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Article

Global stability of a jet in cross-flow

Authors: Bagheri, S., Schlatter, P., Schmid, P.J., Henningson, D.S.H.
Document Type: Article
Pubstate: Published
Journal: J. Fluid Mech.
Volume: 624   33-44
Year: 2009

Abstract

A linear stability analysis shows that the jet in cross-flow is characterized by self-sustained global oscillations for a jet-to-cross-flow velocity ratio of three. A fully three-dimensional unstable steady-state solution and its associated global eigenmodes are computed by direct numerical simulations and iterative eigenvalue routines. The steady flow, obtained by means of selective frequency damping, consists mainly of a (steady) counter-rotating vortex pair (CVP) in the far field and horseshoe-shaped vortices close to the wall. High- frequency unstable global eigenmodes associated with shear layer instabilities on the CVP and low-frequency modes associated with shedding vortices in the wake of the jet are identified. Furthermore, different spanwise symmetries of the global modes are discussed. This work constitutes the first simulation-based global stability analysis of a fully three-dimensional base flow.