National Repository of Grey Literature 18 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
On the problem of singular limit
Caggio, Matteo ; Ducomet, B. ; Nečasová, Šárka ; Tang, T.
We consider the problem of singular limit of the compressible Euler system confined to a straight layer Ωδ = (0, δ)×R², δ > 0. In the regime of low Mach number limit and reduction of dimension the convergence to the strong solution of the 2D incompressible Euler system is shown.
The hydrostatic approximation of compressible anisotropic Navier-Stokes equations
Gao, H. ; Nečasová, Šárka ; Tang, T.
The aim of the paper is to give a rigorous derivation of the hydrostatic approximation by taking the small aspect ratio limit to the Navier-Stokes equations. The aspect ratio (the ratio of the depth to horizontal width) is a geometrical constraint in the general large scale geophysical motions meaning that the vertical scale is signi cantly smaller than horizontal.
Note on the mathematical analysis of the motion of a rigid body in a generalized incompressible Navier-Stokes fluid
Al Baba, H. ; Ghosh, Amrita ; Muha, B. ; Nečasová, Šárka
Wedeal with a fluid-structure interaction problem: a motion of the rigid body inside a bounded domain filled by a fluid. We consider a viscous incompressible fluid described by the generalized incompressible Navier-Stokes equations which include cases of Newtonian and non-Newtonian f luids. The fluid and the rigid body are coupled via the Navier slip boundary conditions and the motion of the solid is governed by Newton’s laws. We also investigate the case of the nonlinear slip condition.The main results assert the existence of strong solutions, in an Lp − Lq setting.
Qualitative properties of radiation magnetohydrodynamics.
Kobera, Marek ; Nečasová, Šárka (advisor) ; Franců, Jan (referee) ; Neustupa, Jiří (referee)
We consider a simplified model based on the Navier-Stokes-Fourier system coupled to a transport equation and the Maxwell system, proposed to describe radiative flows in stars. We establish global- in-time existence for the associated initial-boundary value problem in the framework of weak solutions. Next, we study a hydrodynamical model describing the motion of internal stellar layers based on compressible Navier-Stokes-Fourier-Poisson system. We suppose that the medium is electrically charged, we include energy exchanges through radiative transfer and we assume that the system is steadily rotating. We analyze the singular limit of this system when the Mach number, the Alfven number, the Peclet number and the Froude number go to zero in a certain way and prove convergence to a 3D incompressible MHD system with a stationary linear transport equation for transport of radiation intensity. Finally, we show that the energy equation reduces to a steady equation for the temperature corrector.
Recent results on the problem of motion of viscous fluid around a rotating rigid body
Deuring, P. ; Kračmar, Stanislav ; Nečasová, Šárka
We consider the linearized incompressible flow around rotating and translating body in the exterior domain R³D‾, where D⊂R³ is open and bounded, with Lipschitz boundary. We derive the pointwise estimates for the pressure. Further, we consider the linearized problem in a truncation domain DR:=BRD‾ of the exterior domain R³D‾ under certain artificial boundary conditions on the truncating boundary ∂BR, and then compare this solution with the solution in the exterior domain R³D‾ to get the truncation error estimate.
Note on the problem of compressible non-Newtonian fluids
Caggio, M. ; Nečasová, Šárka
The aim of the paper is to consider the compressible non-Newtonian fluids of power law type when the viscosity coeffcients depend not only on invariants of velocity field but also on the density. We introduce approximation scheme using model of multipolar fluids. After then passing with higher viscosity to zero we get the measure valued solution of the problem.
Qualitative properties of radiation magnetohydrodynamics.
Kobera, Marek ; Nečasová, Šárka (advisor) ; Franců, Jan (referee) ; Neustupa, Jiří (referee)
We consider a simplified model based on the Navier-Stokes-Fourier system coupled to a transport equation and the Maxwell system, proposed to describe radiative flows in stars. We establish global- in-time existence for the associated initial-boundary value problem in the framework of weak solutions. Next, we study a hydrodynamical model describing the motion of internal stellar layers based on compressible Navier-Stokes-Fourier-Poisson system. We suppose that the medium is electrically charged, we include energy exchanges through radiative transfer and we assume that the system is steadily rotating. We analyze the singular limit of this system when the Mach number, the Alfven number, the Peclet number and the Froude number go to zero in a certain way and prove convergence to a 3D incompressible MHD system with a stationary linear transport equation for transport of radiation intensity. Finally, we show that the energy equation reduces to a steady equation for the temperature corrector.
Note on the problem of dissipative measure-valued solutions to the compressible non-Newtonian system
Al Baba, Hind ; Caggio, Matteo ; Ducomet, B. ; Nečasová, Šárka
We introduce a dissipative measure-valued solution to the compressible non-Newtonian system. We generalized a result given by Novotný, Nečasová [14]. We derive a relative entropy inequality for measure-valued solution as an extension of the classical entropy inequality introduced by Dafermos [2], Mellet-Vasseur [11], Feireisl-Jin-Novotný [5].
Valuation of Exterier Beton, s.r.o.
Nečasová, Šárka ; Jandásek, Radek (referee) ; Zinecker, Marek (advisor)
Goal of this Diploma thesis is determination of the value of Exterier Beton, s.r.o. company on the methods based of discounted cash flow. Theoretical part is focused on primary definitions, definition of value and the reasons why to carry out of valuation. There are also mentioned parts of valuation method and specification process during valuation in diploma thesis. The practical part deals with the characteristics of the company, strategic analysis, evaluation of the financial health of the company, setting up of financial plan and application of selected methods of valuation.
Some notes about the homogenization problem for the Navier-Stokes equations
Feireisl, Eduard ; Namlyeyeva, Yuliya ; Nečasová, Šárka
We study the homogenization problem for the evolutionary Navier-Stokes system under the critical size of obstacles. Convergence towards the limit system of Brinkman's type is shown under very mild assumptions concerning the shape of the obstacles and their mutual distance.

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