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Studies on Non-Newtonian Behavior in Slit-flow rheometer at Unsteady flow
Halama, Lukáš ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
The thesis deals with the description of the unstable flow of non-Newtonian fluid in a slit-flow rheometer, which negatively affects its behaviour. The initiators of unstable fluid flow are the roughness of the rheometer slit walls, the slip on the rheometer walls, and the influence of the inlet and outlet region geometry of the rheometer slit. The work contains methodical procedures for mathematical consideration of individual unstable fluid flow initiators and design of change of slit geometry of slit-flow rheometer. Part of the work is also a comparison of the most commonly used rheological models, derivation of general relations for the creation of the velocity profile of individual rheological models and their subsequent implementation in the rheological application, which significantly simplifies the process of evaluation of measured data when measured on slit-flow rheometer. This application can be used to determine basic parameters in CFD simulations or as a teaching aid.
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Effect of lubricant rheology on lubrication film thickness.
Prášilová, Alena ; Šperka, Petr (referee) ; Křupka, Ivan (advisor)
Lubrication is a very important part of mechanical engineering, which ensures high lifetime of machine parts, reduction of friction and wear and also it leads to decreasing of power consumption. In this bachelor`s thesis there is described rheology of newtonian and non-newtonian lubricants and its effect on lubrication film thickness. Measured central film thickness values are compared with theoretical prediction.
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The flow of magnetic liquid with Bingham model application
Stejskal, Jan ; Krausová, Hana (referee) ; Haluza, Miloslav (advisor)
Main topic of this thesis are magnetic fluids. These are specific type of fluids which can simplistically be considered as Bingham fluids. Main issues regarding the magnetic fluids mentioned in this thesis are: rheological properties of the magnetic fluids, behaviour of the magnetic fluids and the use of the magnetic fluids in industrial applications. Main goal is to apply Binghams model on the the magnetic fluids assuming that this model can be applied with a good accuracy. Equations which describe behaviour of the Bingham fluids are constructed. Some assumptions which have to be respected to use this analytical equations for magnetic fluids are formulated. Flow of bingham fluid is analytically solved in some simplificated cases with consideration of laminar flow. Analytical results are confronted with numerical ones obtained from CFD software Fluent for the purpose of verification.
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Non-newtonian liquids flow
Mašán, Roman ; Klas, Roman (referee) ; Himr, Daniel (advisor)
The bachelor's thesis explores the topic of Non-Newtonian fluids, which behave unusually compared to Newtonian fluids. It characterizes their rheology, clarifies the reasons and mechanisms responsible for their non-standard properties. The thesis also includes a mathematical description of modeling these fluids, which is subsequently applied to elucidate the nature of flow and phenomena occurring in laminar and turbulent regimes.
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The interaction of non-newtonian fluids with a flexible wall
Šedivý, Dominik ; Drábková, Sylva (referee) ; Šidlof,, Petr (referee) ; Fialová, Simona (advisor)
The doctoral thesis deals with an interaction between non-newtonian fluid and flexible wall. This interaction occurs continuously in all human bodies since a blood is a non-newtonian fluid and blood vessels belong to hyperelastic materials. The main aim of the thesis was to study and evaluate the impact of non-newtonian fluid on the flow. The aorta is blood vessel with the highest deformations and flowrates and it was studied in this work. The practical section of thesis is divided into two parts. Experimental measurements are contained in the first part and numerical simulations are in the second part. A new testing device was designed and built. Measurements were done for both types of fluid (newtonian and non-newtonian) and with two types of tubes. One of them was made from glass and was considered as rigid. The second one was pliable and it was made from silicon. Measurement outputs were velocity profiles (measured by PIV), pliable tube deformations and absolute pressures at the inlet and the outlet of the tubes. Simulations were based on experimental data and were performed in software ANSYS. The simulation of the flow in the pipe with rigid wall was calculated with computational fluid dynamic. Fluid-structure interaction was applied in case of pliable tube, therefor structural solver was coupled with CFD solver. Simulations were used for evaluation of physical quantitie which were not possible to measure. Simple mathematical model was created based on the results.
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Note on the problem of compressible non-Newtonian fluids
Caggio, M. ; Nečasová, Šárka
The aim of the paper is to consider the compressible non-Newtonian fluids of power law type when the viscosity coeffcients depend not only on invariants of velocity field but also on the density. We introduce approximation scheme using model of multipolar fluids. After then passing with higher viscosity to zero we get the measure valued solution of the problem.
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Studies on Non-Newtonian Behavior in Slit-flow rheometer at Unsteady flow
Halama, Lukáš ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
The thesis deals with the description of the unstable flow of non-Newtonian fluid in a slit-flow rheometer, which negatively affects its behaviour. The initiators of unstable fluid flow are the roughness of the rheometer slit walls, the slip on the rheometer walls, and the influence of the inlet and outlet region geometry of the rheometer slit. The work contains methodical procedures for mathematical consideration of individual unstable fluid flow initiators and design of change of slit geometry of slit-flow rheometer. Part of the work is also a comparison of the most commonly used rheological models, derivation of general relations for the creation of the velocity profile of individual rheological models and their subsequent implementation in the rheological application, which significantly simplifies the process of evaluation of measured data when measured on slit-flow rheometer. This application can be used to determine basic parameters in CFD simulations or as a teaching aid.
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The flow of magnetic liquid with Bingham model application
Stejskal, Jan ; Krausová, Hana (referee) ; Haluza, Miloslav (advisor)
Main topic of this thesis are magnetic fluids. These are specific type of fluids which can simplistically be considered as Bingham fluids. Main issues regarding the magnetic fluids mentioned in this thesis are: rheological properties of the magnetic fluids, behaviour of the magnetic fluids and the use of the magnetic fluids in industrial applications. Main goal is to apply Binghams model on the the magnetic fluids assuming that this model can be applied with a good accuracy. Equations which describe behaviour of the Bingham fluids are constructed. Some assumptions which have to be respected to use this analytical equations for magnetic fluids are formulated. Flow of bingham fluid is analytically solved in some simplificated cases with consideration of laminar flow. Analytical results are confronted with numerical ones obtained from CFD software Fluent for the purpose of verification.
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