Global linear stability of a model subsonic jet

Xavier Garnaud (1) , Lutz Lesshafft (1) , Patrick Huerre (1)

1 LadHyX - Laboratoire d'hydrodynamique

The global stability of a subsonic jet is investigated using a model base flow designed to fit experimental results for turbulent mean flows. Eigenmodes are computed for axisymmetric perturbations in order to investigate the nature of typically observed large-scale coherent oscillations ("preferred mode"). We do not find evidence that this preferred mode corre- sponds to the least damped global mode. Non-modal stability is also considered through the computation of optimal perturbations. Although non-axisymmetric perturbations (in particular for azimuthal wavenumber m = 1) are subject to larger transient growth, these reach their peak amplitude far downstream of the potential core, and therefore they are less likely to be observed.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Xavier Garnaud, Lutz Lesshafft, Patrick Huerre. Global linear stability of a model subsonic jet. AIAA Paper, 2011, pp.2011-3608. ⟨hal-00716674⟩