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| Titel |
Lagrangian transport and chaos in the near wake of the flow around an obstacle: a numerical implementation of lobe dynamics |
| VerfasserIn |
J. Duan, S. Wiggins |
| 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 ; 4, no. 3 ; Nr. 4, no. 3, S.125-136 |
| Datensatznummer |
250001681
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| Publikation (Nr.) |
 copernicus.org/npg-4-125-1997.pdf |
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| Zusammenfassung |
| In this paper we study Lagrangian transport in the near wake of the
flow around an obstacle, which we take to be a cylinder. In this case, for the range of
Reynolds numbers investigated, the flow is two-dimensional and time periodic. We use ideas
and methods from transport theory in dynamical systems to describe and quantify transport
in the near wake. We numerically solve the Navier-Stokes equations for the velocity field
and apply these methods to the resulting numerical representation of the velocity field.
We show that the method of lobe dynamics can be used in conjunction with computational
fluid dynamics methods to give very detailed and quantitative information about Lagrangian
transport. In particular, we show how the stable and unstable manifolds of certain
saddle-type stagnation points on the cylinder, and one in the wake, can be used to divide
the flow into three distinct regions, an upper wake, a lower wake, and a wake cavity. The significance of the division using stable and unstable
manifolds lies in the fact that these invariant manifolds form a template on which the
transport occurs. Using this, we compute fluxes from the upper and lower wakes into the
wake cavity using the associated turnstile lobes. We also compute escape time
distributions as well as compare transport properties for two different Reynolds numbers. |
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