Wyniki wyszukiwania - BazTech

1

Acoustic carpets

Janowicz M., Kaleta J., Wrzeciono P., Zembrzuski A.

Machine Graphics and Vision

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2016

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Vol. 25, No. 1/4

3--12

EN

Initial-boundary value problem for linear acoustics has been solved in two spatial dimensions. It has been assumed that the initial acoustic field consists of two Gaussian distributions. Dirichlet boundary conditions with zero acoustic pressure at the boundaries have been imposed. The solution has been obtained with the help of a split-operator technique which resulted in a cellular automaton with uncountably many internal states. To visualize the results, the Python library matplotlib has been employed. It has been shown that attractive graphical output results in both the transient and stationary regimes. The visualization effects are similar to, but different from, the well-known quantum-mechanical carpets.

2

Global solutions of the 2D Euler equations, starting with the work of Witold Wolibner

Székelyhidi Jr. L.

Wiadomości Matematyczne

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2012

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T. 48, Nr 2

257--269

3

Numerical Method for Modeling of Acoustic Waves Propagation

Dykas S., Wróblewski W., Rulik S., Chmielniak T.

Archives of Acoustics

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2010

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Vol. 35, No. 1

35-48

EN

In this paper, numerical results of modeling of acoustic waves propagation are presented. For calculation of the acoustic fluctuations, a solution of the full non-linear Euler equation is used. The Euler equations are solved with the use of a numerical scheme of third-order accuracy in space and time. The paper shows a validation process of the described method. This method is suitable also for an aerodynamic noise assessment on the basis of unsteady mean flow field data obtained from a CFD calculations. In such case this method is called a hybrid CFD/CAA method. The proposed method is numerically decoupled with CFD solution, therefore the information about the mean unsteady flow field can be obtained using an arbitrary CFD method (solver). The accuracy of the acoustic field assessment depends on the quality of the CFD solutions. This decomposition reduces considerably the computational cost in comparison with direct noise calculations. The presented Euler acoustic postprocessor (EAP) has been used for modeling of the acoustic waves propagation in a cavity and in the flow field around a cylinder and an aerodynamic profile.

4

Matematyczny opis ruchu chińskiego bączka

Grzesikiewicz W.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2003

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z. 20

147-152

PL

W pracy jest przedstawiony matematyczny opis ruchu bączka. Opis ten uwzględnia siły reakcji i tarcia działające w styku bączka z podłożem oraz uderzenie, powstające w czasie zmiany pozycji. Do matematycznego opisu ruchu bączka wykorzystano parametry Eulera [5] oraz model więzów niedoskonałych prezentowany w pracy [2]. Na podstawie sformułowanego opisu opracowano komputerową symulację ruchu bączka. W celu identyfikacji parametrów modelu opracowano projekt, a następnie wykonano bączek.

EN

In the paper a mathematical description of the top motion will be given. The description takes into account the reaction forces, friction acting in the contact of the top and the surface and the impact occurring during changing the position. To describe motion of the Chinese top the Euler parameters [5] and the model of non-ideal constraints [2] have been employed. The Chinese top has been manufactured and the parameters of its model have been identified The mathematical description has been used to write a computer simulation program of the top motion.

5

Preliminary analysis of the fluid flow in screw compressors

Svigler J., Vimmr J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2000

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z. 12

79-82

EN

In addition to kinematic and dynamic analyses of screw compressors it is necessary to turn our attention to the internal fluid dynamics of the screw compressors. This paper presents numerical computation of compressible inviscid flow in the work space of the screw compressor and through the gaps on its boundary. The mathematical model is described by the conservative system of euler equations. The numerical solution of this system is based on a finite difference and finite volume methods utilized on a structured quadrilateral mesh. The results are verified with the software package Fluent 5.0.2.

6

The numerical study of 3D flutter in a transonic blade row

Gnesin V., Rządkowski R., Kolodyazhnaya L

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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1999

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nr 115

149--158

EN

A three - dimensional nonlinear time - marching method and numerical analysis of 3D flutter for oscillating blade row has been presented. The approach is based on the solution of the coupled fluid - structure problem in which the aerodynamic and structural dynamic equations are integrated simultaneously in time, thus providing the correct formulation of a problem, as the interblade phase angle at which a stability (instability) would occur is a part of solution. The ideal gas flow around multiple interblade passages (with periodicity on the whole annulus) is described by the unsteady Euler equations in conservative form, which are integrated by using the explicit monotonous second - order accurate Godunov - Kolgan finite - volume scheme and moving grids. In he structure analysis the modal approach is used. The natural frequencies and modal shapes of the blade were calculated by using the different models: 3D finite element model; 1D blade model is of a one-dimensional beam described by an extended beam-theory including all important effects on a rotating blade.