Parbolized Stability Analysis of Jets Issuing from Serrated Nozzles

Jets issuing from serrated nozzles have a correspondingly serrated time-averaged flow field. We solve the mildly non-parallel linear parabolized stability problem for such high speed turbulent jets to model the coherent wavepackets in the flow. The base flow for the analysis is the mean flow field from a large-eddy simulation database of a cold Mach 0.9 fully turbulent jet issuing from a nozzle with six serrations, a benchmark case in the literature. The fluctuation data is also filtered to extract the most-energetic coherent part using proper orthogonal decomposition. Such filtered data is shown to bear an encouraging resemblance with the predicted wavepackets.