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| Titel |
Lagrangian structures in time-periodic vortical flows |
| VerfasserIn |
S. V. Kostrykin, A. A. Khapaev, V. M. Ponomarev, I. G. Yakushkin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 13, no. 6 ; Nr. 13, no. 6 (2006-11-14), S.621-628 |
| Datensatznummer |
250011871
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| Publikation (Nr.) |
 copernicus.org/npg-13-621-2006.pdf |
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| Zusammenfassung |
The Lagrangian trajectories of fluid particles are experimentally
studied in an oscillating four-vortex velocity field. The
oscillations occur due to a loss of stability of a steady flow and
result in a regular reclosure of streamlines between the vortices
of the same sign. The Eulerian velocity field is visualized by
tracer displacements over a short time period. The obtained data
on tracer motions during a number of oscillation periods show that
the Lagrangian trajectories form quasi-regular structures. The
destruction of these structures is determined by two
characteristic time scales: the tracers are redistributed
sufficiently fast between the vortices of the same sign and much
more slowly transported into the vortices of opposite sign. The
observed behavior of the Lagrangian trajectories is quantitatively
reproduced in a new numerical experiment with two-dimensional
model of the velocity field with a small number of spatial
harmonics. A qualitative interpretation of phenomena observed on
the basis of the theory of adiabatic chaos in the Hamiltonian
systems is given.
The Lagrangian trajectories are numerically simulated under
varying flow parameters. It is shown that the spatial-temporal
characteristics of the Lagrangian structures depend on the
properties of temporal change in the streamlines topology and on
the adiabatic parameter corresponding to the flow. The condition
for the occurrence of traps (the regions where the Lagrangian
particles reside for a long time) is obtained. |
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