Thin front propagation in steady and unsteady cellular flows
Front propagation in two-dimensional steady and unsteady cellular flows is investigated in the limit of very fast reaction and sharp front, i.e., in the geometrical optics limit. For the steady flow, a simplified model allows for an analytical prediction of the front speed v f dependence on the stir...
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Veröffentlicht in: | Physics of fluids (1994) 2003-03, Vol.15 (3), p.679-688 |
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Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Front propagation in two-dimensional steady and unsteady cellular flows is investigated in the limit of very fast reaction and sharp front, i.e., in the geometrical optics limit. For the steady flow, a simplified model allows for an analytical prediction of the front speed
v
f
dependence on the stirring intensity
U,
which is in good agreement with numerical estimates. In particular, at large
U,
the behavior
v
f
∼U/
log
(U)
is predicted. By adding small scales to the velocity field we found that their main effect is to renormalize the flow intensity. In the unsteady (time-periodic) flow, we found that the front speed locks to the flow frequency and that, despite the chaotic nature of the Lagrangian dynamics, the front evolution is chaotic only for a transient. Asymptotically the front evolves periodically and chaos manifests only in its spatially wrinkled structure. |
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ISSN: | 1070-6631 1089-7666 |
DOI: | 10.1063/1.1541668 |