Numerical study of the evolution of vortices in a linearly stratified fluid

This paper presents a numerical study in which the evolution of vortices in a stratified fluid is compared to the evolution of two-dimensional vortice s. The influence of the Reynolds number and the Froude number are investiga ted, for the evolution of axisymmetric vortices, for their azimuthal instab ility and for the subsequent formation of tripoles. It is found that due to radial diffusion axisymmetric vortices with various initial vorticity prof iles all evolve towards the same profile. This evolution reduces the growth of azimuthal instabilities which may lead to the formation of a tripole. F or vortices in a stratified fluid the effect of the ambient stratification on the evolution of the vortices is investigated. It is found that a proces s of vortex stretching, which becomes more pronounced for increasing Froude numbers, leads to a weaker tripole formation.