Дисертації з теми "Fluids motion"
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1
RIBEIRO, GERALDO AFONSO SPINELLI MARTINS. "DYNAMICS OF RELATIVE MOTION BETWEEN SOLID PARTICLES AND NON-NEWTONIAN FLUIDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19130@1.
Повний текст джерелаАнотація:
COMISSÃO NACIONAL DE ENERGIA NUCLEAREste trabalho descreve experimentos relacionamentos com o movimento relativo entre partículas sólidas e fluido não-newtoniano, confinados no interior de um duto circular. Medições da pressão dinâmica adicional, devida unicamente à presença da partícula (fonte de perturbação no escoamento) e do arrasto viscoso foram conduzidas de forma a se verificar a validade da Teoria de Brenner (1962). Esta teoria, já confirmada para fluidos newtonianos, permite que parâmetros característicos do escoamento perturbado sejam determinados, convenientemente, através de parâmetros do escoamento não-perturbado (ausência de partícula). Para o caso de fluido não-newtoniano, denominados puramente viscosos, do tipo Power-law, a teoria se mostrou perfeitamente aplicável. O valor da razão Delta P mais A/D descrito por Brenner foi confirmado com uma precisão de 3 por cento, num total de 70 experimentos realizados. Para fluidos não-newtonianos, viscoelásticos, com função viscosidade tipo Power-law, a validade da teoria parece, entretanto, depender de um parâmetro capaz de descrever na natureza constitutiva do fluido utilizado. Experimentos realizados com três diferentes fluidos viscoelásticos (expoentes power-law n igual 0,303; 0,343; 0,483) conduziram à identificação deste parâmetro, o Segundo Número Elástico, El2. Para valores de El2, inferiores a 14, caracterizando um escoamento predominantemente viscoso, o valor da razão Delta P mais A/D novamente é confirmado com precisão inferior a 4 por cento. Para valores de El2 superiores a 40 a razão Delta P mais A/D não mais pode ser avaliada com base em parâmetros do escoamento perturbado, analogamente ao que havia sido proposto por Brenner para o caso de fluidos newtonianos. Neste trabalho incluem-se também registros contínuos dos experimentos enfatizando os efeitos viscoelásticos envolvidos, bem como uma análise dos efeitos de parede associados ao movimento relativo entre fluidos não-newtonianos e partículas sólidas. Todos os experimentos foram realizados num regime de Reynolds variando de 0,1 a 90 e num regime de Weissenberg (calculando com base no modelo de Powell-Eyring) variando de 850 a 3800.
This work describes experiments related to relative motion between solid particles and mon-newtonian fluid, inside a circular duct. Measurements of the aditional dynamic pressure, due to the presence of the particle (a source of disturbance in the flow) ando f the viscous drag, were conducted to verify the validity of Brenner’s Theory (1962). This theory, already confirmed for newtonian fluids, allows the determination of the characteristic parameters of the disturbed flow using parameters of non-disturbed flow (without particle). In the case of purely viscous non-newtonian fluids, of the power-law type, the theory was confirmed. The value of the ratio Delta P plus A/D, described by Brenner, was confirmed. The value an accuracy of 3 per cent, in a total of 70 experiments. For viscoelastic fluids, with Power-law viscosity function, it appears that the validity of the theory depends on the Second Elastic Number, El2. Experiments conducted with three different viscoelastic fluids (power-law exponents, n equal 0,303; 0,343 and 0,483) shows that for values of El2 bellow 14, which characterizes a predominantly viscous flow, the value of of the ratio Delta P plus A/D is agair confirmed, with na accuracy of 4 per cent. For values of the El2, parameter above 40, the ratio Delta P plus A/D cannot be determined using parameters of the non-disturbed flow, as proposed by Brenner for newtonian fluids. In this work are also included graphic registers of the experiment, showing the complex viscoelastic effects, as well as na analysis of the wall effects associated with the relative motion between non- newtonian fluid and solid particles. All the experiments were conducted with Reynolds number between 0,1 and 90 and a Weissenberg number (based in Powell-Eyring model) between 850 and 38.00.
2
Wang, Jin. "A numerical approach for the interfacial motion between two immiscible incompressible fluids." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092675815.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiii, 152 p.; also includes graphics. Includes bibliographical references (p. 147-152).
3
Anekal, Samartha Guha. "Stokesian dynamic simulations and analyses of interfacial and bulk colloidal fluids." Texas A&M University, 2003. http://hdl.handle.net/1969.1/4434.
Повний текст джерелаАнотація:
Understanding dynamics of colloidal dispersions is important for several
applications ranging from coatings such as paints to growing colloidal crystals for
photonic bandgap materials. The research outlined in this dissertation describes the use
of Monte Carlo and Stokesian Dynamic simulations to model colloidal dispersions, and
the development of theoretical expressions to quantify and predict dynamics of colloidal
dispersions. The emphasis is on accurately modeling conservative, Brownian, and
hydrodynamic forces to model dynamics of colloidal dispersions. In addition, we
develop theoretical expressions for quantifying self-diffusion in colloids interacting via
different particle-particle and particle-wall potentials. Specifically, we have used
simulations to quantitatively explain the observation of anomalous attraction between
like-charged colloids, develop a new criterion for percolation in attractive colloidal
fluids, and validate the use of analytical expressions for quantifying diffusion in
interfacial colloidal fluids. The results of this work contribute to understanding
dynamics in interfacial and bulk colloidal fluids.
4
Lin, Po-Hsien. "Solving First-Order Hyperbolic Problems For Wave Motion in Nearly Incompressible fluids, Two-Phase Fluids, and Viscoelastic Media By the CESE Method." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420552163.
Повний текст джерела
5
Mallett, Michael John Disney. "An analytical and computer modelling study of atomic motion in fluids constrained by barriers." Thesis, University of Kent, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358039.
Повний текст джерела
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Maggistro, Rosario. "On some optimal control problems on networks, stratied domains, and controllability of motion in fluids." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368468.
Повний текст джерелаАнотація:
The thesis deals with various problems arising in deterministic control, jumping processes and control for locomotion in fluids. It is divided in three parts.
The first part is focused on some optimal control problems on network and stratified domains with junctions, where each edge/hyper-plane has its own controlled dynamics and cost. We consider some possible approximations for such a problems given by the use of a switching rule of delayed-relay type and study the passage to the limit when the parameter of the approximation goes to zero. First, we take into account some problems on network: a twofold junction problem, a threefold junction one and an extension of the last one. For each of these problems we characterize the limit functions as viscosity solution and maximal subsolution of a suitable Hamilton-Jacobi problem. Secondly, we consider a bi-dimensional multi-domain problem and as done for the problems on network we characterize the limit function as viscosity solution of a suitable Hamilton-Jacobi problem.
The second part studies a decentralized routing problem over a network, using the paradigm of mean-field games with large number of players. Building on a state-space extension technique, we turn the problem into an optimal control one for each single player. The main contribution is an explicit expression of the optimal decentralized control which guarantees the convergence both to local and to global equilibrium points. Furthermore, we study the stability of the system also in the presence of a delay which we model using an hysteresis operator. As a result of the hysteresis, we prove existence of multiple equilibrium points and analyze convergence conditions.
In the last part of the thesis we investigate different
strategies to overcome the so-called scallop paradox concerning periodic locomotion in fluid. We show how to obtain a net motion exploiting the fluid's type change during a periodic deformation. We consider two different models: in the first one that change is linked to the magnitude of the opening and closing velocity of the scallop's valves. Instead, in the second one it is related to the sign of the above velocity. In both cases we prove that the mechanical system is controllable, i.e. the scallop is able to move both forward and backward using cyclical deformations.
7
Maggistro, Rosario. "On some optimal control problems on networks, stratied domains, and controllability of motion in fluids." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2556/1/PhDThesis.pdf.
Повний текст джерелаАнотація:
The thesis deals with various problems arising in deterministic control, jumping processes and control for locomotion in fluids. It is divided in three parts.
The first part is focused on some optimal control problems on network and stratified domains with junctions, where each edge/hyper-plane has its own controlled dynamics and cost. We consider some possible approximations for such a problems given by the use of a switching rule of delayed-relay type and study the passage to the limit when the parameter of the approximation goes to zero. First, we take into account some problems on network: a twofold junction problem, a threefold junction one and an extension of the last one. For each of these problems we characterize the limit functions as viscosity solution and maximal subsolution of a suitable Hamilton-Jacobi problem. Secondly, we consider a bi-dimensional multi-domain problem and as done for the problems on network we characterize the limit function as viscosity solution of a suitable Hamilton-Jacobi problem.
The second part studies a decentralized routing problem over a network, using the paradigm of mean-field games with large number of players. Building on a state-space extension technique, we turn the problem into an optimal control one for each single player. The main contribution is an explicit expression of the optimal decentralized control which guarantees the convergence both to local and to global equilibrium points. Furthermore, we study the stability of the system also in the presence of a delay which we model using an hysteresis operator. As a result of the hysteresis, we prove existence of multiple equilibrium points and analyze convergence conditions.
In the last part of the thesis we investigate different
strategies to overcome the so-called scallop paradox concerning periodic locomotion in fluid. We show how to obtain a net motion exploiting the fluid's type change during a periodic deformation. We consider two different models: in the first one that change is linked to the magnitude of the opening and closing velocity of the scallop's valves. Instead, in the second one it is related to the sign of the above velocity. In both cases we prove that the mechanical system is controllable, i.e. the scallop is able to move both forward and backward using cyclical deformations.
8
Qu, Bo. "The use of fractional Brownian motion in the modelling of the dispersion of contaminants in fluids." Thesis, Edinburgh Napier University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285235.
Повний текст джерела
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Gross, Andreas [Verfasser], and Christian [Akademischer Betreuer] Wagner. "Investigation of Brownian motion in simple and complex fluids under oscillatory perturbations / Andreas Gross. Betreuer: Christian Wagner." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2014. http://d-nb.info/1058360701/34.
Повний текст джерела
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Aumann, Craig Alvan. "Development, parameterization and numerical solution of an unsaturated flow model for water in the sapwood of a Douglas-fir tree /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/6374.
Повний текст джерела
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Becker, Jan Verfasser], Rudolf [Akademischer Betreuer] Schmitz, and Hans-Jörg [Akademischer Betreuer] [Kull. "Brownian motion of rigid bodies in compressible fluids under nonisothermal conditions / Jan Becker ; Rudolf Schmitz, Hans-Jörg Kull." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1128231662/34.
Повний текст джерела
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Becker, Jan [Verfasser], Rudolf [Akademischer Betreuer] Schmitz, and Hans-Jörg [Akademischer Betreuer] Kull. "Brownian motion of rigid bodies in compressible fluids under nonisothermal conditions / Jan Becker ; Rudolf Schmitz, Hans-Jörg Kull." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1128231662/34.
Повний текст джерела
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Garrett, Jasmine Jay Tamara, and University of Lethbridge Faculty of Arts and Science. "Autobahn : a gene that has a role in auxin influx in Arabidopsis leaves." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/258.
Повний текст джерелаАнотація:
The development of leaf vascular patterns is a highly regulated process. The plant hormone
auxin is critical for vascular patterning: auxin canalization is proposed to cause files of cells to accumulate higher auxin levels and develop into veins. Thus, the response of cells to auxin and transport of auxin are critical to establish proper cell fate. We have characterized a mutation in the Arabidopsis thaliana gene name AUTOBAHN (ABN). abn leaves produce leaves that proliferate disorganized, overlapping veins parallel to the midvein with no differentiation of higher order veins. abn leaves show no normal aspects of the secondary auxin response though double mutant analysis suggest that ABN functions independently of previously characterized auxin response pathways. Wild type plants grown on an influx inhibitor phenocopy abn suggesting that abn is defective in carrier-mediated auxin influx.x, 69 leaves : ill. ; 28 cm.
14
Steynen, Quintin John, and University of Lethbridge Faculty of Arts and Science. "Genetic analysis of leaf vascular patterning in Arabidopsis thaliana." Thesis, Lethbridge : University of Lethbridge, University of Lethbridge. Faculty of Arts and Science, 2001, 2001. http://hdl.handle.net/10133/143.
Повний текст джерелаАнотація:
I have isolated and characterized a recessive mutation in the Forked (FKD) gene that results in the abnormal initiation of vascular bundles in the foliar organs, such that the apices of the vascular bundles initiate freely. Once initiated, the development of Fkd vascular bundles is like wild type, generating an open vascular pattern of similar complexity to the closed venation pattern of wild type. Despite the significant alteration in the vascular pattern, Fkd plants are morphologically indistinct from wild type. fkd mutants do not show altered sensitivity to the effects of auxin and show additive phenotypes with auxin response mutants, suggesting the FKD is part of a pathway acting independently of auxin. The similarity of the open vascular pattern of Fkd plants to that of ancestral vascular plants suggests that acquisition of this pathway may have been critical in the evolution of the closed vascular pattern.x, 55 leaves : ill. ; 28 cm.
15
Cazan, Radu. "Dynamics of swirling flows induced by twisted tapes in circular pipes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33944.
Повний текст джерелаАнотація:
The present study describes the flow characteristics of swirling flows induced by twisted tape inserts in circular pipes. The study is focused on the secondary flow which is investigated experimentally and with numerical models. The results are expected to improve the paper manufacturing process by identifying and removing the detrimental secondary flow. Experimental tests show for the first time the existence of two co-rotating helical vortices superimposed over the main swirling flow, downstream of twisted tapes. The close proximity of the two co-rotating vortices creates a local counter-rotating flow at the pipe centerline. The flow is analyzed using LDV measurements and high speed camera visualization with fine air bubbles seeding which confirm that the helical vortices are stable. After extracting the characteristic tangential velocity profiles of the main vortex and of the two secondary vortices, it was observed that the maximum tangential velocity of all three vortices is the same, approximately half of the bulk velocity. The winding of the helical vortices is in the swirl direction and the pitch of the helical vortices is found to be independent of the inlet velocity. The experimental findings are confirmed by numerical simulations. The numerical results show that the helical vortices originate inside the swirler and evolve from single co-rotating vortices on each side of the tape. The flow characteristics are analyzed in detail. Swirlers with multiple twists and multiple chambers are shown to have less stable secondary motion and could be employed in applications were the secondary motion is detrimental.
16
Titus, Charlene H. A. (Charlene Helecyn Agatha). "Sucrose transporters and sucrose uptake mechanisms in sugarcane." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16448.
Повний текст джерелаАнотація:
Thesis (MSc)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The process of sugar accumulation and transport in sugarcane is still poorly understood. Understanding the processes involved in sucrose transport are important, since membrane transport might be important control points in this pathway. The goals of this project were to unravel the mechanisms of sugar transport in sugarcane culm tissue by using 14C-sugar analysis as well as molecular techniques to identify possible sucrose transporters. Developing (internode 2 and 4) and maturing (internode 8 and 15) culm tissue of sugarcane (Saccharum hybrid) commercial variety N19 was used for all tissue disc experiments. Tissue discs from internodes of different developmental stages were cut from field grown sugarcane plants (cv. N19) and the uptake of 14C-labelled glucose, fructose and sucrose measured. The uptake rates were measured at varying pH, temperature and concentrations of sugars. Hexoses were found to be the major sugar taken up and sucrose was only important when little hexose was available, as was found in the mature ripe internodes. Sucrose uptake differs between tissues and our study showed that sucrose was taken up rapidly at pH 5, similar to the pH optimum of most sucrose transporters Inhibition studies with TRIS (2-amino-2- (hydroxymethyl)-1,3-propanediol) and PCMBS (p-chloromercuribenzenesulphonic acid) indicated that more than one sucrose transporter activity may be present in the sugarcane system at different sucrose concentrations. To date work on sugarcane sucrose transporter expression on DNA and RNA level has been limited. Only recently a sucrose transporter from Saccharum hybrid sugarcane stem cDNA libray, ShSUT1 (Saccharum hybrid Sucrose Transporter ) was isolated and functionally characterized in the yeast strain SEY 6210 (Rae et al., 2004). In an effort to understand sucrose transport in sugarcane culm tissue, a partial sucrose transporter cDNA, ScSUT1(p) from Saccharum hybrid sugarcane a bud cDNA library was isolated, and cloned from a bud cDNA library. The clone was designated ScSUT(p) as a partial Sugarcane Sucrose Transporter. The ScSUT1(p) sequence showed 94% identity to ShSUT1 on nucleotide level over 1258 nucleotides and had an estimated open reading frame of 419 amino acids. Southern blot analysis indicated that the transporter had a low copy number and the ScSUT1(p) transcript expression was constitutive in sucrose accumulating and sucrose storing stem tissue, but was less abundant in immature tissue such as internodes 2 and 3 and in lateral buds. It was concluded that the primary function of ScSUT1(p), was not phloem unloading but that the transporter may be involved in phloem loading, as it is abundant in mature source leaves. ShSUT1 cDNA was obtained from Dr C Grof and the functionality of ShSUT1 as a sucrose transporter in Xenopus leavis oocytes was confirmed. However, electrophysiological measurements on the oocytes demonstrated no measurable current associated with sucrose challenge to the oocytes indicating that the transporter activity was either very low or possibly non-electrogenic. Further investigation is required to characterise the specific mechanism and kinetic properties of this transporter.
AFRIKAANSE OPSOMMING: Die proses van suikerakkumulering en -vervoer in suikerriet word steeds baie vaag verstaan. ‘n Deeglike begrip van die prosessewat betrokke is in die vervoer van sukrose is baie belangrik omdat transmembraan vervoer moontlik een van die belangrike beheerpunte in metabolisme mag wees. Die doelwitte van die studie was om ‘n beter begrip te bekom van die meganisme wat betrokke is by die vervoer en berging van sukrose in suikerriet. Die projek is in ‘n fisiologiese en ‘n molekulêre afdeling verdeel. In die fisiologiese afdeling is stingelweefsel van ‘n Saccharum hybried (variëteit N19) van verskillende stadiums van ontwikkeling (internodes 2-4, internode 8 en internode 15) gebruik. Opname van radioaktiewe (14C) sukrose, glukose en fruktose is as analise metode gebruik vir die suikeropname eksperimente. Die invloed van pH, suiker konsentrasie en inhibitore soos PCMBS (pchloromercuriphenylsulfonic acid) en TRIS (2-amino-2-(hydroxymethyl)-1,3-propanediol) op die tempo van suikeropname is ondersoek. Die molekulêre deel fokus hoofsaaklik op die identifisering, isolering en karakterisering van nuwe sukrose vervoerproteine in suikerriet, met behulp van PCR en heteroloë uitdrukking in Xenopus laevis oösiete. Die 14C - opname eksperimente het tot die volgende gevolgtrekkings gelei: Heksoses speel die belangrikste rol in die vervoer van suiker in die riet as daar min of geen sukrose teenwoordig is nie. Sodra daar sukrose in groot mate teenwoordig is soos in die geval van ontwikkelde, ryp internodes, is die rol van sukrose egter belangriker. Sukrose is die maklikste opgeneem by pH 5, wat naby die pH optimum van die meeste sukrose vervoerproteïene is. TRIS en PCMBS het beide ‘n inhiberende effek op sukrose opname gehad, maar die invloed was groter by die laer sukrose konsentrasies. Tot onlangs was daar baie min inligting oor sukrose vervoer in suikerriet op DNA en RNA vlak. Die eerste sukrose vervoerprotein uit suikerriet, ShSUT1 (Saccharum Hibried Sukrose Transporter) is eers onlangs uit ‘n stingel - cDNA biblioteek geïsoleer (Rae et al., 2004) en die funksionering daarvan is in ‘n gisras (SEY6210) getoets. In my pogings om sukrose vervoer te verstaan is ‘n gedeeltelike cDNA, naamlik ScSUT(p) (partial Sugarcane Sucrose Transporter) van 1258 nukleotiede, uit cDNA afkomstig van suikerrietbotsel geïsoleer. Die nukleotiedvolgorde stem 94% ooreen met ShSUT1 en kodeer vir ‘n moontlike oopleesraam van 419 aminosure. Southern analises het aangedui dat ScSUT(p) ‘n lae kopie getal het, in ooreenstemming met wat vir ander sukrose vervoerproteïene gevind is. Northern analises het getoon dat die uitdrukking van ScSUT(p) konstitutatief is in sukrose akkumulerende sowel as sukrose bergingsweefsel. Jong weefsel (internode 2 en 3) het baie lae uitdrukking getoon, met die hoogste uitdrukking in blaarweefsel. Uit die resultate is afgelei dat ScSUT(p) ‘n rol in floeëmlading en -ontlading mag speel. Xenopus laevis oösiete, is as ‘n heteroloë uitdrukking sisteem gebruik om te bevestig dat ShSUT1 as ‘n sukrose vervoerproteïen funksioneer. Elektrofisiologie het nie daarin geslaag om ShSUT1 se spesifieke werkingsmeganisme te identifiseer nie. Aanduidings is egter gevind dat ShSUT1 moontlik nie as ‘n H+/sukrose simportsisteem werk nie, maar by gefasilliteerde vervoer van sukrose betrokke mag wees. Verdere navorsing is noodsaaklik om die meganisme van ShSUT1 se werking te verstaan.
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Dérian, Pierre. "Wavelets and Fluid Motion Estimation." Rennes 1, 2012. https://ecm.univ-rennes1.fr/nuxeo/site/esupversions/5cdcde8f-715b-4725-a6d4-4eea6474aead.
Повний текст джерелаАнотація:
Ces travaux se situent dans la problématique d'élaboration d'outils de mesure adaptés aux caractéristiques des écoulements fluides. Le développement de l'imagerie digitale, associée à l'utilisation de techniques de visualisation d'écoulements en mécanique des fluides, permet d'envisager l'extraction, à l'aide de méthodes de vision par ordinateur, du mouvement d'écoulements perçu dans des séquences d'images. L'objectif consiste ici à proposer une nouvelle approche de type « flux optique » pour l'estimation multiéchelle de mouvements de fluides, en s'appuyant sur une représentation en ondelettes du mouvement recherché. Cette formulation en ondelettes introduit un formalisme multiéchelle, intéressant tant du point de vue de l'estimation du flux optique que de la représentation de champs de vitesse turbulents. Elle permet en outre la construction de bases à divergence nulle, respectant ainsi une contrainte issue de la physique des fluides. Plusieurs types de régularisation sont présentés; la plus simple procède par troncature de la base aux petites échelles, la plus complexe utilise les coefficients de connexion de la base d'ondelette pour construire des schémas d'ordre élevé. Les approches proposées sont évaluées sur des images synthétiques dans un premier temps, puis sur des images expérimentales d'écoulements caractéristiques. Les résultats obtenus sont comparés à ceux fournis par la méthode usuelle des « corrélations croisées », mettant en avant les intérêts et les limites de l'estimateurThis work falls within the general problematic of designing measurement tools adapted to the specificities of fluid flows. The development of digital imaging, combined with visualization techniques commonly employed in experimental fluid dynamics, enables to extract the apparent flow motion from image sequences, thanks to computer vision methods. The objective is to propose a novel “optical flow” algorithm dedicated to the multiscale motion estimation of fluid flows, using a wavelet representation of the unknown motion field. This wavelet formulation introduces a multiscale framework, conveniently adapted both to the optical flow estimation and to the representation of turbulent motion fields. It enables as well to design divergence-free bases, thereby respecting a constraint given by fluid dynamics. Several regularization schemes are proposed; the simplest consists in truncating the basis at fine scales, while the most complex builds high-order schemes from the connection coefficients of the wavelet basis. Proposed methods are evaluated on synthetic images in the first place, then on actual experimental images of characteristic fluid flows. Results are compared to those given by the usual “cross-correlations”, highlighting the advantages and limits of the wavelet-based estimator
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Venkateshan, Delli Ganesh. "Modeling Fluid Motion over Fibrous Surfaces." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5353.
Повний текст джерелаАнотація:
The ultimate goal of this project has been to develop a computational model for quantifying the interactions between of a body of fluid and a fibrous surface. To achieve this goal, one has to develop a model to create virtual structures that resemble the morphology of a fibrous surface (Objective-1) as well as a model that can simulate the flow of a fluid over these virtual surfaces (Objective-2). To achieve the first objective, we treated fibers as an array of beads interconnected through viscoelastic elements (springs and dampers). The uniqueness of our algorithm lies in its ability to simulate the curvature of the fibers in terms of their rigidity, fiber diameter, and fiber orientation. Moving on to Objective-2, we considered woven screens for their geometric periodicity, as a starting point. We studied how fiber diameter, fiber spacing, and contact angle can affect the skin-friction drag of a submerged hydrophobic woven screen, and how such surfaces resist against water intrusion under elevated hydro-static pressures (a requirement for providing drag reduction benefits). We also studied the impact of surface geometry and wetting properties on droplet mobility over these surfaces. Laboratory experiment was conducted at various stages throughout this investigation, and good agreement was observed between the experimental data and the results from our numerical simulation.
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Ruhnau, Paul. "Variational fluid motion estimation with physical priors." [S.l. : s.n.], 2006. http://madoc.bib.uni-mannheim.de/madoc/volltexte/2007/1432/.
Повний текст джерела
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Wichers, Schreur Bernardus Gerardus Joseph. "The motion of buoyant bodies." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358851.
Повний текст джерела
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Bowman, S. B. "Mathematical aspects of wave motions in stratified fluids." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370240.
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Yang, Seung-Man Leal L. Gary. "Hydrodynamics and Brownian motion of small particles near a fluid-fluid interface /." Diss., Pasadena, Calif. : California Institute of Technology, 1985. http://resolver.caltech.edu/CaltechETD:etd-06302005-124544.
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Lu, Yi, Qinlong Ren, Tingting Liu, Siu Ling Leung, Vincent Gau, Joseph C. Liao, Cho Lik Chan, and Pak Kin Wong. "Long-range electrothermal fluid motion in microfluidic systems." PERGAMON-ELSEVIER SCIENCE LTD, 2016. http://hdl.handle.net/10150/621709.
Повний текст джерелаАнотація:
AC electrothermal flow (ACEF) is the fluid motion created as a result of Joule heating induced temperature gradients. ACEF is capable of performing major microfluidic operations, such as pumping, mixing, concentration, separation and assay enhancement, and is effective in biological samples with a wide range of electrical conductivity. Here, we report long-range fluid motion induced by ACEF, which creates centimeter-scale vortices. The long-range fluid motion displays a strong voltage dependence and is suppressed in microchannels with a characteristic length below similar to 300 mu m. An extended computational model of ACEF, which considers the effects of the density gradient and temperature-dependent parameters, is developed and compared experimentally by particle image velocimetry. The model captures the essence of ACEF in a wide range of channel dimensions and operating conditions. The combined experimental and computational study reveals the essential roles of buoyancy, temperature rise, and associated changes in material properties in the formation of the long-range fluid motion. Our results provide critical information for the design and modeling of ACEF based microfluidic systems toward various bioanalytical applications. (C) 2016 Elsevier Ltd. All rights reserved.
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Chang, Ming. "Example-Based Fluid Simulation." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20310.
Повний текст джерелаАнотація:
We present a novel method for example-based simulation of fluid flow. We reconstruct fluid animation from physically based fluid simulation examples. Our framework shows how to decompose a given series of fluid motion example data into small units and then recompose them. We capture the properties of local fluid behavior by dicing the fluid motion example data into sequences of fragments, which have smaller volume and shorter length. We build a database out of these fragments, and propose a matching strategy to generate new fluid animation. To achieve highly efficient database query, we project our fragments onto lower dimensional subspace using Principal Component Analysis (PCA) approach, and construct our data structure as a kd-tree by treating each fragment as a point in this subspace. Our method has been implemented in synthesizing both two-dimensional (2D) and three-dimensional (3D) fluid’s velocity fields.
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梁偉文 and Wai-Man Leung. "Computational studies on the motion of a stratified fluid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226346.
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Garcia, Gonzalez Jesus. "Numerical analysis of fluid motion at low Reynolds numbers." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/numerical-analysis-of-fluid-motion-at-low-reynolds-numbers(4cf30194-0155-439d-879a-c49787549e8c).html.
Повний текст джерелаАнотація:
At low Reynolds number flows, the effect of inertia becomes negligible and the fluid motion is dominated by the effect of viscous forces. Understanding of the behaviour of low Reynolds number flows underpins the prediction of the motion of microorganisms and particle sedimentation as well as the development of micro-robots that could potentially swim inside the human body to perform targeted drug/cell delivery and non-invasive microsurgery. The work in this thesis focuses on developing an understanding in the mathematical analysis of objects moving at low Reynolds numbers. A boundary element implementation of the Method of regularized Stokeslets (MRS) is applied to analyse the low Reynolds number flow field around an object of simple shape (sphere and cube). It also showed that the results obtained by a boundary element implementation for an unbounded cube, where singularities are presented in the corners of the cube, agrees with more complex solutions methods such as a GBEM and FEM.A methodology for analysing the effect of walls by locating collocation points on the surface of the walls and the object is presented. First at all, this methodology is validated with a boundary element implementation of the method of images for a sphere at different locations. Then, the method is extended when more than one wall is presented. This methodology is applied to predict the velocity filed of a cube moving in a tow tank at low Reynolds numbers for two different cases with a supporting rod similar to an experimental set-up, and without the supporting rod as in the CFD simulations based on the FVM. The results indicate a good match between CFD and the MRS, and an excellent approximation between the MRS and experimental data from PIV measurements. The drag, thrust and torque generated by helices moving at low Reynolds numbers in an unbounded medium is analysed by the resistive force theory, a slender body theory, and a boundary element method of the MRS. The results show that the resistive force theory predict accurately the drag, thrust and torque of moving helices when the resistive force coefficients are calculated from a slender body theory approximation by calculating independently the resistive force coefficients for translation and rotation, because it is observed that the resistive force coefficients depend also of the nature of motion. Moreover, the thrust generated by helices of different pitch angles is analysed calculated by a CFD numerical simulation based on the FVM and a boundary element implementation, an compared with experimental data. The results also show an excellent prediction between the boundary element implementation, the CFD results and the experimental data. Finally, a boundary element implementation of the MRS is applied to predict swimming of a biomimetic swimmer that mimics the motion of E.coli bacteria in an unbounded medium. The results are compared with the propulsive velocity and induced angular velocity measurement by recording the motion of the biomimetic swimmer in a square tank. It is observed that special care needs to be taken when the biomimetic swimmer is modelled inside the tank, as there is an apparent increment in the calculate thrust propulsion which does not represent a real situation of the biometic swimmer which propels by a power supply. However, this increment does not represent the condition of the biomimetic swimmer and a suggested methodology based on the solution from an unbounded case and when the swimmer is moving inside the tank is presented. In addition, the prediction of the free-swimming velocity for the biomimetic swimmer agrees with the results obtained by the MRS when the resistive force coefficients are calculated from a SBT implementation. The results obtained in this work have showed that a boundary element implementation of the MRS produces results comparable with more complex numerical implementations such as GBEM, FEM, FVM, and also an excellent agreement with results obtained from experimentation. Therefore, it is a suitable and easy to apply methodology to analyse the motion of swimmers at low Reynolds numbers, such as the biomimetic swimmer modelled in this work.
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Carvajal, Carlos. "The fluid-coupled motion of micro and nanoscale cantilevers." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35973.
Повний текст джерелаАнотація:
An understanding of the fluid coupled dynamics of micro and nanotechnology has the potential to yield significant advances yet many open and interesting questions remain. As an important example we consider the coupling of two closely spaced cantilevers immersed in a viscous fluid subject to an external driving. While one cantilever is driven to oscillate, the adjacent cantilever is passive. This system is modeled as two simple harmonic oscillators in an array whose motion is coupled through the fluid. Using simplified geometries and the unsteady Stokes equations, an analytical expression is developed that describes the dynamics of the passive cantilever. Full numerical simulations of the fluid-solid interactions that include the precise geometries of interest are performed. The analytical expressions are compared with the numerical simulations to develop insight into the fluid-coupled dynamics over a range of experimentally relevant parameters including the cantilever separation and frequency based Reynolds number. In addition, a shaker-based actuation device is investigated in order to demonstrate its feasibility for use with micro and nanoscale systems.Master of Science
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Leung, Wai-Man. "Computational studies on the motion of a stratified fluid /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23589504.
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Sounart, Thomas L. "Electrokinetic transport and fluid motion in microanalytical electrolyte systems." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279916.
Повний текст джерелаАнотація:
Electrically-driven separation schemes, such as zone electrophoresis (ZE), isotachophoresis (ITP) and isoelectric focusing (IEF), are used profoundly to fractionate mixtures of charged compounds for preparative and particularly analytical applications. Inherent to the separation process is the development of local variations in the electrical conductivity, pH, electric field, etc. One-dimensional, quantitative descriptions of the spatio-temporal evolution of these variations, and their role in the separation process, have been developed over the past two decades. These descriptions lend significant insight into the electromigrational behavior of analytes and buffer components. Nevertheless, because they are one-dimensional, such descriptions omit important effects of electrokinetic fluid motion. The fluid motion arises naturally in the context of the separation scheme, and affects the evolving spatial gradients associated with the separation process. One-dimensional simulations have also been plagued by numerical limitations associated with advection-dominant transport in regions of sharp concentration gradients. In this dissertation, the numerical difficulties are resolved, and a general two-dimensional model of electrokinetic separations is presented. Because the balance laws account for coupling of the velocity field to the ion transport, a variety of processes important to both microfluidic manipulations and analytical separations can be considered. High-ionic strength electroosmotic pumping and field-amplified sample stacking are examined in detail. It is demonstrated that unsteady fluid eddies disperse the gradients in the field variables, and this limits the efficacy of microanalysis processes. Scaling arguments suggest that, at least for simple geometries, approximate solutions to the general model are possible. Semi-analytic approximations are constructed for the fluid velocity v and electric field E, and the parameter space over which they apply is defined. These approximations reduce simulation times by about two thirds, and provide general information on the dominant physics in microanalysis processes. The scale analysis and simulation results demonstrate that although cross-sectional conductivity gradients meet or exceed those in the axial direction, the electric field is essentially unidirectional. Also, at sufficiently high electric field strengths (ca. several hundred V/cm), nonlinear electrohydrodynamic stresses begin to influence the fluid motion. Finally, if the electrical stresses are negligible, the semi-analytic solutions for v and E permit 1-D macrotransport representations of the solute transport. Effective 1-D simulations yield cross-sectionally averaged values for the field variables in orders of magnitude less simulation time than 2-D simulations.
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Mazumdar, Dipak 1932. "Fluid flow, particle motion and mixing in ladle metallurgy operations." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72064.
Повний текст джерелаАнотація:
Extensive computer predictions have been carried out by the author to study flow, addition dispersion and particle motion during central gas injection into cylindrical vessels. In conjunction with numerical computations, experiments were conducted in a 0.30 scale water model of a 150 ton steel processing ladle, using a Froude number scaling criterion. Two typical gas injection configurations (i.e., conventional central injection and C.A.S. alloy addition procedure) were investigated.Flow visualization studies were carried out using a suspended network of silken threads, mean velocity vectors and overall flow patterns were determined by video recording techniques, while mean velocity vectors and associated turbulence level were also measured with laser doppler velocimetry. These measurements show very reasonable agreement with equivalent numerical predictions.
To simulate the subsurface motion of additions, spherical wooden balls of various densities were dropped from typical heights, and their subsurface trajectories, immersion times, etc., recorded by means of a video recorder. Frame by frame analysis of the video tapes showed trends which are in good accord with computed trajectories.
Mixing times of simulated molten additions were measured by the conductivity measurement technique. These were compared with prediction from an equivalent tracer dispersion model and excellent agreement achieved.
For industrial application, flow, particle motion, and mixing times in a 150 ton steel processing ladle have been predicted and their technological significance discussed.
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Korzhova, Valentina N. "Motion Analysis of Fluid Flow in a Spinning Disk Reactor." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/3478.
Повний текст джерелаАнотація:
The ow of a liquid _lm over a rapidly rotating horizontal disk has numerous industrial applications including pharmaceuticals, chemical engineering, bioengineering, etc. The analysis and control of complex uid ows over a rapidly rotating horizontal disk is an important issue in the experimental uid mechanics. The spinning disk reactor exploits the bene_ts of centrifugal force, which produces thin highly sheared _lms due to radial acceleration. The hydrodynamics of the _lm results in excellent uid mixing and high heat or mass transfer rates.
This work focuses on developing a novel approach for uid ow tracking and analysis. Speci_cally, the developed algorithm is able to detect the moving waves and compute controlling _lm ow parameters for the uid owing over a rotating disk. The input to this algorithm is an easily acquired non-invasive video data. It is shown that under single light illumination it is possible to track specular portion of the reected light on the moving wave. Hence, the uid wave motion can be tracked and uid ow parameters can be computed. The uid ow parameters include wave velocities, wave inclination angles, and distances between consecutive waves. Once the parameters are computed, their accuracy is analyzed and compared with the solutions of the mathematical uid dynamics models based on the Navier-Stokes equations for the case of a thin _lm. The uid model predicts wave characteristics based on directly measured controlling parameters, such as disk rotation speed and uid ow rate. It is shown that the calculated parameter values approximately coincide with the predicted ones. The average computed parameters were within 5 � 10% of the predicted values.
In addition, given recovered uid characteristics and uid ow controlling parameters, full 3D wave description is obtained. That includes 3D wave location, speed, and distance between waves, as well as approximate wave thickness.
Next, the developed approach is generalized to model-based recovery of uid ow controlling parameters: the speed of the spinning disk and the initial uid-ow rate. The search in space for model parameters is performed as to minimize the error between the ow characteristics predicted by the uid dynamics model (e.g. distance between waves, wave inclination angles) and parameters recovered from video data. Results demonstrate that the speed of a disk and the ow rate are recovered with high accuracy. When compared to the ground truth available from direct observation, we noted that the controlling parameters were estimated with less than 10% error.
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Rogers, Charles. "Computational Fluid Dynamics Analysis of an Ideal Anguilliform Swimming Motion." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1940.
Повний текст джерелаАнотація:
There is an ongoing interest in analyzing the flow characteristics of swimming fish. Biology has resulted in some very efficient motions and formulating these motions is of interest to engineers. One such theory was written by Dr. William Vorus and Dr. Brandon Taravella involving ideal efficiency. It is therefore interesting to test the calculations to see if it is possible to design a motion that can create thrust without necessarily creating vorticity. The computational fluid dynamics software of ANSYS Fluent was used to calculate the resulting flow field of the eel motion to compare with the theoretical values.
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Kalogiannis, Konstantinos. "Behaviour of elastohydrodynamic films subjected to oscillatory motion." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/44542/.
Повний текст джерелаАнотація:
The main aim of this research was to understand the influence of vibration of machine components on lubricating films formed in high-pressure contacts. In the current investigation Spacer Layer Imaging Method has been used to monitor the response of elastohydrodynamic films subjected to lateral and vertical vibrations. For both cases the EHL contact was produced by steel or tungsten carbide ball and a transparent disc which was made of glass or sapphire, loaded against each other. The contacting side of the disc was sputtered with a thin chromium layer and a silica spacer layer. White light was shown onto the contact through a specially built microscope. The interferometric fringes formed by the rays reflected by the chromium layer and by the ball's surface are captured by a high speed CCD camera. The images were subsequently analyzed and converted to film thickness maps according to calibration curves. During the tests conducted under lateral vibrations the effect of several parameters including the frequency of lateral motion, Hertzian pressure, temperature variation and the main entrain speed were investigated. Results have shown that lateral oscillations create ripples through the lubricant film only at highest lateral frequency and low entraining speeds. The parameter which influences the formation of the perturbations in the film is the ratio between the main rolling speed and the lateral speed of the contact. The smaller the ratio the larger the transient phenomena can be identified. It has also been found that temperature change has no significant influence upon the film behaviour. The effect of vertical vibrations on the film thickness was also investigated. The analysis of the film thickness has shown that a sudden increase of load had an effect of increasing the contact diameter and at the same time modified the convergence in the inlet, an enhanced film thickness was produced at the inlet periphery of the initial contact zone and travel through the contact at a velocity equal to the average speed of the contacting surfaces.
34
Zainy, Mohammed. "Hydrodynamic modelling of cerebrospinal fluid motion within the human ventricular system." Thesis, Nottingham Trent University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272855.
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Idowu, Olusola Clement. "Hydrodynamics of coupled normal-fluid and superfluid motion in helium II." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323480.
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Heminger, Michael Alan. "Dynamic Grid Motion in a High-Order Computational Aeroacoustic Solver." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1272550725.
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Forster, Graham Keith. "Instability and wave-growth within some oscillatory fluid flows." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/14087.
Повний текст джерелаАнотація:
Oscillatory fluid flows arise naturally in many systems. Whether or not these systems are stable is an important question and external periodic forcing of the flow may result in rich and complicated behaviours. Here three distinct oscillatory fluid flows are examined in detail, with the stability of each being established using a range of analytical and computational methods. The first system comprises standing surface capillary-gravity waves in second-harmonic resonance subject to Faraday excitation. Using the perturbation technique of multiple scales, the amplitude equations for the system are derived. At exact resonance, and with the absence of damping, the only fixed point of the equations is found to be the origin. A computational approach reveals that the amplitudes of the two waves remain either bounded or grow to infinity depending on initial data. With the introduction of detuning and damping into the system families of fixed points now exist and some special cases are considered. The second class of flows are unbounded time-periodic flows with fixed ellipsoidal stream surfaces, and having spatially uniform but time-periodic strain rates. Using a recently developed method based on theoretical study of the Schrodinger equation with quasi-periodic potential, a computational approach is adopted which determines the stability of the flow to three-dimensional plane wave disturbances. Results for the growth rate and winding number of the disturbance clearly reveal the regions of instability. It is found that almost all these flows are highly unstable. The third class is another set of three-dimensional time-periodic flows with spatially uniform strain rates. These flows are non-axisymmetric and have sinusoidally-fluctuating rates of strain directed along the fixed coordinate axes. The same computational method is employed and it is found that instability increases along with the non-axisymmetric nature of the flow.
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Kurishina, Victoria. "Fluid nonlinearities for calibrated VIV wake oscillator models." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237154.
Повний текст джерелаАнотація:
Onshore and offshore structures are subject of strict safety regulations, and acceptable design implies requirements for accurate models of potentially dangerous phenomena. The phenomenon of Vortex-Induced Vibrations (VIVs) develops when a slender structure interacts with a fluid flow. Vortices grow in the disturbed boundary layer and spread behind the structure, resulting in fluctuations of the fluid forces acting on the body. Slender structures are present almost everywhere in the form of tall buildings and skyscrapers, cranes, antennas, power lines, suspension bridges, umbilicals, risers and free spans of pipelines which deliver water, oil and gas. The deeper in the water and higher in the sky these structures are, more likely they can experience VIVs and the lock-in state due to the exposure to various flow profiles. The wake oscillator method allows to model fluid variables during VIV lock-in using self-excited and self-limited oscillators of Van der Pol or Rayleigh type. In this research, the capabilities of alternative nonlinear oscillators as fluid equations are considered for modelling elastically supported rigid structures with one and two degrees-of-freedom in uniform flow. For modelling two-dimensional flexible structures in uniform and sheared flows, new wake oscillator models are developed in this work and applied with alternative damping terms. The dynamics of the uniform flow model of flexible structure is investigated in detail with the focus on coexisting solutions of the displacement amplitudes. Empirical coefficients for wake oscillator models are calibrated in this study using constrained nonlinear minimization and experimental data available in the literature. The validation performed confirms the most successful results for the suite of models of 2DOF rigid structure for low mass ratio, where agreement with both in-line and cross-flow displacement records was obtained.
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Rodriguez, Carlos Guillermo. "Three dimensional flow analysis by the vortex-lattice method /." This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040555/.
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Warrilow, Ian Mark. "Some sedimentation problems in Stokes flow." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/848546/.
Повний текст джерелаАнотація:
This thesis explores a number of hydrodynamic sedimentation problems in which the fluid motion is governed by the quasi-steady Stokes approximation. In Chapter Two potential-theoretic methods are used to solve the axisymmetric sedimentation problem of a small slowly rotating and translating particle moving through a fluid-filled circular pore of finite length. In such an approach the velocity and pressure fields, governing the fluid motion, are expressed in terms of relevant harmonic functions, a method which is also applicable to linear elasticity. To give the motivation behind the selection of these harmonics and the analytic methods used, Chapter One discusses two electrostatic problems possessing analogous boundary conditions. In both chapters each problem is reduced to the solution of coupled infinite systems of linear equations and solved by truncation to coupled finite sets. The numerical solutions of these equations are then used to compute approximations to the resistive torque and drag experienced by the sedimenting particle. Chapter Three is divided into two parts. Part I treats the application of the method of subareas to some model electrostatic problems. In Part II we utilize the Oseen integral representation of solutions of the Stokes equations to develop a boundary-integral method for the study of further sedimentation problems. The method involves the discretization of the linear integral equations of the first kind, whose unknowns comprise boundary-stress components, using the method of subareas, thus reducing the integral equations to a system of linear equations. Problems solved using this method include the axial translation of a small particle towards a rigid square plate, an investigation of the flow field development for an axially translating small body moving through a hollow and constricted circular cylinder of finite length, the broadside motion of a circular disk through a circular cylinder and an investigation of a curious phenomenon, known as 'overshooting', in the developing axial velocity profile within a finite-length circular cylinder, given certain inlet and outlet velocity profiles.
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Endres, Derek. "Development and Demonstration of a General-Purpose Model for Brownian Motion." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1307459444.
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Hägglund, Jesper. "Simulated cerebrospinal fluid motion due to pulsatile arterial flow : Master Thesis Project." Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-182508.
Повний текст джерелаАнотація:
All organs, including the brain, need a pathway to remove neurotoxic extracellular proteins. In the brain this is called the glymphatic system. The glymphatic system works by exchanging proteins from interstitial fluids to cerebrospinal fluids. The extracellular proteins are then removed through the cerebrospinal fluid drains. The glymphatic system is believed to be driven by arterial pulsatility, cerebrospinal fluid production and respiration. Cerebrospinal fluids enters the brain alongside arteries. In this project, we investigate if a simulated pulsatile flow in a common carotid artery can drive cerebrospinal fluid flow running along the artery, using computational simulations of a linearly elastic and fluid-structure multiphysical model in COMSOL. Our simulations show that a heartbeat pulse increases the arterial radius of the common carotid artery by 6 %. Experimental data, assessed using 4D magnetic resonance imaging of a living human, show an increase of 13 %. Moreover, our results indicate that arterial displacement itself is not able to drive cerebrospinal fluid flow. Instead, it seems to create a back and forth flow that possibly could help with the protein exchange between the cerebrospinal and interstitial fluids. Overall, the results indicate that the COMSOL Multiphysics linearly elastic model is not ideal for approximations of soft non-linearly elastic solids, such as soft polydimethylsiloxane and artery walls work for stiffer materials. The long term aim is to simulate a part of the glymphatic system and the present work is a starting point to reach this goal. As the simulations in this work are simplified there are more things to test in the future. For example, using the same geometries a non-linear elastic model could be tested. The pulsatile waveform or the geometry could be made more complex. Furthermore the model could be scaled down to represent a penetrating artery in the brain instead of the common carotid artery.
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Tyszka, J. Michael. "Visualisation of slow and medium speed fluid motion using magnetic resonance imaging." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240122.
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Ma, Ye, and 马烨. "Lagrangian mass transport induced by wave motions in biological systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hdl.handle.net/10722/205828.
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Rayer, Quintin G. "An experimental investigation of heat transfer by large scale motions in rotating fluids." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306077.
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Pathak, Saurabh. "Quantification Of Internal Droplet Motion Using Particle Image velocimetry For Various Engineering Problem." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619458988178314.
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47
Hayes, E. R. "The prediction of droplet motion and breakup using a vortex model for turbulent flows." Thesis, Cranfield University, 1988. http://dspace.lib.cranfield.ac.uk/handle/1826/10285.
Повний текст джерелаАнотація:
This document describes the development of a computational model to
study the movement and breakup _of droplets in turbulent
two-component flows. The aim is to produce a suitable model which
will be economical of computing resources and practical for
engineering applications. The application of particular interest
here is that of water droplets in fully developed turbulent pipe
flows of oil.
The computational method uses Vortex filaments to produce, in a
novel way, instantaneous fluctuating velocities within the flow
domain. The trajectory of a particle within this field is predicted
by integrating the theoretical law of motion for the particle.
In addition, the breakup of a fluid particle in the turbulent field
may be predicted using an empirical criterion formulated using data
obtained from a series of experiments. The tests were designed to
study the deformation and breakup of a single water droplet in oil
subjected to shear.
Wherever possible the results of each development stage of the model
were compared with work published in the literature.
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Carberry, Josie. "Wake states of a submerged oscillating cylinder and of a cylinder beneath a free-surface." Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7678.
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Watson, John Paul. "Numerical simulation of vortex breakdown in an enclosed circular cylinder." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/16868.
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Geller, Anthony S. Leal L. Gary. "A study of the creeping motion of a sphere normal to a deformable fluid-fluid interface : deformation and breakthrough /." Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03192008-135633.
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