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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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Interesting cases of fluid mechanics
Čáp, Filip ; Hájek, Ondřej (referee) ; Jedelský, Jan (advisor)
This bachelor thesis deals with the description of some interesting phenomena in the field of fluid mechanics, methods of flow visualization and its recording using a high-speed camera. First, a number of terms and different types of fluid flow are briefly introduced, which is followed by the description of the methods of visualization that enhance the visibility of flow of liquids and gases. The thesis also describes high-speed cameras and examines some interesting effects in fluid dynamics which can be encountered in everyday life as well as in engineering practice. The last chapter is then dedicated to the conducted experiments and their recordings.
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Segner wheel
Jahn, Jan ; Hudec, Martin (referee) ; Fic, Miloslav (advisor)
This bachelor thesis focuses on description of water turbine called the Segner wheel, which is considered as a precursor of modern water turbines. Segner’s contribution is to demonstrate an opportunity of dynamic force exerted by fluid jet. There is some historical information about his life and additional adaptations of the original invention. Wheel function analysis is based on laws of hydrostatics and hydrodynamics. The Segner wheel model is a part of this thesis. Last chapter discuses applications of the Segner wheel up to the present day.
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Interesting cases of fluid mechanics
Čáp, Filip ; Hájek, Ondřej (referee) ; Jedelský, Jan (advisor)
This bachelor thesis deals with the description of some interesting phenomena in the field of fluid mechanics, methods of flow visualization and its recording using a high-speed camera. First, a number of terms and different types of fluid flow are briefly introduced, which is followed by the description of the methods of visualization that enhance the visibility of flow of liquids and gases. The thesis also describes high-speed cameras and examines some interesting effects in fluid dynamics which can be encountered in everyday life as well as in engineering practice. The last chapter is then dedicated to the conducted experiments and their recordings.
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Mathematical modelling of selected problems in cryogenic fluid mechanics
Hodic, Jan ; La Mantia, Marco (advisor) ; Kreml, Ondřej (referee)
The dynamics of low-temperature fluids, such as superfluid helium 4, is an open scientific problem. The experimental study of similarities and differences between quantum (superfluid) and classical (viscous) flows is specifically an active research field, which already led to significant progress in our phenomenological understanding of the underlying physics. It also revealed that a comprehensive theoretical description is still missing, as, for example, in the case of the observed behaviour of moving bodies in quantum flows. The work aim is to derive the existence theory for the weak ort he strong solution of a relevant system of equations based on the Landau model of superfluid helium 4 and appropriate properties of the solution.
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Mathematical modelling of selected problems in cryogenic fluid mechanics
Hodic, Jan ; La Mantia, Marco (advisor) ; Schmoranzer, David (referee)
The dynamics of low-temperature fluids, such as superfluid helium 4, is an open scientific problem. The experimental study of similarities and differences between quantum (superfluid) and classical (viscous) flows is specifically an active research field, which already led to significant progress in our phenomenological understanding of the underlying physics. It also revealed that a comprehensive theoretical description is still missing, as, for example, in the case of the observed behaviour of moving bodies in quantum flows. The work aim is to derive the existence theory for the weak solution of a relevant system of equations based on the Landau model of superfluid helium 4 and appropriate numerical schemes to solve these equations.
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Visualization of particle motions in superfluid helium flows
Švančara, Patrik ; La Mantia, Marco (advisor)
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 particle motions in superfluid helium flows
Švančara, Patrik ; La Mantia, Marco (advisor)
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 superfluid helium flows in the proximity of boundaries
Hrubcová, Petra ; La Mantia, Marco (advisor) ; Jackson, Martin James (referee)
The investigation of superfluid helium (He II) flows is an active and challenging research field. Progress in our phenomenological understanding of the underlying physics has been achieved in recent years by employing flow visualization techniques that allow following the motion of relatively small particles suspended in the fluid. The flow-induced particle behaviour is studied in the case of thermal counterflow - the most common type of He II flow - close to the flow source, where a significant vorticity enhancement is observed. The work aim is therefore to give a significant contribution to the emerging line of scientific enquiry dedicated to the study of wall-bounded quantum flows.
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