Dissertations / Theses on the topic 'Flow visualization'
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Li, Liya. "Advanced flow visualization." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196263993.
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LI, Liya. "Advanced flow visualization." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1196263993.
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Stange, Yuri. "Visualization of Code Flow." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162108.
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Visual representation of Control Flow Graphs (CFG) is a feature available in many tools, such as decompilers. These tools often rely on graph drawing frameworks which implement the Sugiyama hierarchical style graph drawing method, a well known method for drawing directed graphs. The main disadvantage of the Sugiyama framework, is the fact that it does not take into account the nature of the graph to be visualized, specically loops are treated as second class citizens. The question this paper attempts to answer is; how can we improve the visual representation of loops in the graph? A method based on the Sugiyama framework was developed and implemented in Qt. It was evaluated by informally interviewing test subjects, who were allowed to test the implementation and compare it to the normal Sugiyama. The results show that all test subjects concluded that loops, as well as the overall representation of the graph was improved, although with reservations. The method presented in this paper has problems which need to be adressed, before it can be seen as an optimal solution for drawing Control Flow Graphs.Visuell representation av flödesscheman (eng. Control Flow Graph, CFG) är en funktion tillgänglig hos många verktyg, bland annat dekompilerare. Dessa verktyg använder sig ofta av grafritande ramverk som implementerar Sugiyamas metod för uppritning av hierarkiska grafer, vilken är en känd metod för uppritning av riktade grafer. Sugiyamas stora nackdelär att metoden inte tar hänsyn till grafens natur, loopar i synnerhet behandlas som andra klassens medborgare. Frågeställningen hos denna rapport är; Hur kan vi förbättra den visuella representationen av loopar i en graf? En metod som bygger vidare på Sugiyama-ramverket utvecklades och implementerades i Qt. Metoden testades genom att hålla informella kvalitativa intervjuer med testpersoner, vilka fick testa implementeringen och jämföra den med den vanliga Sugiyama-metoden. Resultaten visar att alla testpersonerna stämmer in på att loopar, så väl som den overskådliga representionen av grafen förbättrades, dock med vissa reservationer. Metoden som presenteras i denna rapport har vissa problem, vilka bör adresseras innan den kan ses som en optimal lösning för uppritning av flödesscheman.
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Wilms, Jeffrey. "Flow visualization of cavitation." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/32158.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Mohammad Hosni
A typical refrigeration loop is composed of an evaporator, compressor, condenser, and an expansion valve. There are many possible refrigerants that can be used, but the physical properties of water make it ineffective in the traditional refrigeration loop. But if water could be used it would have many advantages as it is abundant, cheap, and is safe for the environment. This research focuses on a different kind of refrigeration loop using water. This new refrigeration loop utilizes water flowing through a nozzle, initiating cavitation. Cavitation is generally defined as creating vapor from liquid, not through adding heat, but by decreasing the pressure. In a converging/ diverging nozzle, as the cross sectional area is constricted, the velocity of the flow will increase, decreasing the pressure. Therefore, by flowing water through the nozzle it will cavitate. Transforming liquid into gas requires a certain amount of energy, defined as the latent heat. When a liquid is turned to vapor by an increase in the temperature, the latent heat is provided by the heat transfer to the system. As no energy is being added to the nozzle to cause the cavitation, the energy transfer to create the vapor comes from the remaining liquid, effectively causing a temperature drop. This research focused on the flow visualization of water cavitating as it travelled through a converging/ diverging nozzle. Under different flow conditions and different nozzle geometries, the cavitation manifested itself in different formations. When gasses were entrained in the water they formed bubbles, which acted as nucleation sites as they moved through the nozzle. This was called travelling bubble cavitation. In venturi nozzles the cavitation nucleated off of the wall, forming attached wall cavitation. When water flowed out of an orifice, a turbulent mixture of liquid and vapor, orifice jet, was formed which caused vapor to form around it. This was known as shear cavitation. When the water was rotated prior to the throat of an orifice, the orifice jet expanded radially and formed swirl cavitation. In addition to studying how the cavitation was formed, the void fraction and velocity were measured for attached wall cavitation.
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Chlebanowski, Joseph S. "Flow visualization by laser sheet/." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23237.
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A flow visualization system using smoke and a laser sheet for illumination has been designed and developed for use in the 32- x 45-inch low speed wind tunnel. Major design features include a portable smoke rake designed for ease of installation and removal, the use of fiber optics to transport the laser light in a safe and convenient manner, and a portable traversing mechanism to traverse and orient the laser light sheet. The capabilities of the flow visualization system have been demonstrated by producing qualitative photographic recordings of complex flow patterns past an airfoil model and a missile model. Keywords: Flow visualization; Smoke; Laser sheet; Fiber optics; Theses
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Hixson, Roy Lester. "Flow visualization on a small scale/." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23239.
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A quarter scale model of the planned renovated form of an existing flow visualization tunnel was designed and constructed to test the quality of flow and for small scale research and flow visualization demonstrations. Three flow visualization techniques were developed, including fog injection, helium bubbles, and smoke wire. In addition to velocity calibration and test section mapping of the tunnel, the latter two of these methods were used for visualizing flows around three different shaped bodies as demonstration that the tunnel's design objectives were realized. Both techniques produced excellent photographic results of flows around a block of rectangular cross section, a circular cylinder and an airfoil. (Theses)
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Barrett, Michael John Sheiko Sergei. "Molecular visualization of individual molecules during flow." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2942.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2010.Title from electronic title page (viewed Jun. 23, 2010). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
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El-Khatib, Jasmine. "Flow visualization for a micro air vehicle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/MQ53322.pdf.
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Eazzetta, Benedict A. "Flow visualization of the human abdominal aorta." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/17800.
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Yakhshi, Tafti Ehsan. "FLOW VISUALIZATION IN MICROFLUIDIC EXPANSION AND MIXING." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3121.
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Micro particle image velocimetry (microPIV) is a non-intrusive tool for visualizing flow in micron-scale conduits. Using this investigative instrument, two experimental studies were performed to understand flow behaviors in microfluidic channels - a sudden expansion step flow and laminar velocity profile variation in diffusion driven mixing. First, flow in a backward facing step feature (1:5 expansion ratio) in a microchannel was taken as the subject of microPIV flow visualization. The onset and development of a recirculation flow was studied as a function of flow rate. This flow pattern was further used to investigate two major parameters affecting microPIV measurements; the depth-of-focus and recording time-intervals between images in a microPIV image pair. The onset of recirculation was initiated at flow rates that correspond to Reynolds numbers, Re>95, which is well beyond the typical working range of microfluidic devices (Re=0.01-10). The recirculation flow has a 3D structure due to the dimensions of the microchannel and the effect of no slip condition on the walls. Ensemble cross-correlation was found not to be sensitive to variations of depth-of-focus and the output flow fields were similar as long as the overall optical focus remained within the upper and lower bounds of the microchannel. However, variations of time intervals between images in a microPIV pair, resulted in quantitatively and qualitatively different flow patterns for a given constant flow rate and depth-of-focus. In the second experiment, the effect of the laminar velocity profile and its variation on mixing phenomena at the reduced scale is studied. It is shown that the diffusive mass flux between two miscible streams, flowing in a laminar regime in a microchannel, is enhanced if the velocity at their diffusion interface is increased. Based on this idea, an in-plane passive micromixing concept is proposed and implemented in a working device (sigma micromixer). This mixer shows considerable mixing performance by periodically varying the flow velocity profile, such that the maximum of the profile coincides with the transversely progressing diffusion fronts repeatedly throughout the mixing channel. microPIV has been used to visualize the behavior of laminar flow inside the micromixer device and to confirm the periodic variation of the velocity profile through the mixing channel.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering MSME
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Ames, Danielle 1974. "Shear flow visualization at high Reynolds Numbers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50478.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1998.Includes bibliographical references (leaves 92-94).
The mechanisms responsible for various disturbances in the wakes of ships have been investigated for some time. Efforts to define and characterize the contributing factors and resulting turbulent wake manifestations conclude that ship length, speed and geometry play integral and interdependent roles. Previous experimentation in the Ocean Engineering Towing Tank at MIT on small scale model ships supplied data for Reynold's Numbers up to ~ 0(106). The work included in this thesis represents a continuation of those efforts up to Re O(107) using a model DDG51 (5514) Destroyer. Through endeavors to identify wake phenomena and closely examine possible sources, previously unvisualized charicteristics were revealed and the calibration, comparison and validation of numerical simulations were made possible. Experimental efforts were concentrated on the study of flow in the wake and near the bow of the model DDG-51 Destroyer (5514). Qualitative and quantitative flow visualization methods were adapted, designed and implemented including ship-fixed and tank fixed streak videography and Digital Particle Image Velocimetry (DPIV). In addition, the experimental apparatus was modified for similar flow visualization near live fish, and a description of this endeavor and its progress are included.
by Danielle Ames.
S.M.
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Picot, Paul A. "Blood flow visualization and flow rate estimation with colour Doppler ultrasound." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32324.pdf.
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Wiebel, Alexander. "Localized flow, particle tracing, and topological separation analysis for flow visualization." Doctoral thesis, Aachen : Shaker, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016959033&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Sytsma, Michael J. "Aerodynamic flow characterization of micro air vehicles using flow visualization methods." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015755.
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Butler, Jason Edward. "Tomographic imaging for the visualization of multiphase flows /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Born, Silvia. "Illustrative Flow Visualization of 4D PC-MRI Blood Flow and CFD Data." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-154354.
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Das zentrale Thema dieser Dissertation ist die Anwendung illustrativer Methoden auf zwei bisher ungelöste Probleme der Strömungsvisualisierung. Das Ziel der Strömungsvisualisierung ist die Bereitstellung von Software, die Experten beim Auswerten ihrer Strömungsdaten und damit beim Erkenntnisgewinn unterstützt. Bei der illustrativen Visualisierung handelt es sich um einen Zweig der Visualisierung, der sich an der künstlerischen Arbeit von Illustratoren orientiert. Letztere sind darauf spezialisiert komplizierte Zusammenhänge verständlich und ansprechend zu vermitteln. Die angewendeten Techniken werden in der illustrativen Visualisierung auf reale Daten übertragen, um die Effektivität der Darstellung zu erhöhen. Das erste Problem, das im Rahmen dieser Dissertation bearbeitet wurde, ist die eingeschränkte Verständlichkeit von komplexen Stromflächen. Selbstverdeckungen oder Aufrollungen behindern die Form- und Strömungswahrnehmung und machen diese Flächen gerade in interessanten Strömungssituationen wenig nützlich. Auf Basis von handgezeichneten Strömungsdarstellungen haben wir ein Flächenrendering entwickelt, das Silhouetten, nicht-photorealistische Beleuchtung und illustrative Stromlinien verwendet. Interaktive Flächenschnitte erlauben die Exploration der Flächen und der Strömungen, die sie repräsentieren. Angewendet auf verschiedene Stromflächen ließ sich zeigen, dass die Methoden die Verständlichkeit erhöhen, v.a. in Bereichen komplexer Strömung mit Aufwicklungen oder Singularitäten. Das zweite Problem ist die Strömungsanalyse des Blutes aus 4D PC-MRI-Daten. An diese relativ neue Datenmodalität werden hohe Erwartungen für die Erforschung und Behandlung kardiovaskulärer Krankheiten geknüpft, da sie erstmals ein dreidimensionales, zeitlich aufgelöstes Abbild der Hämodynamik liefert. Bisher werden 4D PC-MRI-Daten meist mit Werkzeugen der klassischen Strömungsvisualisierung verarbeitet. Diese werden den besonderen Ansprüchen der medizinischen Anwender jedoch nicht gerecht, die in kurzer Zeit eine übersichtliche Darstellung der relevanten Strömungsaspekte erhalten möchten. Wir haben ein Werkzeug zur visuellen Analyse der Blutströmung entwickelt, welches eine einfache Detektion von markanten Strömungsmustern erlaubt, wie z.B. Jets, Wirbel oder Bereiche mit hoher Blutverweildauer. Die Grundidee ist hierbei aus vorberechneten Integrallinien mit Hilfe speziell definierter Linienprädikate die relevanten, d.h. am gefragten Strömungsmuster, beteiligten Linien ausgewählt werden. Um eine intuitive Darstellung der Resultate zu erreichen, haben wir uns von Blutflußillustrationen inspirieren lassen und präsentieren eine abstrakte Linienbündel- und Wirbeldarstellung. Die Linienprädikatmethode sowie die abstrakte Darstellung der Strömungsmuster wurden an 4D PC-MRI-Daten von gesunden und pathologischen Aorten- und Herzdaten erfolgreich getestet. Auch die Evaluierung durch Experten zeigt die Nützlichkeit der Methode und ihr Potential für den Einsatz in der Forschung und der KlinikThis thesis’ central theme is the use of illustrative methods to solve flow visualization problems. The goal of flow visualization is to provide users with software tools supporting them analyzing and extracting knowledge from their fluid dynamics data. This fluid dynamics data is produced in large amounts by simulations or measurements to answer diverse questions in application fields like engineering or medicine. This thesis deals with two unsolved problems in flow visualization and tackles them with methods of illustrative visualization. The latter is a subbranch of visualization whose methods are inspired by the art work of professional illustrators. They are specialized in the comprehensible and esthetic representation of complex knowledge. With illustrative visualization, their techniques are applied to real data to enhance their representation. The first problem dealt with in this thesis is the limited shape and flow perception of complex stream surfaces. Self-occlusion and wrap-ups hinder their effective use in the most interesting flow situations. On the basis of hand-drawn flow illustrations, a surface rendering method was designed that uses silhouettes, non-photorealistic shading, and illustrative surface stream lines. Additionally, geometrical and flow-based surface cuts allow the user an interactive exploration of the surface and the flow it represents. By applying this illustrative technique to various stream surfaces and collecting expert feedback, we could show that the comprehensibility of the stream surfaces was enhanced – especially in complex areas with surface wrap-ups and singularities. The second problem tackled in this thesis is the analysis of blood flow from 4D PC-MRI data. From this rather young data modality, medical experts expect many advances in the research of cardiovascular diseases because it delivers a three-dimensional and time-resolved image of the hemodynamics. However, 4D PC-MRI data are mainly processed with standard flow visualizaton tools, which do not fulfill the requirements of medical users. They need a quick and easy-to-understand display of the relevant blood flow aspects. We developed a tool for the visual analysis of blood flow that allows a fast detection of distinctive flow patterns, such as high-velocity jets, vortices, or areas with high residence times. The basic idea is to precalculate integral lines and use specifically designed line predicates to select and display only lines involved in the pattern of interest. Traditional blood flow illustrations inspired us to an abstract and comprehensible depiction of the resulting line bundles and vortices. The line predicate method and the illustrative flow pattern representation were successfully tested with 4D PC-MRI data of healthy and pathological aortae and hearts. Also, the feedback of several medical experts confirmed the usefulness of our methods and their capabilities for a future application in the clinical research and routine
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Narrow, Taryn Lea. "Flow visualization within a seven-rod micro-bundle." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17525.
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Darmofal, David L. (David Louis). "Hierarchal visualization of three-dimensional vortical flow calculations." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/44269.
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Wisby, C. "Real-time digital imaging techniques for flow visualization." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/848586/.
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A real-time digital imaging technique has been applied to smoke flow visualized turbulent flows to provide statistical data concerning bluff body wakes. The 'digital imaging technique' has been successfully applied to the wake of a two-dimensional flat plate, circular cylinder and a jet in a crossflow configuration. A detailed study of the two-dimensional flat plate model involved comparative hot-wire and pressure measurements combined with data from previously published experimental investigations. The results obtained included, intermittency measurements, vortex shedding spectral analyses (autocorrelations), spatial correlations, wake interface statistics and turbulence data. In the majority of cases, the digital imaging technique was found to provide excellent quantitative detail whilst also offering some unique wake interface statistics. The experiments conducted on the circular cylinder model revealed details of secondary vortex shedding and their base-bleed dependence, whilst the jet in a crossflow configuration enabled the imaging technique to be applied to a complex, three-dimensional flow model. The resulting iso-intermittency contour map was produced expediently, and within an experimental period far shorter than could be expected for single-location probe measurements. In addition to the above-outlined quantitative technique, real-time digital imaging was also applied more qualitatively to the study of dynamic stall on an aerofoil and to the enhancement of high-speed vapour-screen visualizations, both techniques offering the possibility for enhanced quantitative flow studies in future investigations. Finally, true-colour video digitisation has been exploited in a preliminary study of the quantification of global surface shear stress values using liquid crystal technology. Although in its infancy, the realisation of an experimental procedure along such lines would be of immense benefit to experimental aerodynamic research.
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Burr, Janice E. "Jet mixing : the role of numerical flow visualization /." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12162009-020204/.
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Chua, Weng Heng. "Flow visualization studies over a UCAV 1303 model." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Jun/09Jun%5FChua.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Chandrasekhara, M. S. "June 2009." Description based on title screen as viewed on July 10, 2009. Author(s) subject terms: Unsteady Aerodynamics, UCAV Maneuvers, 2D-unsteady flows. Includes bibliographical references (p. 43-44). Also available in print.
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Nguyen, Phong Hai. "Statistical flow data applied to visual analytics." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-70978.
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Statistical flow data such as commuting, migration, trade and money flows has gained manyinterests from policy makers, city planners, researchers and ordinary citizens as well. Therehave appeared numerous statistical data visualisations; however, there is a shortage of applicationsfor visualising flow data. Moreover, among these rare applications, some are standaloneand only for expert usages, some do not support interactive functionalities, and somecan only provide an overview of data. Therefore, in this thesis, I develop a web-enabled,highly interactive and analysis support statistical flow data visualisation application that addressesall those challenges.My application is implemented based on GAV Flash, a powerful interactive visualisationcomponent framework, thus it is inherently web-enabled with basic interactive features. Theapplication uses visual analytics approach that combines both data analysis and interactivevisualisation to solve cluttering issue, the problem of overlapping flows on the display. A varietyof analysis means are provided to analyse flow data efficiently including analysing bothflow directions simultaneously, visualising time-series flow data, finding most attracting regionsand figuring out the reason behind derived patterns. The application also supportssharing knowledge between colleagues by providing story-telling mechanism which allowsusers to create and share their findings as a visualisation story. Last but not least, the applicationenables users to embed the visualisation based on the story into an ordinary web-pageso that public stand a golden chance to derive an insight into officially statistical flow data.
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Edmunds, Matthew. "Stream surface seeding for flow visualisation." Thesis, Swansea University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678585.
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Ouyang, Q. "Asymmetric flow over cones at high incidence." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233135.
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Wiebel, Alexander [Verfasser]. "Localized Flow, Particle Tracing, and Topological Separation Analysis for Flow Visualization / Alexander Wiebel." Aachen : Shaker, 2008. http://d-nb.info/1161304282/34.
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Gustafsson, Filippa. "Visualization and Quantification of Helical Flow in the Aorta using 4D Flow MRI." Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132152.
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Due to the complex anatomy of the heart, heart valves and aorta, blood flow in the aorta is known to be complex and can exhibit a swirling, or helical, flow pattern. The purpose of this thesis is to implement methods to quantify and visualize both the speed of helicity, referred to as the helicity density, and the direction of helicity, which is measured by the localized normalized helicity. Furthermore, the relationship between helicity and geometrical aorta parameters were studied in young and old healthy volunteers. Helicity and geometrical parameters were quantified for 22 healthy volunteers (12 old, 10 young) that were examined using 4D Flow MRI. The relation between helicity and the geometry of the aorta was explored, and the results showed that the tortuosity and the diameter of the aorta are related to the helicity, but the jet angle and flow displacement do not appear to play an important role. This suggests that in healthy volunteers the helical flow is primarily affected by the geometry of the aorta, although further trials should be performed to fully characterize the effects of aortic geometry. The results also show that the helicity changes with age between the two age groups and some of the geometrical parameters also has a significant difference between the age groups.
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Bordoloi, Udeepta Dutta. "Importance-driven algorithms for scientific visualization." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118952958.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xiv, 126 p.; also includes graphics. Includes bibliographical references (p. 119-126). Available online via OhioLINK's ETD Center
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Ayers, James T. "Hydrodynamic Drag and Flow Visualization of IsoTruss Lattice Structures." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd782.pdf.
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Lau, Alexis Kai-Hon. "Automated two dimensional flow visualization and coherent structure recognition." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/25883.
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This paper describes an efficient method for extracting quantitative data from time sequences of fluid flow images. It also introduces a computer automated method for the identification of coherent structures in turbulent flow fields. This method eliminates subjective manual judgement in the crucial stage of coherent structure recognition.
The surface motion on turbulent grid flow (Reynolds number 10") was visualized by recording images of tracer particles on a video tape. Each video frame was then digitized as a binary image using a microcomputer. By tracking and connecting the tracer paths through successive frames using a mainframe computer the flow history was reconstructed. Streak trajectories were then fitted by polynomials to give various flow parameters of interest over desired flow times. In particular the linear and angular velocities were determined as scatter points from which mesh fields were interpolated. Coherent structures were identified by thresholding the field of angular velocity. Using the interpolated mesh fields of linear velocities, each coherent structure was parametrized with the properties of size, average linear and angular velocities, and energy content. The flow dynamics and interactions are then discussed using these structure properties. The system was developed primarily to enhance data recognition for a new model of turbulence based on the energetics of coherent structures. It is also intended as a general technique to be used for other flow visualization and coherent structure studies. Applying the system to the initial stage of grid turbulence, it successfully recognized over 80% of all the coherent structures manually identified. Parameter results using these automatically identified structures were compared with established results and model predictions. Limitation and possible improvement on the present two dimensional system is discussed. Various aspects in extending the system to a three dimensional environment are also presented.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Szymczak, Michel. "Flow visualization of cavitating, high-speed, submerged water jets." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5159.
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Gopal, Madan. "Visualization and mathematical modelling of horizontal multiphase slug flow." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1173979842.
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White, Samuel Scott. "Visualization of flow phenomena in a vascular graft model." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/16887.
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Brydges, Bruce E. "Flow visualization of dynamic stall on an oscillating airfoil." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27060.
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Cortina, Díaz Marta. "Flow boiling heat transfer and visualization in narrow channels /." Düsseldorf : VDI-Verl, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=017035574&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Cortina, Diaz Marta. "Flow boiling heat transfer and visualization in narrow channels." Düsseldorf VDI-Verl, 2007. http://d-nb.info/99200179X/04.
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Grigorescu, Fredriksson Alexandru. "Blood flow specific assessment of ventricular function : Visualization and quantification using 4D flow CMR." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143417.
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The spectrum of cardiovascular diseases is the leading cause of morbidity and mortality globally. Early assessment and treatment of these conditions, acquired as well as congenital, is therefore of paramount importance. The human heart has a great ability to adapt to various hemodynamic conditions by cardiac remodeling. Pathologic cardiac remodeling can occur as a result of cardiovascular disease in an effort to maintain satisfactory cardiac function. With time, cardiac function diminishes leading to disease progression and subsequent heart failure, the end-point of many heart diseases, associated with very poor prognosis. Within the normal cardiac ventricles blood flows in highly organized patterns, and changes in cardiac configuration or function will affect these flow patterns. Conversely, altered flows and pressures can bring about cardiac remodeling. In congenital heart disease, even after corrective surgery, cardiac anatomy and thereby intracardiac blood flow patterns are inherently altered. The clinically most available imaging technique, ultrasound with Doppler, allows only for one-directional flow assessment and is limited by the need of clear examination windows, thus failing to fully assess the complex three-dimensional blood flow within the beating heart. Cardiovascular magnetic resonance imaging (CMR) with phase-contrast has the ability to acquire three-dimensional (3D), three-directional time resolved velocity data (3D + time = 4D flow data) from which visualization and quantification of blood flow patterns over the complete cardiac cycle can be performed. Four functional blood flow components have previously been defined based on the blood route and distribution through the ventricle, where the inflowing blood that passes directly to the outflow is called Direct flow. From these components, various quantitative measures can be derived, such as component volumes and kinetic energy (KE) throughout the cardiac cycle. In addition, the 4D flow technique has the ability to quantify and visualize turbulent flow with increased velocity fluctuations in the heart and vessels, turbulent kinetic energy (TKE). The technique has been developed and evaluated for assessment of left ventricular (LV) blood flow in healthy subjects and in patients with dilated dysfunctional left ventricles, showing significant changes in blood flow patterns and energetics with disease. There is however still no study addressing the gap in the spectrum from the healthy cohorts to patients with moderate to severe left ventricular remodeling. In Paper III, 4D flow CMR was utilized to assess LV blood flow in patients with subtle LV dysfunction, and a shift in blood flow component volumes and KE was seen from the Direct flow to the non-ejecting blood flow components. In patients with both left- and right-sided acquired and congenital heart disease, right ventricular (RV) function is of great prognostic significance, however this ventricle has historically been somewhat overseen. With its complex geometry, advanced physiology and retrosternal location, assessment of the RV is still challenging and the right ventricular blood flow is still incompletely described. In Paper I, the RV blood flow in healthy subjects was assessed, and the proportionally larger Direct flow component was located in the most basal region of the ventricle and possessed higher levels of KE at end-diastole than the other flow components suggesting that this portion of blood was prepared for efficient systolic ejection. In Paper II, the blood flow was assessed in the RV of patients with subtle primary LV disease, and even if conventional echocardiographic or CMR RV parameters did not show any RV dysfunction, alterations of flow patterns suggestive of RV impairment were found in the patients with the more remodeled LVs. With improvements of the cardiovascular health care, including the surgical techniques, the number of adult patients with surgically corrected complex congenital heart diseases increases, one of which is tetralogy of Fallot (ToF). Surgical repair of ToF involves widening of the pulmonary stenosis, which postoperatively may cause pulmonary insufficiency and regurgitation (PR). Disturbed or turbulent flow patterns are rare in the healthy cardiovascular system. With pathological changes, such as valvular insufficiency, increased amounts of TKE have been demonstrated. Turbulence is known to be harmful to organic tissues and could be significant in the development of ventricular remodeling, such as dilation and other complications seen in Fallot patients. In Paper IV, the RV intraventricular TKE levels were assessed in relation to conventional measures of PR. Results showed that RV TKE was increased in ToF patients with PR compared to healthy controls, and that these 4D flow-specific measures related slightly stronger to indices of RV remodeling than the conventional measures of PR. 4D flow CMR analysis of the intracardiac blood flow has the potential of adding to pathophysiological understanding, and thereby provide useful diagnostic information and contribute to optimization of treatment of heart disease at earlier stages before irreversible and clinically noticeable changes occur. The flow specific measures used in this thesis could be utilized to detect these alterations of intracardiac blood flow and could thus act as potential markers of progressing ventricular dysfunction, pathological remodeling or used for risk stratification in adults with early repair tetralogy of Fallot. Visualizations of intracardiac flow patterns could provide useful information to cardiac/thoracic surgeons pre- and post-operatively.
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Piri, Hossein. "Flow visualization in 3D printed PEM fuel cell bipolar plates." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62259.
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In recent years, due to the public concern on global warming, both increasing energy efficiency and developing green energy become crucially important. Fuel cells can be one of the most suitable clean energy solutions for the environment because of its high energy conversion efficiency and near zero emissions of criteria air pollutants at the use stage. To increase the energy efficiency of fuel cells, effectively utilize the Pt catalyst and increase the fuel cell durability, the uniform distribution of the reactants over the fuel cell active area is of great importance. Over the last decade, many researchers have focused on developing flow field design to homogenously distribute the reactant and to decrease the pressure drop in the bipolar plates. However, most of the previous studies are in the stage of numerical simulation, and the few experimental studies have used very simple flow field geometries. Not to mention that complex transport phenomena inside a fuel cell make even the numerical simulation challenging and time consuming, which hinders the quick screening of proposed modifications and new designs.
While the conventional fabrication techniques are expensive and time consuming, 3D printing is a very good rapid prototyping method that can be used both to validate the simulation results and to supplement the tedious simulation work. The question is whether the results from 3D printed flow fields could be as accurate and reliable as flow fields fabricated with conventional methods.
In the present research, we investigated the applicability of 3D printing in validating the simulation results and as a fast screening method. State of the art designs for anode, cathode and water cooling BPPs proposed and fabricated using Polyjet 3D printing, SLA 3D printing and laser-cutter technologies and the pressure drop and velocity profiles were measured for each plate. The results demonstrated that SLA 3D printing has great promises to serve as a screening tool in modifying the flow field design, as well as in validating the simulation results.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Satija, Aman. "Development of a high speed three-dimensional flow visualization technique." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/SATIJA_AMAN_1.pdf.
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Moore, James E. Jr. "Steady and pulsatile flow visualization in the human abdominal aorta." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16351.
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Weber, Amanda Clare. "Visualization and quantitative measurements of flow within a perfused bioreactor." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16907.
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Nguyen, Trong Tin 1979. "Development of blood analogs for flow visualization and hemolysis investigations." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82624.
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The experimental investigation of blood flow using in vitro models is very important to derive relevant and quantitative information in order to understand the biomechanical conditions resulting from blood flow dynamics. Furthermore, such studies can help us analyze and evaluate flow disturbances caused by pathologies and by cardiovascular prostheses such as aortic valves and left ventricular assist devices (LVAD). For example, these disturbances can range from high shear flow regions causing blood hemolysis to low shear regions resulting in plaque deposition. Flow visualization studies represent a family of methods to study fluid flow through cardiovascular hydraulic models using blood analogs. Thus, for these analogs, two of the main fluid mechanical properties to be reproduced are the bulk kinematic viscosity and shear-thinning of blood. In a first approach, a blood model is developed to simultaneously match the kinematic viscosity of blood and the refractive index of the material of the cardiovascular model for flow visualization experiments. In a second approach, the development of a non-Newtonian blood analog is presented to match the shear-thinning behavior of blood. This approach also allows the development of a blood analog with hemolytic properties. (Abstract shortened by UMI.)
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Zhao, Amy (Xiaoyu Amy). "Applying video magnification techniques to the visualization of blood flow." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99799.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-94).
In this thesis, we investigate the use of video magnification for the visualization and assessment of blood flow. We address the challenge of low signal-to-noise ratios in video magnification by modeling the problem and developing an algorithm for measuring the SNR in the context of video magnification. We demonstrate that the algorithm can be used to estimate the SNR of a real video and predict the SNR in the magnified video. We use several techniques based on video magnification to visualize the blood flow in a healthy hand and a hand with an occluded artery, and show that these visualizations highlight differences between the hands that might be indicative of important physiological differences.
by Amy (Xiaoyu) Zhao.
S.M.
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Chen, Chun-Ming. "Data Summarization for Large Time-varying Flow Visualization and Analysis." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469141137.
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GERKE, Kirill Mironovich. "Visualization and Quantification of Preferential Flow Paths in Forested Hillslopes." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/124375.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第14210号
理博第3344号
新制||理||1492(附属図書館)
UT51-2008-Q679
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 SIDLE Roy Cal, 教授 千木良 雅弘, 教授 石川 裕彦
学位規則第4条第1項該当
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Kuppa, Subrahmanyam. "Visualization and velocity measurement of unsteady flow in a gas generator using cold-flow technique." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54226.
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Modeling of internal flow fields with hot, compressible fluids and sometimes combustion using cold flow techniques is discussed. The flow in a gas generator has been modeled using cold air. Experimental set up was designed and fabricated to simulate the unsteady flow with different configurations of inlet tubes. Tests were run for flow visualization and measurement of axial velocity at different frequencies ranging from 4 Hz to 12 Hz. Flow visualization showed that the incoming flow was a complex jet flow conformed to a cylindrical enclosure, while the outgoing flow resembled the venting of a pressurized vessel. The pictures show a complex flow pattern due to the angling of the jet towards the wall for the bent tube configurations and straightened flows with straight tube and other configurations with straighteners. Velocity measurements were made at an inlet Re of 8.1 x 10⁴ based on maximum velocity and inlet diameter using a single sensor hot wire anemometer at several locations in the plane of the inlet tube at 4 Hz, 8 Hz and 12 Hz for the straight tube and bent tube inlet configurations. The axial velocity near the entrance showed a strong component of the forcing frequency. Phase averaged mean velocities were observed to be well defined during charging and diminished during venting inside the cylinder. The jet flow penetrated most for the 4 Hz and least for the 12 Hz case. For the straight tube inlet comparison with a steady flow measurement of sudden expansion flow showed a qualitative similarity of the mean axial velocity distribution and centerline velocity decay during the charging phases. For the bent tube inlet case the contour plots showed the flow tendency towards the wall. Two cells were seen in the contours for the 8 Hz and 12 Hz cases. The deviation of the point of occurrence of maximum velocity in a radial profile was found to be about 6.5°. Entrance velocity profiles showed symmetry for the straight tube inlet while were skewed for the bent tube inlet. Contour plots of the phase averaged axial turbulence intensity for bent tube cases showed higher values in the core and near the wall in the region of impingement. Axial turbulence intensity measured for the straight tube case showed features as observed in an axisymmetric sudden expansion flow.Ph. D.
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Ahmed, Zayed. "Quantitative flow measurement and visualization of cavitation initiation and cavitating flows in a converging-diverging nozzle." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35522.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
B. Terry Beck
Mohammad H. Hosni
Cavitation is the formation of vapor phase from the liquid phase by reduction in its absolute pressure below the saturation pressure. Unlike boiling, where the temperature of the liquid is increased to cause vaporization, the reduction in the pressure alone can cause the liquid to turn into vapor. Cavitation is undesirable in many engineering applications as it is associated with reduction in efficiency and is known to cause damage to pump and propeller components. However, the endothermic nature of cavitation could be utilized to create a region of low temperature that could be utilized to develop a new refrigeration cycle. The work presented in this thesis is part of ongoing research into the potential cooling capacity of cavitation phenomena, where the cavitation in a converging-diverging nozzle is being investigated. Due to the constricting nature of the throat of the converging-diverging nozzle, the liquid velocity at the throat is increased, obeying the continuity law. With an increase in velocity, a reduction in absolute pressure is accompanied at the throat of the nozzle according to the Bernoulli’s principle. The local absolute pressure at the throat can go lower than the saturation vapor pressure, thereby causing the fluid to cavitate. The effect of water temperature on the flowrates, the onset of cavitation within the nozzle, and the resulting length of the cavitation region within the nozzle are the subject of this thesis. Experimental results and analysis are presented which also show that near the onset of cavitation, the flowrate can go beyond the choked flowrate, causing the local pressure in the throat to go well below zero for an extended amount of time in the metastable state, before nucleating (cavitating) into a stable state. Flow visualization using a high speed digital camera under different operating conditions was aimed at investigating the region of cavitation onset, which appears to be associated with boundary layer separation just downstream of the nozzle throat. In order to delay the boundary layer separation point in the downstream section of the nozzle, the diffuser region of the nozzle was modified to enable two flow paths, where one path would suck the flow near the inner walls of the nozzle and the other would allow the bulk of the flow to pass through. This was achieved with the use of inserts. Various inserts were tested in an attempt to capture the effect of inserts on the cavitation phenomena. Their effect on the flowrates, length of two phase region, and cavitation onset are presented in this thesis.
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Vlachos, Pavlos P. "An Experimental Spatio-Temporal Analysis of Separated Flows Over Bluff Bodies Using Quantitative Flow Visualization." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28675.
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In order to study three-dimensional unsteady turbulent flow fields such as the wakes of bluff bodies, a Digital Particle Image Velocimetry (DPIV) system was developed. This system allows non-intrusive two-dimensional and time varying velocity measurements. Software and hardware modifications necessary to enhance the capabilities of the system were preformed, resulting in increased frequency resolution. However, due to hardware limitations and limitations inherited from the implementation of the method, space resolution is reduced. Subsequently, digital image processing tools to improve the space resolutions were developed. The advantages and limitations of the method for the study of turbulent flows are presented in detail.
The developed system is employed in the documentation of time-varying turbulent flow fields. Initially we study the spanwise variation of the near wake of a low-aspect ratio, surface-mounted, circular cylinder piercing a free surface. The asymmetry of the end conditions combined with the natural unsteadiness of the vortex shedding generates a very complex flow filed which is difficult to study with conventional methods. By employing the aforementioned system we are able to reveal a departure of the two-dimensional character of the flow in the form of oblique vortex shedding. The effect of free surface on the vortex formation length and on the vortex reconnection process is documented. Near the free surface the alternate mode of vortex shedding is suppressed, leading to simultaneous shedding of vortices in the wake. Indications of vortex dislocations and change of the vortex axis in order to reconnect to the free surface are observed. Finally, a novel approach of reconstructing the three-dimensional, time -varying volume of the flow field by obtaining simultaneous measurements of Laser Doppler Velocimetry and Particle Image Velocimetry planes is presented.
The same field is investigated with focus on the streamwise structures. Three-dimensional streamwise vortical structures are known to exist due to instabilities of plane shear layers. Similar streamwise vortices, also known as braid vortices have been observed in the past in the wake of circular cylinders with symmetric boundary conditions. The present spatio-temporal analysis demonstrated coexistence of two types of streamwise vortices in the wake, bilge and braid type of vortices. These may be due to the three dimensionality introduced by the free surface. In addition, the sufficient time resolution allowed the detection of the primary Von-Karman vortex through a plane of interrogation normal to the free stream, thus revealing the spanwise variation of the vortex shedding and its evolution at different downstream stations.
The combination of the effect of the asymmetric boundary conditions with a free surface is investigated by adding one more source of three-dimensionality in terms of inclination of the cylinder axis. Hydrogen-bubble and particle-flow visualizations are preformed in combination with Laser-Doppler Velocimetry measurements. From both qualitative and quantitative results the effects of inclination and Froude number are documented. It is proved that the vortex shedding is suppressed for high values of the Froude number, however the inclination counteracts the vortex suppression and favors the vortex shedding mechanism. In addition, in the region of the no-slip boundary condition the flow is dominated by the effect of the horseshoe vortex.
The case of a three-dimensional separated flow over a surface-mounted prism is investigated using a modified version of the system. The character of the separated from the leading edge corner shear layer and the formed separation bubble are documented in space and time along the mid-plane of symmetry of the body. Three different flows corresponding to different Reynolds numbers are studied. The unsteadiness of the flow is presented indicating a pseudo-periodic character. Large-scale, low-frequency oscillations of the shear layer that have been observed in the past using point measurement methods are now confirmed by means of a whole field velocity measurement, technique allowing a holistic view of the flow. In addition, the unsteadiness of the point of reattachment is associated with the flapping of the shear layer and the shedding of vorticity in the wake. Finally, it is demonstrated that the apparent vortex shedding mechanism of such flows is dependent on the interaction of the primary vortex of the separation bubble with a secondary vortex formed by the separation of the reverse flow boundary layer. By performing measurements with such time and space resolution the inadequacy of time averaged or point measurement methods for the treatment of such complex and unsteady flow fields becomes evident.
In final case we employ Particle-Image Velocimetry to show the effect of unsteady excitation on two-dimensional separated flow over a sharp edged airfoil. It is proved that such an approach can be used to effectively control and organize the character of the flow, potentially leading to lift increase and drug reduction of bluff bodiesPh. D.
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Bordoloi, Udeepta. "Importance-driven algorithms for scientific visualization." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1118952958.
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Ma, Wei Ping, and 馬偉平. "Flow Visualization of Axial Flow Fan." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/84316568353994939658.
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謝立德. "Flow visualization and mechanic." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/86546301367058493892.
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