Vortex stability and inertial-range cascades

We consider the inviscid stability and evolution of columnar vortices whose cores consist of a disc of constant vorticity ω₁ surrounded by an annular coat of constant vorticity ω₂. For core parameters in the range suggested by vortex-tube geometries of the inertial-range eddy structure, we find the breakup of unstable cores is largely two-dimensional, particularly if the vortex is being stretched. Tentative studies of the breakup of the core, using vortex methods, are described.