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Numerical Solution of 3D Airflow in Channel Representing a Vocal Tract
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
This study deals with the numerical solution of a 3D compressible flow of a viscous fluid in a channel for low inlet airfloe velocity. the channel is a simplified model of the glottal space in the human vocal tract. The system of Navier-Stokes equations has been used as mathematical model of laminar flow of the compressible viscous fluid in a domain. The numerical solution is implemented using the finite volume method (FVM)and the predictor-corrector MacCormack scheme with artifical viscosity using a grid of quadrilateral cells.
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Numerical experiments modelling turbulent flows
Trefilík, Jiří ; Kozel, Karel ; Příhoda, Jaromír
The paper deals with modification of the transition model with the algebraic equation for the intermittency coefficient proposed originally by Straka and Příhoda (2010) for the bypass transition for modelling of the transition at low free-stream turbulence. The modification is carried out using accessible experimental data for the flat-plate flow. Further, the three-equation k-kL-omega model proposed by Walters and Cokljat (2008) was used for the modelling of the transition at low free-stream turbulence. Both models were tested by means of the incompressible flow around airfoils at moderate and very low free-stream turbulence.
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Numerical experiments for turbulent flows
Trefilík, Jiří ; Kozel, Karel ; Příhoda, J.
The aim of the work is to explorethe possibilities of modelling transonic flowsin the internal and external aerodynamics. Several konfigurationswere analyzed and calculations were performed using both inviscid and viscous models of flow. Viscous turbulent flows have been simulated using either zero equation algebraic Baldwin-Lomax model and two equation k - w model in its basic version and improved TNT variant. The numerical solution was obtained using Lax-Wendroff scheme in the MAcCormack from on structured non-ortogonal grids. Artificial dissipation was added to improve the numerical stability. Achieved results are compared with experimental data.
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Unsteady flows in convergent channel with stationary walls
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
A current challenging question is a mathematical and physical description of the mechanism for transforming the airflow energy in human vocal tract (convergent channel) into the acoustic energy representing the voice source in humans. Goal of this work is to describe mathematical model of flow in 2D convergent channel which involves attributes of real flow as is “Coanda phenomenon”, vortex convection and diffusion, jet flapping etc. along with lower call on computer time, due to later extension in 3D channel flow.
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Numerical comparison of unsteady compressible viscous flow in convergent channel
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
This study deals with a numerical solution of a 2D flows a compressible viscous fluids in a convergent channel for low inlet airflow velocity. Three governing systems – Full system, Adiabatic system, Iso-energetic system based on the Navier-Stokes equations for laminar flow are tested. The numerical solution is realized by finite volume method and the predictor-corrector MacCormack scheme with Jameson artificial viscosity using a gird of quadrilateral cells. This unsteady grid of quadrilateral cells is considered in the form of conservation laws using Arbitrary Lagrangian-Eulerian method. The numerical results, acquired from a developed program. Are presented for inlet velocity ûĄ = 4,12ms-1 and Reynolds number Re = 4 x 103.
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