THE LINEAR STABILITY OF A TWO-PHASE COMPOUND JET

摘要

A compound jet, whether viscous or inviscid, is unstable due to capillarity. The difference between the temporal and the spatial instabilities lies in the origin of the disturbance. If the instability is initiated by a disturbance in the initial condition, the situation is one of temporal instability and if the disturbances originate from a localized spatial source, the instability is spatial, with the latter being more appropriate for jet problems. At very high jet velocities, viscous effects are negligible; the disturbances grow spatially, but there is no dispersion and the results of all four analyses agree. At velocities below a critical value which is a function of the jet parameters the jet becomes absolutely unstable and this critical cutoff depends on the jet parameters, including the viscosities.