The preferred mode of incompressible jets: linear frequency response analysis

By X. Garnaud, Lutz Lesshafft, Peter J. Schmid, P. Huerre. Journal of Fluid Mechanics, 2013

188 citations recorded by the source corpus.

Abstract The linear amplification of axisymmetric external forcing in incompressible jet flows is investigated within a fully non-parallel framework. Experimental and numerical studies have shown that isothermal jets preferably amplify external perturbations for Strouhal numbers in the range $0. 25\leq {\mathit{St}}_{D} \leq 0. 5$ , depending on the operating conditions. In the present study, the optimal forcing of an incompressible jet is computed as a function of the excitation frequency. This analysis characterizes the preferred amplification as a pseudo-resonance with a dominant Strouhal number of around $0. 45$ . The flow response at this frequency takes the form of a vortical wavepacket that peaks inside the potential core. Its global structure is characterized by the cooperation of local shear-layer and jet-column modes.

Subfields: Aerospace Engineering, Computational Mechanics

View Paper: https://www.semanticscholar.org/paper/467f37acdfeff98d6baed94f8d7c3c1ef3126ff3

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Citations in the corpus

Wavepackets and trapped acoustic modes in a turbulent jet: coherent structure eduction and global stability (2017, background): “Recent studies based on the resolvent operator (Garnaud et al. 2013b; Jeun et al. 2016; Semeraro et al. 2016; Tissot et al. 2017; Qadri & Schmid 2017) furthermore showed that, due to the non-normal nature of the operator, the K-H instability can be forced efficiently through the Orr-mechanism.”
Conditions for validity of mean flow stability analysis (2016, unknown): “…link between a local stability analysis and the dominant optimal response also justifies the argument that when a convective instability mechanism of a flow is strong, then the dominant optimal forcing φ1 will produce a particularly energetic response (see Garnaud et al. 2013; Sipp & Marquet 2013).”
Stability, Receptivity, and Sensitivity Analyses of Buffeting Transonic Flow over a Profile (2015, methodology): “A similar approach has already been used to describe pseudoresonances in a channel-flow configuration [44], turbulent pipe flow [45], Blasius boundary layer [46], and jets [47].”
Spectral proper orthogonal decomposition and its relationship to dynamic mode decomposition and resolvent analysis (2017, background): “Several authors have computed resolvent modes for jets in recent years (Garnaud et al., 2013; Jeun et al., 2016; Semeraro et al., 2016a ,b; Schmidt et al., 2017b) and their properties have been shown to predict certain properties of the jet.”