Stability of a capillary jet with linearly increasing axial velocity (with application to shaped charges)

The stability of a capillary jet of an ideal liquid with a linear variation of axial velocity is investigated. Because of the time dependence in the basic extensional flow the evolution of surface perturbations in the jet is an initial-value problem instead of an eigenvalue one (as in the case of non-stretching jets). The amplification of any given peturbation is found to depend on the elative effects of surface tension and intertia terms associated with the extensional flow as well as on the initial wavenumber and the specific time when the perturbation is introduced in the flow field. The simulation of a shaped-charge jet by the present model is discussed. The esults obtained are found to give a good description of the essential features of the breakup phenomenon of such jets.