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Modelling of exoplanetary atmospheric circulation
Novák, Jiří ; Brechler, Josef (advisor) ; Raidl, Aleš (referee)
In this thesis we study the properties of exoplanetary atmospheres. The first part describes methods and instruments for searching exoplanets, statistics of discovered exoplanets and the sampling factor. The second part describes the properties of chosen planets and moons in the Solar system (Venus, Mars and Titan) and also possible properties of the exoplanetary atmospheres that are only briefly understood. The third part describes the atmospheric models which incorporate full 3D model of the atmosphere, dynamical core, shallow-water model and 1D spherically-symmetric model. We also show the results of exoplanetary atmospheric models published in the scientific journals. This part also describes the icosahedral geodetic grid that is advantageous for the global climatic models, and also discretisation on sphere and the application of the operators (gradient, divergence, vorticity) on geodetic grid. The fourth part discusses results of the numerical solution of the atmospheric circulation with the forcing on geodetic grid. In this part we also show global maps of the variables after a particular time of the numerical integration and also the evolution of the variables at chosen points in time. In the discussion part we examine the results of our program. The results of the numerical integrations (chosen...
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Flow and diffusion characteristics inside the urban area
Chaloupecká, Hana ; Jaňour, Zbyněk (advisor) ; Brechler, Josef (referee)
Title: Flow and diffusion characteristics inside the urban area Author: Hana Chaloupecká Department: Department of meteorology and enviroment protection Supervisor: prof. RNDr. Zbyněk Jaňour, DrSc., IT AS CR, v. v. i. Supervisor's e - mail: janour@it.cas.cz Abstract: Uniqueness of different towns, consists of various shapes of buildings. The main topic of this work is to compare concentration diffusion within groups of buildings of various types. We pursued houses made of single blocks of two different lengths - they were placed parallel or in courtyards. For research of pollution diffusion within the housing estates a method of physical modelling has been used. For this purpose we summarized a theory of atmospheric boundary layer and physical modelling at first. Then we pursued experiments. Measuring took place in a model in scale 1 : 300 inside an aerodynamic wind tunnel of the Institute of Thermomechanics AS in Nový Knín. We checked out the requirements placed on similarity of the real boundary layer and boundary layer modelled in the tunnel. By the measuring of concentration in urban areas we weren't watching a plume from the pollution source but we were studying an inversion task. We measured concentrations in two fixed points from different point sources inside the defined areas. A sensitivity of...
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Immersed boundary methods in air-flow models
Benešová, Stanislava ; Brechler, Josef (advisor) ; Hron, Jaroslav (referee)
This work focuses on the immersed boundary methods and their aplications to modeling flow in urban areas. In the first part Navier-Stokes equations are derived. In the second part we describe the main priciples of the immersed boundary methods. Two main groups of methods are introduced accompanied by examples. Based on the properties of these methods one method is selected which is suitable to describe the geometry in the modeling of airflow in urban areas. The method MIB from the article Mark et al. (2008) is chosen. This method is compared with the method introduced in the article Kim et al. (2001). Both methods are described in detail and compared according to several criteria in the third chapter. Such a criterion is the accuracy of the continuity equation. Simulations of a several test problems were carried out for the purpose of comparison of the chosen methods. Flow around a circular cylinder and a square cylinder for Reynolds numbers of 10 and 30 is solved. The divergence value of~the~velocity field in the modeled area was observed during the calculation of both methods. The results yields that MIB method solves the continuity equation more accurate.
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Political legislation cycle in the Czech Republic
Brechler, Josef ; Geršl, Adam (advisor) ; Rychetník, Luděk (referee)
There is a wide range of theories that try to explain interactions between politics end economy that are referred as political cycles. Majority of these theories aims at analysis of changes in economic outcomes that are related to elections or other phenomena in the political reality. To induce at least some of these changes it is necessary to alter a country's legislation which leads to emergence of political legislation cycles - changes in legislation activity over time in an electoral term. The aim of this work is to study political legislation cycle in the legislative system of the Czech Republic. Obtained results suggest that elections timing has certain impact on legislation activity. As electoral term matures and upcoming elections are getting closer an increase is observed in the legislation activity.
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Thermally stratified atmospheric flow modelling
Jirk, Aleš ; Brechler, Josef (advisor) ; Jaňour, Zbyněk (referee)
In this thesis there is simulated an incompressible laminar flow in a higher-order accuracy around a circle cylinder with usage of an immersed boundary method and around a cylinder with a square cross-section with an influence of a thermal stratification. In the theoretical part the system of Navier-Stokes equations with Bussinesq approximation is derived and the methods for simulating are described. Fifth order WENO shock-capturing scheme reconstructs advections terms on the boundaries of control volumes. An explicit fourth-order Runge-Kutta scheme solves the first step of a fractional steps method. The obstacle with the circle cross-section is described by the immersed boundary method. In the implementation section there is interpreted the structure of programs for 2D cases. In the section Numerical experiments there is realized testing of the examples with the exactknown results the linear hyperbolic equations, the Burgers equations and the Euler equations and of a square cavity flow with Reynolds numbers of 100,1000 and 5000 with known numerical results for the Navier-Stokes equation. There is solved the flow around a square (and a circle) cylinder for Reynolds numbers 30; 200. Strouhal numbers are computed for von Kármán vortex street. Finally the flow around a square cylinder with influence of thermal...
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