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Anelastic deformation of planetary bodies
Vach, Dominik ; Čadek, Ondřej (advisor) ; Běhounková, Marie (referee)
Observations indicate an existence of subsurface oceans for some of the icy moons in the Solar System which are heated by the tidal forces. In order to describe this anelastic deformation, the methods well-known from the continuum mechanics were employed, and thus the dissipation was calculated for various bodies. In the thesis, Maxwell and Kelvin-Voigt model were compared in their ability to predict the heating power of the bodies. In contrast to the Maxwell model, the Kelvin-Voigt model, which is generally not used in geophysics, repre- sents reversible processes, and thus could explain the effects which are otherwise explained only by the gravity. A program in Fortran was developed in order to compare the models by modelling 3D anelastic deformation of planetary bodies under the effect of tidal forces. The results indicate the predicted power can be various for both models and Kelvin-Voigt model could be used e.g. to describe short run deformation processes. 1
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Anelastic deformation of planetary bodies
Vach, Dominik ; Čadek, Ondřej (advisor) ; Běhounková, Marie (referee)
Observations indicate an existence of subsurface oceans for some of the icy moons in the Solar System which are heated by the tidal forces. In order to describe this anelastic deformation, the methods well-known from the continuum mechanics were employed, and thus the dissipation was calculated for various bodies. In the thesis, Maxwell and Kelvin-Voigt model were compared in their ability to predict the heating power of the bodies. In contrast to the Maxwell model, the Kelvin-Voigt model, which is generally not used in geophysics, repre- sents reversible processes, and thus could explain the effects which are otherwise explained only by the gravity. A program in Fortran was developed in order to compare the models by modelling 3D anelastic deformation of planetary bodies under the effect of tidal forces. The results indicate the predicted power can be various for both models and Kelvin-Voigt model could be used e.g. to describe short run deformation processes. 1
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Termální vývoj Saturnova měsíce Enceladu
Kozoň, Marek ; Čadek, Ondřej (advisor) ; Běhounková, Marie (referee)
We study thermal evolution of Enceladus on very long time scales. In order to do so, we created a Fortran program modeling tidal deformation and thus induced heat dissipation as well as conductive transport of the heat in the body of the moon. Effect of long-lived radioactive isotopes decay in the core on the heat generation is included. We show the dependence of a thermal scenario character on different minimal viscosity and constant eccentricity values and study chosen cases in detail. We further demonstrate that, if orbital eccentricity evolution is incorporated, its initial value has no essential effect on the thermal evolution result, with the body always freezing quickly. Lastly, we examine the dependence of a thermal scenario on added values of hydrothermal heating power from the core and present that a power magnitude can be found, with which the satellite does not freeze, nor overheats in the first 4 billions of years what is necessary for maintaining a thermal activity on Enceladus since its formation to the present time. 1
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Thermal relations leading to the formation of gaseous phase within the ice covering lakes and ponds
Hrubá, Jolana ; Kletetschka, Günther (advisor) ; Dědeček, Petr (referee)
When cutting an ice from lakes and ponds gaseous phase displays often ubiquitous bubble textures along the ice thickness. The occurrence of bubbles (enclosures filled with the gas) in ice relates to a content of the dissolved gas in the lake/pond water prior to freezing over the surface. When water freezes, dissolved gases are rejected and redistributed at the ice-water interface, depending on the saturation ratio between the gas and water. If the concentration of dissolved gases surpasses a critical value (as freezing progresses), the water at the interface becomes supersaturated, and gas bubbles nucleate and grow to a visible size along the interface. The bubbles generated at the ice-water interface are either incorporated into the ice crystal as the ice-water interface advances, thus forming gas pores in the ice, or released from the interface. If there is incorporation or release is determined by several factors. The bubbles nucleated at the advancing ice-water interface may be characterized by concentration, shape, and size, which depend on growth rate of ice, the amount of gases dissolved in water, and the particulate content of water. This work focused on the relation between growth rates of the ice and the occurrence of bubbles in the pond ice. I monitored the temperature of the ice formed...
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