A Timeline of Jet Instability Research
A chronological and topological review of past and recent progress in the analysis of jet instability
Editor
Lutz Lesshafft
Nonlinear global modes in hot jets (2006)
LUTZ LESSHAFFT, PATRICK HUERRE, PIERRE SAGAUT, MARC TERRACOL
This paper demonstrates that the self-sustained oscillations in hot jets are caused by the underlying absolute instability (for the latter, see Monkewitz & Sohn 1988 and Lesshafft & Huerre 2007). The same has of course been inferred already by Sreenivasan et al. 1989 and by Monkewitz et al. 1990, but here we have a much higher quantitative confidence in the comparison between numerical simulation data and linear analysis. The principal argument is that the onset of self-sustained behaviour coincides with the onset of absolute instability, and that the frequency of vortex formation is well predicted by the absolute frequency, at least near the critical parameters.
I personally prefer the follow-up paper, Lesshafft, Huerre & Sagaut (Phys. Fluids 2007), which covers a larger range of parameters.
The present paper has sometimes wrongly been cited as showing linear global modes. Instead, it uses the notion of nonlinear global modes (Huerre & Monkewitz 1990, and several papers by Chomaz in the 1990s), which remains entirely based on local analysis. Linear global modes in jets were first presented by Nichols & Lele (JFM 2011) for supersonic settings, where all modes are stable. Unstable linear global modes were first shown by Coenen et al. (JFM 2017) for cases of low-density subsonic jets.
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