Instabilities of a columnar vortex in a stratified fluid

Patrice Meunier (1) , Nicolas Boulanger , Xavier Riedinger , Stéphane Le Dizès

1 IRPHE - Institut de Recherche sur les Phénomènes Hors Equilibre

In this paper, we show that the presence of a vertical density gradient can destabilise a Gaussian vortex in two different ways. First, when the vortex axis is slightly tilted with respect to the vertical and if its Froude number is larger than one, the vortex exhibits strong axial flows inside a critical layer, which lead to a violent three-dimensional instability. Second, when the vortex axis is vertical, the vortex is weakly unstable by emission of internal gravity waves. Theoretical predictions for both instabilities are compared with experimental evidences.

Domains: Fluid mechanics [physics.class-ph]; Fluids mechanics [physics.class-ph]

Patrice Meunier, Nicolas Boulanger, Xavier Riedinger, Stéphane Le Dizès. Instabilities of a columnar vortex in a stratified fluid. IUTAM Symposium on Turbulence in the Atmosphere and Oceans, Dec 2008, Cambridge, United Kingdom. ⟨10.1007/978-94-007-0360-5_17⟩. ⟨hal-00426851⟩