Frequency selection in globally unstable round jets - École polytechnique Access content directly
Journal Articles Physics of Fluids Year : 2007

Frequency selection in globally unstable round jets

Abstract

The self-sustained formation of synchronized ring vortices in hot subsonic jets is investigated by direct numerical simulation of the axisymmetric equations of motion. The onset of global instability and the global frequency of synchronized oscillations are examined as functions of the ambient-to-jet temperature ratio and the initial jet shear layer thickness. The numerical results are found to follow the predictions from nonlinear global instability theory; global instability sets in as the unperturbed flow is absolutely unstable over a region of finite streamwise extent at the inlet, and the global frequency near the global instability threshold corresponds to the absolute frequency of the inlet profile. In strongly supercritical thin shear layer jets, however, the simulations display global frequencies well above the absolute frequency, in agreement with experimental results. The inner structure of rolled-up vortices in hot jets displays fine layers of positive and negative vorticity that are produced and maintained by the action of the baroclinic torque. © 2007 American Institute of Physics.
Fichier principal
Vignette du fichier
lesshafft2007rp-2pp.pdf (697.87 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

hal-01023085 , version 1 (20-07-2014)

Identifiers

Cite

Lutz Lesshafft, Patrick Huerre, Pierre Sagaut. Frequency selection in globally unstable round jets. Physics of Fluids, 2007, 19 (5), pp.054108. ⟨10.1063/1.2732247⟩. ⟨hal-01023085⟩
217 View
372 Download

Altmetric

Share

Gmail Facebook X LinkedIn More