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Visualization of particle motions in superfluid helium flows
Švančara, Patrik ; La Mantia, Marco (advisor) ; Chagovets, Tim (referee)
Flows of normal and superfluid 4 He (He I and He II, respectively) are investigated experimentally. Relatively small particles of solid hydrogen and deuterium are suspended in the experimental volume and their motions are tracked in both mechanically and thermally driven flows. A statistical study of the particle velocity and velocity increment distributions is performed at scales smaller and larger than the mean distance between quantized vortices, the quantum length scale of the investigated flows. We show that, at small scales, the observed particle dynamics in He II is greatly influenced by that of quantized vortices. We, additionally, report that this behavior is independent of the imposed large-scale flow. Instead, at large scales, we observe that particle motions are quasiclassical, that is, very similar to those reported to occur in turbulent flows of viscous fluids. The study reinforces therefore the idea of close similarity between viscous flows and large-scale (mechanically-driven) flows of He II, and simultaneously highlights the small-scale differences due to the presence of quantized vortices in He II.
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Visualization of computed flows using particle tracing methods
Miloš, Vojtěch ; Hron, Jaroslav (advisor) ; Kučera, Václav (referee)
A mesh of tetrahedrons is build from a real data that were obtained by CT (computer tomography) or MRI (magnetic resonance imaging) scan of a blood vessel and then velocity vectors are computed in every vertex using the nite element method. The objective of the work is to design and implement a particle tracing algorithm in such a mesh with an emphasis on a maximum accuracy of the result. For this purpose, an analytic integration method is presented, which can be used thanks to piecewise linear vector eld. We propose our own modi cation of this method and compare its results with the conventional numerical integration. Furthermore, the work describes modi cations of common step methods that are used to determine the cell that contains a particular particle without the need to search the whole mesh in each step. Powered by TCPDF (www.tcpdf.org)
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Modern flow visualization techniques
Pištěcká, Kateřina ; Koutník, Tomáš (referee) ; Popela, Robert (advisor)
The subject of this bachelor thesis is an overview of the flow visualization methods applied in the wind tunnels and fly tests. An overview of flow visualization methods is presented in the first part of the work. The particular methods are presented and evaluated with respect of its complexity, requirements on the instrumentation and expanses. The pros and cons are mentioned for each method finally. The second part of the work deals with selection of the flow visualization method suitable for application in the wind tunnel of the Aeronautical department of the VUT Brno.
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Vizualization of liquid break-up from atomization nozzles
Janáčková, Lada ; Bělka, Miloslav (referee) ; Jedelský, Jan (advisor)
V oblasti mechaniky tekutin hraje vizualizace významnou roli. Fotografie poskytují vhled do zásad chování tekutin a obecně pomáhají k lepšímu pochopení fyzikálních procesů proudění. Tato práce se zabývá vizualizací rozpadu kapalin u rozprašovacích trysek. Práce popisuje základy rozpadu kapalin, stejně jako metody pro vizualizaci. Dále je v práci probrána a experimentálně testována analýza prvků ve vizualizačních metodách. Laboratorní testy byly provedeny na malé tlakové vířivé trysce určené pro spalování kerosinu v proudovém leteckém motoru a část experimentů byla provedena na tlakové spirálové trysce. Práce dokumentuje vliv zdroje světla na kvalitu fotografie. Chování spreje je navíc analyzováno pomocí makrofotografie se zaměřením na primární rozpad, který hraje hlavní roli v celém procesu tvorby spreje a sprejových charakteristik.
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Testing of ventilation outlets for a passenger car cabin
Dohnal, Martin ; Zaremba, Matouš (referee) ; Jedelský, Jan (advisor)
This thesis deals with experimental testing of car cabin ventilation outlets. In first part the main characteristics of air flowing are made and applied on stream from outlet. Next part deals with function and impact of car cabin ventilation system. Another part is dedicated to overview of commonly used metod of outlet testing. Research of usage of different type of outlets in mid-class cars was made. The main part of this thesis is done in final part where the testing is described by the smoke visualisation with use of laser knife and evaluation of results is performed.
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Evaluation of functionality of ventilation outlet in passenger car cabin
Caletka, Petr ; Kamenský, Petr (referee) ; Jedelský, Jan (advisor)
This work engages in flow boundaries detection that flows from a car ventilation outlet. Smoke visualization was chosen for the flow visibility. There were applied three detection methods on the pictures with different types of quality. It was evaluated a suitability of these detection methods for the pictures with different types of quality. This suitability was evaluated based on the detected shapes of the flow and obviously based on the detected direction angles.
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Application of HS camera to problems of fluid mechanics
Bolcek, Adam ; Elcner, Jakub (referee) ; Jedelský, Jan (advisor)
The main subject of this bachelor thesis is visualization of liquids and gases and their recor-ding with the help of a high-speed camera. The first part deals with types of the high-speed cameras. Also, it is concerned with the description of the Olympus i-SPEED 2 camera which was used for the experiment. Finally, the thesis investigates fundamental parameters of the high-speed cameras and their influence on the recording. The second part describes different methods of visualisation of liquids and gases and also consequent advantages and disadvantages of using each particular method. The last part is dedicated to the creation of my own recording of the visualisation of flowing of gas and its analysis and also to the finding of an optimal setting of the camera and of the lighting of the scene of the recording.
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Flow visualization
Vavrla, Zdenek ; Šperka, Oldřich (referee) ; Rudolf, Pavel (advisor)
This bachelor´s thesis deals with fluid flow visualization methods in the air and water. First brief characteristic of the basic concepts of fluid flow is described, such as streamline, laminar and turbulent flow. The described visualization methods are divided into certain types and are used for fluid or gas. These methods provide a qualitative view of the flow and create the overview of the characteristics of gas or liquid flow. Some of these methods are simple and some are more complex. Finally, a simple experiment of liquids flow visualization is described by very powerful laser pointer.
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Flow visualization methods
Ďurdina, Lukáš ; Jedelský, Jan (referee) ; Lízal, František (advisor)
ĎURDINA, L. Flow visualization methods. Brno: Brno University of Technology, Faculty of Mechanical Engineering, 2010. 45 p. Thesis supervisor Ing. František Lízal. This thesis deals with fluid flow visualization methods with respect to their practical application possibilities. Chronological description of the historically valuable visualization experiments emphasises the role of visualization in the experimental fluid mechanics. A brief characteristic of the flow field contains mathematical description of the objects, which can be visualized. Visualization methods are divided into experimental and computer aided methods. Individual methods are ordered subsequently beginning with those with lowest requirements for equipment to the more sophisticated methods. Various techniques, which provide qualitative and quantitative description of the tested gas or liquid flow, are described. The overview for the choice of methods for various applications sums up the important facts from previous chapters. Description of a simple helium bubble flow visualization experiment realized in a lab can be found at the end of the thesis.
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