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3D Micromodels of Porous Structures
Pražák, Josef
Speaking about modeling in technical sciences, we have in mind an analysis of mathematical (computational) or physical analogies of objects to be studied. Physical modeling means a systematic building of physical objects heaving some analogy with the studied physical reality. For the models of porous structures, the notion micromodels has been introduced. The micro- means that the model represents only a small fraction of real porous structure and that some essential schematization of reality is included. The difference between a micromodel and a simple probe of a natural porous material (a small volume of soil, sand, etc.) consist in the fact that some exact geometrical information is ahead. Very often, the real porous space is schematized into a regular graph network. The Lenormand´s micromodels are 2D objects where a random square network has been cut in a sophisticated way into a layer of resin between two layers of plexiglass.
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Implementation of pressure-correction algorithm with AUSM into openFOAM
Kožíšek, Martin ; Fürst, J.
This paper shows results of the project concerned with implementation of the Advection Upstream Splitting Method (AUSM) into OpenFOAM. AUSM is well suited for calculations of transonic flows. Authors have recently presented the implementation of explicit AUSM method. In this article the authors aim to improve convergence behaviour. This was achieved by treating acoustic terms implicitly following the approach proposed by Dick and Nerinckx. The system of equations became semi-implicit and the fully segregated pressure-correction algorithm was implemented. Presented numerical solutions of 2D and 3D inviscid transonic flows through a channel were obtained using explicit as well as new implicit implementation of AUSM in OpenFOAM.
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Computation of flow around heated cylinder
Pech, Jan
Results of two dimensional numerical simulation of flow around heated cylinder will be presented. The focus is on frequency of vortex shedding in regime of low Reynolds numbers. Computational method based on scheme of spectral elements for Navier-Stokes equations, modified to involve temperature dependent viscosity.
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Wind tunnel study of dispersion in different urban area configurations
Chaloupecká, Hana ; Jurčáková, Klára ; Kellnerová, Radka ; Kukačka, Libor ; Jaňour, Zbyněk
The object of this study is modelling of pollution dispersion in a wind tunnel. We’ve used the inverse method of modelling to this.That means a given location of detector of pollution and a net of points where we placed one by one a point source. We’ve studied this probem for different set-ups of buildings and approach flow directions. A sensitivity of concentration diffusion upon on the type of set-up of buildings and approach flow direction has been demonstrated from the results of experiment. The best se-up of buildings due to the measurement of concentration in two fixed points has been found.
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Numerical model of saltation in open channel with rough bed
Kharlamova, Irina ; Vlasák, Pavel
The present contribution deals with a numerical modelling of a saltation of solid spherical particle in turbulent flow along rough bed in the open channel. The goal of the research is to obtain the dependences of average characteristics of particle saltation motion (as length and height of one particle jump) on flow parameters (which can be characterized e.g. by shear velocity and water depth) and bed roughness. The suggested dependences and calculated results are compared with analogical relationships introduced by other authors in literature.
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Microbubble Generation by Fluidics. Part II: Bubble Formation Mechanism
Tesař, Václav
Author develops a facility for generation of sub-millimetre sized air bubbles in water. A promising and economically viable method, based on author's earlier experience, is fragmentation of bubbles by oscillation while they are still at the aerator exit locations. Understanding the mechanism by which the oscillation affects bubble formation is a pre-requisite to new aerator design. Results obtained so far reveal a strange bubble size independence on the applied acoustic power, frequency of oscillation and the character of aeratoir body.
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