Analogy between a vortex-jet filament and the Kirchhoff elastic rod

Motion of a vortex filament with axial flow in the core, i.e. a vortex-jet filament, is governed, in the localized induction approximation, by the first two terms of the localized induction hierarchy. It is shown that permanent form of a steadily translating vortex-jet filament is identical with equilibrium form of an inextensible elastic rod of circular cross-section. A variational principle is presented for the statics of an elastic rod with respect to the director field, which manifests the origin of this analogy.