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Hydrodynamic mixing of water-ask mixture in vessel
Holub, Přemysl ; Franc, Zdeněk (referee) ; Habán, Vladimír (advisor)
Master´s thesis Hydrodynamic mixing of water-ash mixture in vessel is interested in describing fluid and solid particles flow in a vessel. The mixing was conducted in cylindrical vessel by a radial nozzle. The goal of the thesis is to describe flow field and places where the most of the particles are descending according to position, depth, flow rate and nozzle orientation in the vessel. An experiment was conducted in order to investigate and document 8 different positions and orientation of the nozzle. Significant changes in flow fields and mixing time were observed. A mathematical model of the vessel with the nozzle was created in Fluent program. Places with the lowest velocities according to the model were in good agreement with places where the most of the solid particles were descending.
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Boundary Vorticity Element Method for 2D Fluid Flow
Fic, Miloslav ; Pochylý, František (referee) ; Štigler, Jaroslav (advisor)
This master’s thesis deals with boundary vorticity element method for 2D fluid flow. The aim of this work is to program this method with continuous vorticity lay-out and to validate method with various boundary conditions. The computed results are presented in this work. Advantages and disadvantages of each one boundary condition are pointed out. New one boundary condition for boundary vorticity element method is applied in this thesis.
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Thermodynamic modeling of rolling fluid turbine
Kincl, Ondřej ; Pavelka, Michal (advisor) ; Hron, Jaroslav (referee)
in English Ondřej Kincl 21 May 2020 Rolling turbine is a small hydraulic turbine invented by Doc. Ing. Miroslav Sedláček CSc. in 1998. This turbine is bladeless, exhibits various interesting behaviour and operates on the basis of a yet unknown hydraulic principle. This thesis attempts to find an explanation using incompressible Navier- Stokes equations. We will introduce the concept of drag inversion - the idea that fluid force in rolling turbines is a positive feedback to the motion itself. This is explained in a simplified model using analytical methods. These results are then verified in a numerical simulation.
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Impact of Turbulence Generators on Turbulent Characteristics and Structures
Kellnerová, Radka ; Jurčáková, Klára ; Jaňour, Zbyněk
The turbulent generators are routinely used to produce very turbulent flows. Special type of vertically slenderize spires are applied to enhance turbulent diffusion from the surface upwards in order to increase the boundary layer depth. This paper studies the influence of variable upstream distance of generators on formation of both vortical and non-vortical organized structures within a test section. The 2-component 2-dimensional time-resolved particle image velocimetry measurement of the flow was performed in the wind channel with very rough surface. Intermittent flow dynamics was evaluated by means of higher order moments, vorticity, quadrant and wavelet analysis. The downstream evolution of the flow suggests that equilibrium between roughness- and spires-produced turbulence was reached at the distance of 7 spires height.\n
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Tornadoes in the Czech Republic
Šáfrová, Martina ; Zacharov, Petr (advisor) ; Bližňák, Vojtěch (referee)
The Bachelor work is devoted to the task of occurance the tornado over our territory. The goal of the work is on the basis of available czech and foreing literature to make acquaintance with the pesent physique knowledge of organised convection rise and tornado formation. The second goal was to show overview of tornado rise during the last ten years and introduct several tornado rise studyings. There were calculated precursors of strong convection for these rise studyings and there values were discussed in the work. Key words: tornado, convection, precursors of convection, vorticity
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Modelling of exoplanetary atmospheric circulation
Novák, Jiří ; Brechler, Josef (advisor) ; Halenka, Tomáš (referee)
In this thesis we study the properties of exoplanetary atmospheres. The first part describes methods for searching exoplanets, statistics of discovered exoplanets and the sampling factors. The second part describes the properties of chosen planets and moons in the Solar system (Venus, Mars and Titan) and also possible properties of the exoplanetary atmospheres that are only briefly understood. The third part describes the atmospheric models which incorporate a full 3D model of the atmosphere, and a shallow- water model. We also show the results of exoplanetary atmospheric models published in the scientific journals. This part also describes the icosahedral geodetic grid that is advantageous for the global climatic models, and also discretisation on sphere and the application of the operators (gradient, divergence, vorticity) on geodetic grid. The last part is about creating program for global shallow water model in divergence-vorticity variables with forcing system with using icosahedral geodetic grid - we describe technical properties connected with model creating, parameters which the model uses during time integration, geographic system for results display and we show results for various kinds of extrasolar planets and planets in the Solar system. We used several numerical tests for testing model...
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On stability of 2D flow-field
Uruba, Václav
Stability of a 2D flow-field generated under 2D boundary conditions will be analyzed using various methods. The most practical cases of such flows are found to be highly instable and thus unphysical. The presented paper analyses the situation with help of experiments and mathematical modelling from literature defining an interesting areas for future experimental research, which could extend the published experimental studies and/or verify some recent results of mathematical modelling.
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Boundary Vorticity Element Method for 2D Fluid Flow
Fic, Miloslav ; Pochylý, František (referee) ; Štigler, Jaroslav (advisor)
This master’s thesis deals with boundary vorticity element method for 2D fluid flow. The aim of this work is to program this method with continuous vorticity lay-out and to validate method with various boundary conditions. The computed results are presented in this work. Advantages and disadvantages of each one boundary condition are pointed out. New one boundary condition for boundary vorticity element method is applied in this thesis.
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Hydrodynamic mixing of water-ask mixture in vessel
Holub, Přemysl ; Franc, Zdeněk (referee) ; Habán, Vladimír (advisor)
Master´s thesis Hydrodynamic mixing of water-ash mixture in vessel is interested in describing fluid and solid particles flow in a vessel. The mixing was conducted in cylindrical vessel by a radial nozzle. The goal of the thesis is to describe flow field and places where the most of the particles are descending according to position, depth, flow rate and nozzle orientation in the vessel. An experiment was conducted in order to investigate and document 8 different positions and orientation of the nozzle. Significant changes in flow fields and mixing time were observed. A mathematical model of the vessel with the nozzle was created in Fluent program. Places with the lowest velocities according to the model were in good agreement with places where the most of the solid particles were descending.
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