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Computational modelling of blood flow in the carotid artery with serial stenosis
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The aim of this bachelor's thesis is to analyse the effect of double stenosis on flow and stress characteristics in the carotid artery. First, based on the stated literature, a literature search is conducted regarding blood flow in the arterial system. Then, the procedure of creating idealized models of an artery with double stenosis and the procedure of mesh creation and numerical solution are described. The models have different size of the stenosis and different distance between stenosis. In the final stage, the results are analysed first for stationary flow, then one model is selected on which is performed the analysis for pulsating flow. Analytical calculation of pressure drop and comparison with numerical calculation is also part of this work.
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Computational modeling of the interaction of flowing blood with the artery tube with the atheroma
Freiwald, Michal ; Jagoš, Jiří (referee) ; Švancara, Pavel (advisor)
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
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Overview to arterial stents and possibilities of their computational modelling
Ondříšková, Tereza ; Lisický, Ondřej (referee) ; Turčanová, Michaela (advisor)
This bachelor thesis deals with arterial stents and possibilities of their computational modelling. The thesis contains a medical minimum, which is necessary to understand the principle of arterial stents. Furthermore, the thesis is focused on methods of a stent implantation, materials used for manufacturing and covering and the most used designs. There is a research study of analytical and numerical computational modelling of them with emphasis on the finite element method. In the last part of this thesis there was performed an analytical calculation of stress appeared in the carotid artery wall after stent implantation using a simplified model of stent-artery configuration. Then these stress functions were plotted and evaluated.
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Modelling of blood flow in a carotid artery with stenoses
Štefek, Martin ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This bachelor's thesis deals with the analysis of blood flow in a carotid artery with stenoses in the area of the bifurcation. The current state of knowledge is presented in the theoretical part. As part of the practical part of the work, several 2D models of the artery with stenoses of dif-ferent sizes and distances were created. An ideal mesh of finite volumes was created and select-ed. Using the ANSYS Fluent program, basic hemodynamic parameters such as flow velocity, wall shear stress, pressure and fractional flow reserve (FFR) were evaluated for stationary flow. A time step was determined for the transient flow, and then the flow speed and shear stress on the walls at points were evaluated as a function of time.
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Computational modelling of the influence of stenoses on blood flow in the carotid artery
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This diploma thesis deals with blood flow in carotid artery with tandem double stenosis. In the first part there is described cardiovascular system with emphasis on blood and arteries. In the practical part, geometric models of the carotid artery with 30% and 70% stenosis, as well as a model without stenosis, are created. The second stenosis is not included in the model of geometry but modeled using Windkessel effect. Blood is modeled as a non-Newtonian fluid using the Carreau model. After the calculations, the blood flow and arterial wall stress are evaluated, and the results are compared among the different geometry models. Critical values of shear stress, TAWSS, OSI, and FFR, as well as the mass flow rate in the internal carotid artery, are assessed.
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Impact of residual stresses and uncoiling of arterial specimen on its mechanical response
Sochor, Ondřej ; Lisický, Ondřej (referee) ; Burša, Jiří (advisor)
This thesis examines the impact of residual stresses in the carotid artery wall and the influence of specimen uncoiling on its mechanical response. The introductory part provides basic knowledge about the anatomy and the pathology of blood vessels, as well as overview of common methods used for testing artery samples. The main body of the thesis is divided into two sections. The first section focuses on the impact of specimen uncoiling on its mechanical response during the equibiaxial tensile test. It begins by describing the method used for sample testing and the method used for obtaining material constants from the mechanical response. These constants are then used as input for FEM simulation of the uncoiling and subsequent equibiaxial tensile test simulation on idealized model of geometry. The mechanical behaviour of the uncoiled model is compared to behaviour of the stress-free planar model to determine the influence of uncoiling. In the second section, the influence of residual stresses in the artery wall on its mechanical response is explored. This section includes a description of two methods used to show residual stress release, which are then used for specimen testing. The experiments are used to evaluate input parameters per layer for the model of geometry and subsequent FEM analysis. By comparing results from three levels of modeling, the impact of residual stresses on the artery’s mechanical response is determined.
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Computational modeling of the interaction of flowing blood with the artery tube with the atheroma
Freiwald, Michal ; Jagoš, Jiří (referee) ; Švancara, Pavel (advisor)
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
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Overview to arterial stents and possibilities of their computational modelling
Ondříšková, Tereza ; Lisický, Ondřej (referee) ; Turčanová, Michaela (advisor)
This bachelor thesis deals with arterial stents and possibilities of their computational modelling. The thesis contains a medical minimum, which is necessary to understand the principle of arterial stents. Furthermore, the thesis is focused on methods of a stent implantation, materials used for manufacturing and covering and the most used designs. There is a research study of analytical and numerical computational modelling of them with emphasis on the finite element method. In the last part of this thesis there was performed an analytical calculation of stress appeared in the carotid artery wall after stent implantation using a simplified model of stent-artery configuration. Then these stress functions were plotted and evaluated.
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|
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Computational modelling of blood flow in the carotid artery with serial stenosis
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The aim of this bachelor's thesis is to analyse the effect of double stenosis on flow and stress characteristics in the carotid artery. First, based on the stated literature, a literature search is conducted regarding blood flow in the arterial system. Then, the procedure of creating idealized models of an artery with double stenosis and the procedure of mesh creation and numerical solution are described. The models have different size of the stenosis and different distance between stenosis. In the final stage, the results are analysed first for stationary flow, then one model is selected on which is performed the analysis for pulsating flow. Analytical calculation of pressure drop and comparison with numerical calculation is also part of this work.
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