Large-eddy simulation, convective instability, and modal causality of coaxial supersonic air–water jets considering a swirl effect

An annular liquid sheet sheared by a coaxial supersonic gas stream with swirling effect is investigated using Large Eddy Simulation. Despite its wide applications in aerospace and medical devices, the instability spatial characters have been barely due to high complexity under condition. Unlike conventional use of temporal dynamic mode decomposition (DMD), DMD applied axial direction evaluate transient convective instability. The high-velocity cases show significantly stronger nozzle near-field. However, has only marginal effects on In addition, proper orthogonal (POD) extracts essential topology velocity, momentum, pressure fields. Pulsatile flapping instabilities are observed flow, where flow demonstrates schrink/expansion as well instabilities. all POD modes field take form coherent wavepacket structures, their wavelength forms wavepackets dependent speed rather than swirling. Time coefficients leading momentum fields an interesting correlation. Hence, causal–effect relationship between these quantified via transfer entropy from information theory. generally higher vice versa, this trend enhanced low-velocity