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Dual-time stepping method applied to a numerical solution of unsteady incompressible flow with a vibrating profile
Honzátko, R. ; Horáček, Jaromír ; Kozel, K.
The paper presents numerical solution of two-dimensional incompressible flow in the interaction with a vibrating profile. The profile has two degrees of freedom. Mathematical model is represented either by the Euler equations in the case of inviscid flow or the Navier-Stokes equations in the case of viscous flow. Finite volume method is used as a discretization method. The dual-time stepping method is applied to unsteady simulations. This method provides a possibility to develop a time-accurate time-marching scheme for unsteady incompressible flows. Computational domain deformation due to the profile motion are treated using the Arbitrary Lagrangian-Eulerian method (ALE). Numerical schemes used for unsteady flow calculations are implemented in a form satisfying the geometric conservation law (GCL).
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Vibrace vyvolané proudem tekutiny 2008
Zolotarev, Igor ; Horáček, Jaromír
Flow-induced vibrations and noise continue to cause problems in a wide range of engineering applications, ranging from mechanical and aerospace engineering, civil engineering and ship and offshore structures to power generation and chemical processing. These proceedings bring together 139 papers dealing with a variety of topics relating to flow-induced vibration and noise, such as:vortex-induced vibration, vibration of heat-exchanger tube bundles,progress in fluid-structure interaction theory and CFD simulations, flow-sound interaction, biomechanics of voice and hearing, thermo-acoustic instabilities, vibration of hydraulic structures, gates, turbomachines nad piping systems. The contents of this publication constitute a „mixture“ of investigations by those working on the mechanisms of vibration and means of their alleviation, and studies by those in industry who draw on the present state of knowledge of these mechanisms to avoid or solve flow induced vibratin and noise problems in industrial and other applications.
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Analýza stability rovnovážné polohy a odezvy rotorů uložených v kapalinných ložiskách a majících kotouč ponořený v nesmáčivé kapalině
Zapoměl, Jaroslav
In a number of technological applications the rotors supported by fluid film bearings have the discs submerged in various liquids. Lateral vibration of such rotors is significantly influenced by their interaction with the medium in the surrounding space. A computer modelling method represents an important tool for investigation of their behaviour. The approach to analysis of vibration of small amplitudes of structures submerged in liquids is based on modification of the Navier Stokes equations leading to the Laplace one. The fluid film bearings are usually implemented into the computational models by means of nonlinear force couplings. The pressure distribution in the full oil film is governed by a Reynolds equation and in cavitated areas the pressure remains constant. The motion of a rotor supported by short hydrodynamic bearings, excited by imbalance forces, and having a disc submerged in inwettable liquid was investigated.
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Postup pro zkoumání stability rovnovážné polohy a nelineární odezvy rotoru uloženého v kapalinných ložiskách a majícím kotouč ponořený v neviskózní, nesmáčivé kapalině
Zapoměl, Jaroslav
Lateral vibration of rotors is significantly influenced by their supports and by their interaction with the medium in the ambient space. If the disc of the rotor is submerged in a liquid and if it vibrates, the pressure field is induced and the liquid acts by a force on the wall of the disc. It is assumed that the disc performs oscillations only with small amplitudes and it enables to describe the produced pressure field by a Laplace's equation and by the relation for the boundary conditions. The liquid is inwettable and it means that it does not lean to the disc surface and therefore no tangential forces acting on the disc are produced. The resulting force is obtained by integration of the pressure distribution around the circumference and along the height of the submerged part of the disc. Its components are proportional to the disc accelerations and it implies that the negatively taken coefficients of proportionality can be considered as additional masses.
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FE model of interaction between oscilating vocal folds and acoustic space of the vocal tract
Švancara, Pavel ; Hrůza, V.
A 2D and 3D finite element models of interaction between oscillating vocal folds and acoustic space of the vocal tract were developed in program system ANSYS, where the only one driving parameter is velocity of flow under vocal folds. The interaction is based on Sequential Coupled Analysis, where results of transient fluid analysis in ANSYS/Flotran CFD are used as loads for transient analysis of motion of the vocal folds. Models respect large deformations, vocal folds pretension, contact of vocal folds, flow separation and compressible flow.
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