Instabilit´ e des ´ ecoulements tournants stratifi´ es

In this work we analyse the linear stability of two rotating flows in a fluid linearly stratified along the vortex axis : the Lamb-Oseen vortex and the potential flow around a rotating cylinder. We show that both flows become unstable in stratified fluids. We use a Chebyshev spectral collocation code to find the viscous threshold of the instability. We also present the experimental results for the two flows in agreement with the numerical results.