Optimal velocity and density profiles for the onset of absolute instability in jets - École polytechnique Access content directly
Journal Articles Journal of Fluid Mechanics Year : 2010

Optimal velocity and density profiles for the onset of absolute instability in jets

Abstract

The absolute/convective character of the linear instability of axisymmetric jets is investigated for a wide range of parallel velocity and density profiles. An adjoint-based sensitivity analysis is carried out in order to maximize the absolute growth rate of jet profiles with and without density variations. It is demonstrated that jets without counterflow may display absolute instability at density ratios well above the previously assumed threshold rho(jet)/rho(infinity) = 0.72, and even in homogeneous settings. Absolute instability is promoted by a strong velocity gradient in the low-velocity region of the shear layer, as well as by a step-like density variation near the location of maximum shear. A new efficient algorithm for the computation of the absolute instability mode is presented.
Fichier principal
Vignette du fichier
OVS0022112010004246a.pdf (348.38 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

hal-01020674 , version 1 (09-07-2014)

Identifiers

Cite

Lutz Lesshafft, Olivier Marquet. Optimal velocity and density profiles for the onset of absolute instability in jets. Journal of Fluid Mechanics, 2010, 662 (November), pp.398-408. ⟨10.1017/s0022112010004246⟩. ⟨hal-01020674⟩
92 View
360 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More