Abstracts - KTH Mechanics

Instability of an axisymmetric vortex in a stably stratified
fluid
S. Le Dizès ∗ , P. Billant †
The stability of a vertical vortex in a stably stratified fluid is considered by analytical
and numerical methods. We show, in a general setting, that a centrifugally
stable vortex can be destabilized by gravity wave radiations when the Froude number
is small. The analytical study is based on a large axial wavenumber asymptotic analysis
1,2 of the inviscid perturbation equations under the Boussinesq approximation. By
matched asymptotic methods, we demonstrate the existence of unstable modes for
all non-zero azimuthal wavenumbers m satisfying |m|