National Repository of Grey Literature 36 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Preliminery results of conditional anaysis of the wall-friction during boundary layer transition
Jonáš, Pavel ; Mazur, Oton ; Uruba, Václav
The wall-friction is intermittently changing laminar/turbulent nature during bondary lazer transition. The indicator function is used for the determination of the transitional intermittency factor was employed for the conditional analysis of the wall friction. Namely there were derived the mean durations of the wall-friction stays in laminar and turbulent conditions and some statistical characteristics of wall-friction during the appointed conditions
Approximation of the intermittency factor distribution at bypass boundary layer transition
Jonáš, Pavel ; Mazur, Oton ; Uruba, Václav
The distribution of the imtermittency factor is discussed in the case of boundary layer by-pass transition. The approximation of Narasimha is modified for the case when the intermittency distribution does not start from zero value at the location of the transition start.
Comparison of turbulence models for impinging jet flows
Kozel, K. ; Louda, P. ; Příhoda, Jaromír
Paper deals with the comparison of various turbulence models for computation of the 2D and 3D impinging jet flows. The best agreement with experimental data was obtained for the two-layer k-L/k-eps model and Menter SST model.
Numerical simulation of the wall jet on a circullar cylinder
Příhoda, Jaromír ; Sedlář, M.
The wall jet on a circular cylinder was simulated numerically using the CFX-TASCflow software. The calculation was carried out for the relative slot height h/R=0.04 and the Reynolds number Reh from 3500 to 21000. Results obtained by the k-eps model and by the BSL and SST models proposed by Menter were compared with experimental data and with empirical relations.
Fluid dynamics 2001
Jonáš, Pavel ; Uruba, Václav
The proceedings contain 32 texts of the contributions from the conference from the fields Fluid dynamics.
Comment of the application of the intermittency factor measurement to increase the accuracy of hte determination of the boundary layer transition start
Jonáš, Pavel ; Mazur, Oton ; Stepien, M. ; Uruba, Václav
A method of the direct assessment of the intermittency factor distribution inside a transitional boundary layer under outer stream turbulence was developed and proved. It was justified that the Narasimha approximation is not accurate at such boundary itions as the basic assumption that the boundary layer upstream the start of transition is not turbulent, is not valid. The proposed modification of Narasimha formulae seems to be more accurate.
Proceedings of the seminar Topical Problems of Fluid Mechanics 2001
Příhoda, Jaromír ; Kozel, Karel
The proceedings contain 34 contributions related to problem of fluid dynamics and thermodynamics presented at the Seminar Topical Problems of Fluid Mechanics 2001.
Proceedings of the 4th seminar Euler and Navier-Stokes equations (Theory, numerical solution, application)
Kozel, Karel ; Příhoda, Jaromír ; Feistauer, M.
The proceedings contain 38 contributions related to theory, numerical solution and applications of Navier-Stokes equations presented at 4rd Seminar Euler and Navier-Stokes Equations.
Implementation and futher application of refined transition prediction methods for turbomachinery and other aerodynamics flows. /Z - 1307/
Jonáš, Pavel ; Příhoda, Jaromír
The report deals with mathematical modelling and experimental investigation of the bypass transition in boundary-layer flows. The modelling of bypass transition is based on two-layer turbulence models and an algebraic intermittency model. The effect of velocity and length scales of free-stream turbulence on the onset and the end of the transition region for flat-plate boundary layer was investigated experimentally.
On the jet-cross-flow interactions
Uruba, Václav ; Mazur, Oton ; Jonáš, Pavel ; Luxa, Martin
The results show some features of the jet-perpendicular flow interaction zone structure. The bottom part of it below the jet is of similar structure as wake behind a bluff body - cylinder, inclusive of the quasiperiodical nature of the flow structure..

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