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In vitro model of the cardiovascular periphery
Michálek, Martin ; Zeman, Radek (referee) ; Kohút, Jiří (advisor)
This thesis focuses on modeling of peripheral vascular network in vitro. To achieve this purpose, 2-element Windkessel model is developed. Ball valve was used to achieve resistance and compliance chamber was constructed. Ball valve and compliance chamber were then used in a mock circulatory loop with peristaltic pump. When compliance 2,18 mlmmHg was achieved and ball valve was closed according to it, real values of pulse, systolic,diastolic and mean pressure in systematic arteries were obtained. Compliance chamber altered pulse pressure and valve adjusted mean pressure. Pressure and flow waveforms were measured and input impedance was calculated and shown.
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Design modification and CFD simulation of the filling valve
Klíma, Štěpán ; Kohút, Jiří (referee) ; Klas, Roman (advisor)
This thesis deals with the design of a filling valve guide using a metal 3D printing method for application in a hydraulic press. The production of a filling valve guide using traditional forms of manufacturing in terms of labour, production, technology and time-challenging processes and the metal 3D printing method can help to overcome some of these challenges. The introduction of this paper is concerned with explaining the function of filling valves in the hydraulic press mechanism and a brief introduction to valve guide manufacturing technologies, including metal 3D printing technology. This is followed by an explanation of the new design in terms of the technology used. A strength analysis using FEA is then developed to determine the functionality of the valve guide and to optimise its shape. In this section, an iterative procedure was used to reduce the reduced stress in the ribs to 68 % of the reduced stress of the original design by changing the valve guide geometry. At the same time, a theoretical introduction to FEM is written, including an explanation of the non-linearities in FEM. This is followed by a comparison of the hydraulic losses due to oil flow through the original valve and the valve with the modified valve guide. Similar to the FEM chapter, a theoretical section is also written introducing CFD, mesh generation for CFD and turbulence models.
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Comparison of Pulsating Flow of Newtonian and non-Newtonian Fluid in Complex Geometry
Kohút, Jiří ; Rudolf, Pavel (referee) ; Jagoš, Jiří (advisor)
This master's thesis deals with pulsating flow of Newtonian and non-Newtonian fluid. Theoretical part represents necessary theoretical knowledge for pulsating flow and understanding of non-Newtonian behaviour. Furthermore the thesis focus is directed on numerical simulation of pulsating flow in straight, ideally rigid tube and in patient-specific model of human artery, more precisely in carotid. Two methods are used: numerical solution based on finite volume method (FVM) and also analytical solution using Bessel functions by Womersley. Results are validated against experimental measurements of velocity profiles by particle image velocity method (PIV). The agreement between numerical and experimental data with consideration of PIV inaccuracy was was very good from both point of views - qualitative and quantitative. Numerical solution also compare influence of turbulence and non-Newtonian behaviour towards base (laminar flow, Newtonian fluid). Developed methodology is then applied on patient-specific model of carotid, which was renovated from computed tomography. Measurements in vivo in human arteries is very expensive and often invasive. Because of that measurement outputs are limited, most of the time on pressure and flow. Computational fluid dynamics (CFD) is non-invasive and outputs are through whole domain. Due to these advantages CFD significantly contributes to understanding of hemodynamics influence in cardiovascular diseases.
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Elements reducing pressure in pipeline systems
Kohút, Jiří ; Kůrečka, Jan (referee) ; Himr, Daniel (advisor)
The aim of the bachelor thesis is to provide a comprehensive overview of control elements in piping systems. The fluid at different flow rates exhibits different behavior and due to the fluid contact with the pipeline, pressure losses occur. Elements in piping systems meet various requirements such as pressure control, flow rate control, barrier and flow direction control. The thesis deals with the categories description and functional priciples of individual elements. The practical part consists of the laboratory measurement describing characteristic of one of the pressure control elements, namely the pressure reducing valve. The measured characteristic is compared to characterstic from a company called Malgorani.
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Design of a model of the human carotid artery based on an electrohydraulic analogy
Škrlová, Nikola ; Kohút, Jiří (referee) ; Jagoš, Jiří (advisor)
The carotid artery plays a crucial role in delivering blood to the cerebral system, which ensures the proper function of the human body. Mathematical models of the cardiovascular system have been proposed to understand vascular disease. The main aim of this study is to create mathematical model of the carotid artery, using an electrohydraulic analogy. The most basic or 0D modeling of cardiovascular system includes the two-element Windkessel model. Numerical modeling was carried out in the MATLAB environment. To make the model solvable, it was necessary to determine the initial flow parameters in the common carotid. It was necessary toadjust the resulting pressure curves on the common carotid to the ideal pressure range of a healthy person. A similar process was performed for the flow in the internal carotid. Then a comparison was made with the real measured flow curve. During the verification of the law of mass conservation of the flow, a 6% deviation was discovered. This discrepancy is attributed to the process of obtaining flow values from the equations assembled in Chapter 5, as well as the rounding error inherent in MATLAB itself. This breakthrough combination of science and medicine is primarily beneficial for doctors and patients who are dealing with the disease.
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Comparison of Pulsating Flow of Newtonian and non-Newtonian Fluid in Complex Geometry
Kohút, Jiří ; Rudolf, Pavel (referee) ; Jagoš, Jiří (advisor)
This master's thesis deals with pulsating flow of Newtonian and non-Newtonian fluid. Theoretical part represents necessary theoretical knowledge for pulsating flow and understanding of non-Newtonian behaviour. Furthermore the thesis focus is directed on numerical simulation of pulsating flow in straight, ideally rigid tube and in patient-specific model of human artery, more precisely in carotid. Two methods are used: numerical solution based on finite volume method (FVM) and also analytical solution using Bessel functions by Womersley. Results are validated against experimental measurements of velocity profiles by particle image velocity method (PIV). The agreement between numerical and experimental data with consideration of PIV inaccuracy was was very good from both point of views - qualitative and quantitative. Numerical solution also compare influence of turbulence and non-Newtonian behaviour towards base (laminar flow, Newtonian fluid). Developed methodology is then applied on patient-specific model of carotid, which was renovated from computed tomography. Measurements in vivo in human arteries is very expensive and often invasive. Because of that measurement outputs are limited, most of the time on pressure and flow. Computational fluid dynamics (CFD) is non-invasive and outputs are through whole domain. Due to these advantages CFD significantly contributes to understanding of hemodynamics influence in cardiovascular diseases.
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Elements reducing pressure in pipeline systems
Kohút, Jiří ; Kůrečka, Jan (referee) ; Himr, Daniel (advisor)
The aim of the bachelor thesis is to provide a comprehensive overview of control elements in piping systems. The fluid at different flow rates exhibits different behavior and due to the fluid contact with the pipeline, pressure losses occur. Elements in piping systems meet various requirements such as pressure control, flow rate control, barrier and flow direction control. The thesis deals with the categories description and functional priciples of individual elements. The practical part consists of the laboratory measurement describing characteristic of one of the pressure control elements, namely the pressure reducing valve. The measured characteristic is compared to characterstic from a company called Malgorani.
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