National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Comparison of Finite Volume and Spectral/HP Methods on Navier - Stokes Equations for Unsteady Incompressible Flow
Pech, Jan ; Louda, Petr
We provide a comparison of solutions to the incompressible Navier-Stokes equations obtained using codes based on finite volume and spectral element methods. Convergence properties are compared on test case with analytical solution. The dependence of Strouhal and Reynolds numbers for flow over a cylinder is reconstructed for both methods.\n\n
Flow in Branched Channel
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
Flow in a branched channel is investigated experimentally using the PIV method. The branches are issuing from the main cannel perpendicularly, all channels are of rectangular cross-section. The time-mean flow-fields in the main channel and in the branches are studied in details.
The Influence of Different Geometries of Human Vocal Tract Model on Resonant Frequencies
Valášek, Jan ; Sváček, Petr ; Horáček, Jaromír
This paper presents the transfer function approach in order to determine the acoustic resonant frequencies of a human vocal tract model. The transfer function is introduced here as an acoustic pressure ratio between input amplitude at glottis position and output amplitude at mouth opening given by the solution of Helmholtz equation. This equation is numerically approximated by finite element method. The influence of different boundary conditions are studied and also different locations of excitation and microphone. Four different vocal tract geometries motivated by vocal tract geometry for vowel [u:] are investigated. Its acoustic resonance frequencies in range 100 - 2500 Hz are computed and compared with published results. Further, the transient acoustic computation with different acoustic analogies are performed. The frequency spectra of Lighthill analogy, acoustic wave equation and perturbed convective wave equation are compared, where the vocal tract model with best frequency agreement with published results was chosen. The dominant frequencies correspond with predicted frequencies of transfer function approach.\n

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