Hydrodynamic instability of axisymmetric flows of an ideal fluid with an interface

An analysis is made of the instability of nonmixing rotational-translational flows in layers of an ideal fluid interacting through an interface. In particular, attention is given to annular cylindrical jets, circular capillary jets, and annular fluid layers on internal and external cylindrical surfaces. Formulas are derived for perturbation growth coefficients; the effects of the twisting of the fluid, environment, velocity discontinuities, layer thickness, density ratios, and other factors on stability are analyzed qualitatively and quantitatively. An instability criterion is derived in general form for annular jets propagating in a medium.