can also be a reference for other applications.
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Sung, Yung-lin, and 宋央領. "Numerical simulation of flow induced vibration of two circular cylinders in shear flow." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73405724948000738900.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>97<br>This research is aimed to investigate the fluid-elastic instability of the motion simulation using a single cylinder and two cylinders within the context of shear flows. T/D, shear parameter and mass ratio are parameters to be investigated. Besides, cylindrical motion treks and the amplitude are also analyzed.
Continuity equation and momentum equations are solved alternatively using a CFD package, Fluent 6.3.26. The force caused by the flow interacts with the cylindrical motion. Thus Motion meshing techniques together with the cylindrical motion equations are employed in the simulation. Under different flow conditions, flow types and cylindrical motion models, lock-in and fluid-elastic instability are studied.
The results show that motion and flow types of a single cylinder within the context of the uniform flow have a general agreement with the related literatures. In terms of the shear flow, however, as the shear parameter increases, the fluid-elastic instability is caused, and thus amplitude of the cylinder augments considerably. Further, double cylinders in the shear flow are studied. Double cylinder arrangements( classified as side-by-side and tandem) and the distance between cylinders are the factors to cause fluid-elastic instability. Compared with the single cylindrical motion, double cylindrical motion’s critical flow velocity is smaller than the single cylindrical motion, which means double cylindrical motion are more subject to fluid-elastic instability.
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Huang, Po-Chuan, and 黃柏銓. "Numerical simulation of flow past two circular cylinders of different diameters." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/92124601272542619332.
Full textAbstract:
碩士<br>國立臺灣大學<br>機械工程學研究所<br>96<br>Numerical simulations with unstructured spectral element method were applied to the study of the phenomenon of cross flow around two cylinders. According to the research of Strykowski(1985), vortex shedding could be drastically inhibited with a control cylinder which in size is much smaller compared to the main cylinder. The purpose of this research is further focus on different parameters of control cylinder for drag reducing, lift increasing, and vortex inhibition. The Reynolds number of all simulations is 100. Both passive and active controls were studied. For passive controls, effects of position and gap between two cylinders were systematically investigated and three modes of flow patterns were classified. It was also found that 15% of drag reducing could be achieved at fully inhibition mode and maximum 35% of drag reducing could be achieved at partial inhibition mode. Based on different types of flow patterns, vibration was applied to the control cylinder for active controls. Effects of vibration amplitude and frequency were studied. Due to the transition between subcritical and supercritical flow, the lock-in area at fully inhibition mode is much different than previous literatures.