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Fluid-structure interaction between blood and dissipating artery wall
Fara, Jakub ; Tůma, Karel (advisor) ; Bodnár, Tomáš (referee)
In this thesis we introduce a new fluid-structure interaction model in the Eulerian description. This model is developed for blood flow in viscoelastic artery. For the fluid part a non-Newtonian model Oldroyd-B is used and for the structure part Kelvin-Voigt model is employed. Kelvin-Voigt model will be reached by a limiting process of the Oldroyd-B model. Interface between these two materials is guaranteed by conservative level-set method. Numerical tests of this model is performed by finite element method. This model is used for a simulation of two problems: a two dimensional channel with viscoelastic walls and pulsating inflow and Turek-Hron FSI benchmark. 1
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When can a contract constitute the relation of influence or control and their potential consequences?
Bodnar, Tomáš ; Čech, Petr (advisor) ; Černá, Stanislava (referee)
When can a contract constitute the relation of influence or control and their potential consequences? The aim of my thesis is the description of the regulation of group entities (with the exception of concern law) with emphasis on the possibility to establish such relationship by a contract. I am trying to prove that establishment of the relationship of influence and control is possible. I am further trying to prove that such situations are not common in practice. Controlling relationship established by a contract is even quite unique. Another aim of my thesis is to describe the legal consequences of group entities under the Act on Corporations, especially the compensation for damages. However I would also like to take into consideration other consequences of group entities within the Act on corporations.
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On the influence of diffusion stabilization in Oldroyd-B fluid flow simulations
Pires, M. ; Bodnár, Tomáš
This work presents some numerical tests of finite element solution of incompressible Oldroyd-B fluid flows. The effect of numerical stabilization using artificial stress diffusion is investigated in detail. The limits of Weissenberg number We for which it is possible to obtain the numerical solution were studied depending on the Reynolds number Re and the diffusion parameter. Series of numerical tests were performed for steady two-dimensional Oldroyd-B fluid flow in corrugated channel (tube). The numerical results clearly proved the advantage (higher attainable We) of stabilized numerical method over the classical formulation without the artificial stress diffusion.
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Fluid-structure interaction between blood and dissipating artery wall
Fara, Jakub ; Tůma, Karel (advisor) ; Bodnár, Tomáš (referee)
In this thesis we introduce a new fluid-structure interaction model in the Eulerian description. This model is developed for blood flow in viscoelastic artery. For the fluid part a non-Newtonian model Oldroyd-B is used and for the structure part Kelvin-Voigt model is employed. Kelvin-Voigt model will be reached by a limiting process of the Oldroyd-B model. Interface between these two materials is guaranteed by conservative level-set method. Numerical tests of this model is performed by finite element method. This model is used for a simulation of two problems: a two dimensional channel with viscoelastic walls and pulsating inflow and Turek-Hron FSI benchmark. 1
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Mathematical modeling of blood coagulation process
Čapek, Marek ; Hron, Jaroslav (advisor) ; Bodnár, Tomáš (referee) ; Lukáčová Medvídová, Mária (referee)
On vessel wall injury the complex process of blood coagulation is set off. It is composed of vasoconstriction, primary hemostasis, secondary hemostasis and fibrinolysis. This work enriches current model of primary hemostasis of Storti. The previous model used ALE formalism for tracing of development of platelet plug. The phase field method is used for tracing of the development of interface blood-thrombus. Storti's primary hemostasis was extended to capture the fact, that the platelets can be activated in the blood flow in the area of reactive surface not only by influence of chemical agents like thromboxane, ADP and thrombin but also by their exposure to elevated values of shear stress. In our first approach we deal the emerging thrombus as a fluid with very high viscosity. In the second approach it was assumed, that platelet plug develops as a viscoelastic material according to constitutive equations of clot introduced by Kempen. In this manner platelet clot matures into blood clot. In both approaches the blood is represented as a non-Newtonian fluid. The framework of the phase field method was applied also to the model of high shear rate thrombosis of Weller. Weller's original model of Weller took advantage of the cylindrical symmetry of computational domains for its computations, hence the...
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Numerical tests of far-field boundary conditions for stably stratified flows
Bodnár, Tomáš ; Fraunié, P. ; Řezníček, Hynek
This numerical study presents the results of simulations of stably stratified wall-bounded flows. The effect of artificial far-field boundary conditions is studied in detail. The standard homogeneous Neumann condition for pressure is replaced by a non-homogeneous condition depending on local velocity and its gradient. The two-dimensional tests are performed for the case of flow over a low isolated hill. The simulations on computational domains with three different heights are discussed to evaluate the performance of the new far-field artifcial boundary condition. The model is based on Boussinesq approximation of non-homogeneous Navier-Stokes equations, solved using artificial compressibility method, looking for a steady solution.
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