A Numerical Study of Three-dimensional Vortex Breakdown
Author | : Robert Edward Spall |
Publisher | : |
Total Pages | : 268 |
Release | : 1987 |
Genre | : Fluid mechanics |
ISBN | : |
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Author | : Robert Edward Spall |
Publisher | : |
Total Pages | : 268 |
Release | : 1987 |
Genre | : Fluid mechanics |
ISBN | : |
Author | : H. L. Chen |
Publisher | : |
Total Pages | : 68 |
Release | : 1991 |
Genre | : Vortex motion |
ISBN | : |
In the present study, generation of two vortex rings and their cut-and-connect process were numerically simulated by solving three-dimensional and time-dependent Navier-Stokes equations, under conditions similar to the laboratory experiment. In order to explain the mechanism of cut-and-connect, velocity, vorticity, pressure, helicity density and energy dissipation were examined for the flow field of the cut-and-connect of vortex rings. The present study revealed that energy dissipation is an essential process for circulation cancellation during vortex tubes cutting. Based on this energy dissipation mechanism, it is concluded that the cut-and-connect of vortex tubes may occur in the limit of inviscid flows. This conclusion is particularly important to the three-dimensional discrete vortex method for computing high Reynolds number flows. Features of helicity in the three-dimensional flow field of cut-and-connect process of vortex tubes were also investigated. The relation between the helicity density and the energy dissipation function in the three-dimensional flow field was examined.
Author | : Y. Nakamura |
Publisher | : |
Total Pages | : 20 |
Release | : 1983 |
Genre | : Numerical analysis |
ISBN | : |
The vortex-filament method was applied to the simulation of vortex breakdown. The principal vortex region was represented by multiple filaments, and an axial velocity component was induced by a spiral winding of the filaments. First, an accuracy check was performed for a cylindrical swirling flow field that can be simulated to any accuracy by increasing the number of filaments. Second, an axisymmetric-type vortex breakdown was simulated, with experimental data serving asupstream conditions. The calculated axial- and theta-velocity contours show the breakdown of the vortex, including a rapid change in the vortex core, followed axially by a recovery zone and then a second breakdown. When three-dimensional initial data are used the second breakdown appears to be out of the spiral type in correspondence with experimental observations. The present method can easily be used to simulate other types of vortex breakdown or other vortex flows with axial velocity.
Author | : |
Publisher | : |
Total Pages | : 19 |
Release | : 1978 |
Genre | : |
ISBN | : |
Vortex breakdown is simulated by a three dimensional Lagrangian method using vortex filaments. The filaments are approximated by vortex elements and their velocity is computed by a Biot-Savart type law of interaction. The numerical calculations show the development of an axisymmetric bubble with a recirculation zone and resemble in many respects the results obtained in the physical experiments on vortex breakdown.
Author | : Ernst Heinrich Hirschel |
Publisher | : Springer Science & Business Media |
Total Pages | : 293 |
Release | : 2012-12-06 |
Genre | : Technology & Engineering |
ISBN | : 3540456937 |
This volume contains eighteen reports on work, which is conducted since 2000 in the Collaborative Research Programme 'Numerical Flow Simulation' of the Centre National de la Recherche Scientifique (CNRS) and the Deutsche Forschungsgemeinschaft (DFG). French and German engineers and mathematicians present their joint research on the topics 'Development of Solution Techniques', 'Crystal Growth and Melts', 'Flows of Reacting Gases, Sound Generation' and 'Turbulent Flows'. In the background of their work is the still strong growth of the performance of super-computer architectures, which, together with large advances in algorithms, is opening vast new application areas of numerical flow simulation in research and industrial work. Results of this programme from the period 1996 to 1998 have been presented in NNFM 66 (1998), and NNFM75 (2001).