Transition from absolute to convective instability in a compound jet

Abstract

A spatiotemporal analysis is performed for an incompressible and inviscid compound jet moving in an unbounded inviscid static medium in this article. A detailed parametric study is carried out to explore the transition from absolute to convective instability for different operating conditions. The absolute and convective regions are shown through four plots: (i) inner density ratio (Qi) and Weber number (We), (ii) outer density ratio (Qo) and Weber number (We), (iii) surface tension ratio (σ) and Weber number (We) and (iv) radius ratio (λ) and Weber number (We). There exists a critical Weber number below which the compound jet becomes absolutely unstable and above which the compound jet becomes convectively unstable. The present results complement the existing results and give a complete theoretical understanding of the compound jets instability behavior.