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Application of Fluid-structure Interaction on Oscillating Human Vocal Folds
Meisner, Patrik ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The presented thesis is involved in the biomechanics of phonation. The aim of the thesis is to set a fluid-structure interaction between the vocal folds and air flow when the pressure from lungs reaches the physiological values. In the expected outcome the self-oscillating vocal folds should be observable with characteristics shape-shift from convergent to divergent. In theory part of the thesis is described Anatomy of the vocal tract, physiology of the human phonation, research of computational simulations, experiments and visualisation methods are described in the theory part of the thesis. In the second part, setup of computational simulation with the finite element method is presented. Besides of the fluid-structure interaction the acoustical model is set. Achieved results are presented and compared to the results in literature. Displacements are evaluated from the structural model and pressures, velocities and flow velocities are evaluated from fluid model, so as acoustics results.
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Application of Fluid-structure Interaction on Oscillating Human Vocal Folds
Meisner, Patrik ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The presented thesis is involved in the biomechanics of phonation. The aim of the thesis is to set a fluid-structure interaction between the vocal folds and air flow when the pressure from lungs reaches the physiological values. In the expected outcome the self-oscillating vocal folds should be observable with characteristics shape-shift from convergent to divergent. In theory part of the thesis is described Anatomy of the vocal tract, physiology of the human phonation, research of computational simulations, experiments and visualisation methods are described in the theory part of the thesis. In the second part, setup of computational simulation with the finite element method is presented. Besides of the fluid-structure interaction the acoustical model is set. Achieved results are presented and compared to the results in literature. Displacements are evaluated from the structural model and pressures, velocities and flow velocities are evaluated from fluid model, so as acoustics results.
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Elastic tubes in the mode of self-excited oscillation
Chlup, Hynek ; Maršík, František ; Konvičková, S.
Our paper studies experimentally the self-excited oscillations of thin-walled elastic tubes with respect to the Korotkoff sounds. The self-excited oscillation is a phenomenon, when an elastic tube looses stability of its shape and starts to oscillate, loaded only by continual flow, therefore without any external excitation. The mean flow rates, pressures at the ends of the tube, external pressures and photographs of the shape in two planes were recorded under various modes of oscillation. The effective cross-section and Young’s modulus of the tube wall were calculated by simplified formulas. The data analysis showed an increase of the oscillation frequency with a decrease of the tube wall compliance. It means the frequency of the oscillation is dependent on ratio of the wall thickness and the tube diameter. The mode of the oscillation is also influenced by the transmural pressure. The influence of the axial pretension of the tube is being studied now.
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Self-excited oscillation of the thin-walled elastic tubes
Chlup, Hynek ; Maršík, František ; Konvičková, S.
The simulation of the fluid flow through elastic pipes has many applications in a blood flow through human vessels – investigation of such phenomena as an atherosclerosis generation in artery walls, the Korotkoff's sounds generation or modeling of vascular mechanical substitutes (the so called "stents") and is therefore widely studied. Aim task is to solve the blood flow through the elastic tubes analytically, numerically and experimentally and to analyze the relation of the mechanical properties of the blood and of the vessel wall and flow instabilities, all focused on biomechanics of the cardio-vascular system. The analysis shows that frequency of self-excited oscillations increases with the decrease of arterial compliance.
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Samobuzené oscilace elastické trubice
Chlup, Hynek ; Macková, H. ; Maršík, František ; Konvičková, S.
Our paper studies experimentally the self-excited oscillations of thin-walled elastic tubes with respect to the Korotkoff sounds. The self-excited oscillation is a phenomenon, when an elastic tube looses stability of its shape and starts to oscillate, loaded only by continual flow, therefore without any external excitation. An experimental set-up was designed for the experiments. The mean flow rates, pressures at the ends of the tube and external pressures were recorded under various modes of oscillation. The effective cross-section and elastic modulus of the tube were calculated by simplified formulas. The data analysis showed an increase of the oscillation frequency with a decrease of the tube wall compliance. It means the frequency of the oscillation is dependent on ratio of the wall thickness and the tube diameter. The mode of the oscillation is also influenced by the transmural pressure.
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