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Large Eddy Simulation of Turbulent Two-Phase Flow
Volavý, Jaroslav ; Fürst, Jiří (referee) ; Vimmr, Jan (referee) ; Jícha, Miroslav (advisor)
Doctoral thesis deals with the numerical simulations of two-phase flows, especially with prediction of movement of dispersed phase (particles) carried by fluid. The Euler-Lagrange approach was applied for description of the system fluid-particles. It means that the fluid is considered to be continuum and its movement is described using Euler approach. Particles are regarded as mass points and their movement is solved using Lagrangian approach. The Large Eddy Simulation method was adopted for solution of the fluid flow. The series of simulations of the backward-facing step flow laden with particles were performed. The concentration of the particles in the flow was high enough for consideration of the influence of particles on the turbulence of the carrier phase. The developed scheme for generation of turbulence on the inlet is applied. The influence of anisotropic decomposition of subgrid energy on movement of particles was studied in the frame of this work.
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Investigation of Transonic Flow through Linear Cascade with Single Blade Incidence Angle Offset
Fürst, J. ; Musil, Josef ; Šimurda, David
The contribution deals with numerical and experimental investigation of the effect of incidence angle offset in a two-dimensional section of a flat linear blade cascade in a high-speed wind tunnel. The aim of the work is to complement ongoing research of quasi-stationary approximation of aerodynamic flutter by examination of setups leading to transonic flow regimes. The numerical simulations were realized by finite-volume, in-house code developed on top of the open-source software package OpenFOAM. The experiments were conducted in correspondence with the setting of numerical simulations. The comparison of experimental and numerical data is presented on the isentropic Mach number distributions at various locations in the blade cascade. The description of transonic flow structures in the vicinity of blades is also provided.
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Travel Times Visualization Based on Public Transport Timetable
Fürst, Jan ; Pilát, Martin (advisor) ; Fink, Jiří (referee)
People often use public transport to travel to places they visit on regular basis. For these people, it would be very useful if they could live in a place, from which they could get faster to all the places they visit. The problem is how to find such a place. This problem is what we are trying to solve in our web application. By generalizing the standard public transport search we make it possible to calculate the travel times from user-defined places to all other reachable places. We visualize calculated travel times in an interactive map to simplify the search for the suitable place with the lowest travel times. Our web application uses our internal library which contains the functionality required for travel time calculations. This library could be used independently on the web application to solve other problems that require evaluation of travel times by public transport. 1
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Computer simulation and numerical analysis of compressible flow problems
Kubera, Petr ; Felcman, Jiří (advisor) ; Knobloch, Petr (referee) ; Fürst, Jiří (referee)
The thesis deals with the construction of an adaptive 1D and 2D mesh in the framework of the cell- centered finite volume scheme. The adaptive strategy is applied to the numerical solution of problems governed by the Euler equations, which is a hyperbolic system of PDE's. The used algorithm is applicable to nonstationary problems and consists of three independent parts, which are cyclically repeated. These steps are PDE evolution, then mesh adaptation and recovery of numerical solution from the old mesh to the newly adapted mesh. Owing to this the algorithm can be used also for other hyperbolic systems. The thesis is focused on the development of our mesh adaptation strategy, based on the anisotropic mesh adaptation, which preserves the geometric mass conservation law in each computational step. The proposed method is suitable to solve problems with moving discontinuities. Several test problems with moving discontinuity are computed to compare our algorithm with Moving Mesh algorithms.
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Mathematical modelling of air-flow in geometrically complicated areas
Fuka, Vladimír ; Brechler, Josef (advisor) ; Fürst, Jiří (referee) ; Jaňour, Zbyněk (referee)
The Charles University Large-eddy Microscale Model (CLMM) and its application are presented. It is a numerical model for simulation of turbulent flow and dispersion in the planetary boundary layer. CLMM solves the incompressible Navier-Stokes equations in the Boussinesq approximation and describes turbulence using the large eddy simulation. Three applications of the model are presented. In the first case, the model is applied to the stable boundary layer over a flat terrain. The second case presents the simulations of stably stratified flows over obstacles. The last case deals with the dispersion of a hazardous material within an urban canopy. It was performed in the frame of the COST Action ES1006 and uses the Michelstadt flow and dispersion dataset for model validation.
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Effect of Various Boundary Conditions on the Supersonic Flow Through the Tip-Section Turbine Blade Cascade with a Flat Profile
Musil, Josef ; Příhoda, Jaromír ; Fürst, J.
The paper deals with the numerical simulation of 2D compressible flow though the tip-section turbine blade cascade with a flat profile. The OpenFOAM code was used for simulations based on the Favre-averaged Navier-Stokes equations completed by the two-equation SST turbulence model and the gama-Re_th transition model proposed by Langtry and Menter (2009). Calculations were carried out for two nominal regimes with the inlet Mach number M1 = 1.2 and isentropic outlet Mach numbers M2is = 1.7 and 1.9. Simulations of compressible flow with the supersonic inlet were focused on the relation between of the inlet Mach number and the inlet angle given by the unique incidence rule. Further, the effect of the inlet free-stream turbulence and of the outlet isentropic Mach number on the flow filed in the blade cascade was investigated. Numerical results were compared with results of optical and pressure measurements.
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Simulation of Supersonic Flow Through the Tip-Section Turbine Blade Cascade with a Flat Profile
Musil, Josef ; Příhoda, Jaromír ; Fürst, J.
The contribution presents results of the numerical simulation of 2D compressible flow through the tip-section turbine blade cascade with a flat profile and the supersonic inlet. The simulation was carried out by the OpenFOAM code using the Favre-averaged NavierStokes equations completed by the two-equation SST turbulence model and the γ-Reθ bypass transition model. Predictions carried out for nominal conditions were focused particularly on the relation between the inlet flow angle and the inlet Mach number. Further, the effect of the shock-wave/boundary layer interaction on the skin friction coefficient was investigated. Numerical results were compared with experimental data.
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