Global stability of a jet in crossflow

S. Bagheri (1) , P. Schlatter (1) , Peter J. Schmid (2) , D.S. Henningson (1)

1 Department of Mechanics [Stockholm]
2 LadHyX - Laboratoire d'hydrodynamique

A linear stability analysis shows that the jet in crossflow is characterized by self-sustained global oscillations for a jet-to-crossflow velocity ratio of 3. 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. © 2009 Cambridge University Press.

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

S. Bagheri, P. Schlatter, Peter J. Schmid, D.S. Henningson. Global stability of a jet in crossflow. Journal of Fluid Mechanics, 2009, 624 (avril), pp.33-44. ⟨10.1017/s0022112009006053⟩. ⟨hal-01002593⟩