Wavepackets in subsonic elliptical jets: coherent-structure eduction and linear modelling
Abstract
We study coherent structures extracted from time-resolved particle image velocimetry (TR-PIV) measurements of isothermal elliptical jets with aspect ratio of 1:2, at Mach numbers 0.4 and 0.7. The velocity snapshots are decomposed according to the D2 symmetry. Spectral proper orthogonal decomposition (SPOD) is then used to identify coherent structures. Modelling is performed using three-dimensional parabolised stability equations (3D-PSE) based on linearisation about the time-averaged mean flows. A comparison between SPOD and 3D-PSE results shows alignment of SPOD and single-mode PSE structures of up to 70\%. A linear combination of PSE solutions, obtained from the family of initially unstable local modes, leads to SPOD-PSE alignment of up to 90\%. Limitations are observed at low frequencies and near the nozzle and are attributed to the existence of non-modal amplification mechanisms. The study shows that coherent structures in turbulent elliptical jets can be educed using the D2-SPOD approach, and modelled using 3D PSE.
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BibTeX
@misc{amaral2026wavepackets,
title = {{Wavepackets in subsonic elliptical jets: coherent-structure eduction and linear modelling}},
author = {Filipe Ramos do Amaral and Mateus Peixoto Avanci and Jean-Christophe Robinet and Peter Jordan and Jérôme Huber and Grégoire Pont},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28221},
eprint = {2610.28221},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28221},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Wavepackets in subsonic elliptical jets: coherent-structure eduction and linear modelling
AU - Filipe Ramos do Amaral
AU - Mateus Peixoto Avanci
AU - Jean-Christophe Robinet
AU - Peter Jordan
AU - Jérôme Huber
AU - Grégoire Pont
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28221
UR - https://arxiv.org/abs/2610.28221
AB - We study coherent structures extracted from time-resolved particle image velocimetry (TR-PIV) measurements of isothermal elliptical jets with aspect ratio of 1:2, at Mach numbers 0.4 and 0.7. The velocity snapshots are decomposed according to the D_2 symmetry. Spectral proper orthogonal decomposition (SPOD) is then used to identify coherent structures. Modelling is performed using three-dimensional parabolised stability equations (3D-PSE) based on linearisation about the time-averaged mean flows. A comparison between SPOD and 3D-PSE results shows alignment of SPOD and single-mode PSE structures of up to 70\%. A linear combination of PSE solutions, obtained from the family of initially unstable local modes, leads to SPOD-PSE alignment of up to 90\%. Limitations are observed at low frequencies and near the nozzle and are attributed to the existence of non-modal amplification mechanisms. The study shows that coherent structures in turbulent elliptical jets can be educed using the D_2-SPOD approach, and modelled using 3D PSE.
ER -