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Wavepackets and trapped acoustic modes in turbulent jets

Coherent features of a turbulent Mach 0.9, Reynolds number 1M jet are educed from a high-fidelity large eddy simulation. Besides the well-known Kelvin-Helmholtz instabilities of the shear-layer, a new class of trapped acoustic waves is identified in the potential core. In two parallel studies, we investigate these trapped acoustic waves using different techniques.

The video shows a trapped acoustic mode in the potential core of a Mach 0.9 turbulent jet obtained from a global stability analysis of the mean flow.

Literature:

  • [PDF] [DOI] Schmidt, O. T., A. Towne, T. Colonius, A. V. G. Cavalieri, P. Jordan, and G. A. Brès. “Wavepackets and trapped acoustic modes in a turbulent jet: coherent structure eduction and global stability.” Journal of fluid mechanics 825 (2017): 1153-1181.
    [Bibtex] 
    @Article{SchmidtEtAl_2017_JFM,
author = {Schmidt, O. T. and Towne, A. and Colonius, T. and Cavalieri, A. V. G. and Jordan, P. and Br{\`e}s, G. A.},
title = {Wavepackets and trapped acoustic modes in a turbulent jet: coherent structure eduction and global stability},
journal = {Journal of Fluid Mechanics},
year = {2017},
volume = {825},
pages = {1153-1181},
doi = {10.1017/jfm.2017.407},
file = {:SchmidtEtAl_2017_JFM.pdf:PDF},
publisher = {Cambridge University Press},
}
  • [PDF] [DOI] Towne, A., A. V. G. Cavalieri, P. Jordan, T. Colonius, O. T. Schmidt, V. Jaunet, and G. A. Brès. “Acoustic resonance in the potential core of subsonic jets.” Journal of fluid mechanics 825 (2017): 1113-1152.
    [Bibtex] 
    @Article{TowneEtAl_2017_JFM,
author = {Towne, A. and Cavalieri, A. V. G. and Jordan, P. and Colonius, T. and Schmidt, O. T. and Jaunet, V. and Br{\`e}s, G. A.},
title = {Acoustic resonance in the potential core of subsonic jets},
journal = {Journal of Fluid Mechanics},
year = {2017},
volume = {825},
pages = {1113-1152},
doi = {10.1017/jfm.2017.346},
file = {:TowneEtAl_2017_JFM.pdf:PDF},
publisher = {Cambridge University Press},
}
Paper, , , ,

Stability, Receptivity and Transition of Compressible Corner Flows

The corner flow problem is a generic model for wing-fuselage intersections, rotor-hub junctions, and supersonic engine inlets. Corner flows have been subject to more than six decades of extensive study, in particular because of their importance to the aeronautical industry.

Our research focuses on the stability and transition of compressible corner flows using direct numerical simulation and linear theory. The key contributions to the understanding of corner flows are a detailed study of the effect of compressibility on their stability that lead to the discovery of a new modal instability mechanism at supersonic speeds, and an in-depth investigation of a non-modal mechanism that explains the flow’s sensitivity and early transition. The relevance of this mechanism became apparent in the first direct numerical simulations of laminar-turbulent transition in corner flows.

The video shows a direct numerical simulation of the symmetric transition scenario in terms of isosurfaces of the Lambda2 vortex criterion.

Literature:

  • [PDF] [DOI] Schmidt, O. T. and U. Rist. “Linear stability of compressible flow in a streamwise corner.” Journal of fluid mechanics 688 (2011): 569-590.
    [Bibtex] 
    @Article{SchmidtRist_2011_JFM,
Title = {Linear stability of compressible flow in a streamwise corner},
Author = {Schmidt, O. T. and Rist, U.},
Journal = {Journal of Fluid Mechanics},
Year = {2011},
Pages = {569-590},
Volume = {688},
Doi = {10.1017/jfm.2011.405},
File = {:./SchmidtRist_2011_JFM.pdf:PDF},
Publisher = {Cambridge Univ Press}
}
  • [PDF] [DOI] Schmidt, O. T., B. Selent, and U. Rist. “Direct numerical simulation of boundary layer transition in streamwise corner-flow.” High performance computing in science and engineering (2013): 337-348.
    [Bibtex] 
    @Article{SchmidtRistSelent_2013_HPCSE,
author = {Schmidt, O. T. and Selent, B. and Rist, U.},
title = {Direct numerical simulation of boundary layer transition in streamwise corner-flow},
journal = {High Performance Computing in Science and Engineering},
year = {2013},
pages = {337-348},
doi = {10.1017/S0022112095003284},
file = {:SchmidtRistSelent_2013_HPCSE.pdf:PDF},
owner = {iagoschm},
publisher = {Cambridge Univ Press},
}
  • [PDF] [DOI] Schmidt, O. T. and U. Rist. “Viscid–inviscid pseudo-resonance in streamwise corner flow.” Journal of fluid mechanics 743 (2014): 327–357.
    [Bibtex] 
    @Article{SchmidtRist_2014_JFM,
author = {Schmidt, O. T. and Rist, U.},
title = {Viscid--inviscid pseudo-resonance in streamwise corner flow},
journal = {Journal of Fluid Mechanics},
year = {2014},
volume = {743},
pages = {327--357},
doi = {10.1017/jfm.2014.31},
file = {:SchmidtRist_2014_JFM.pdf:PDF},
publisher = {Cambridge Univ Press},
}
  • [PDF] [DOI] Schmidt, O. T., S. M. Hosseini, Ulrich Rist, A. Hanifi, and D. S. Henningson. “Optimal wavepackets in streamwise corner flow.” Journal of fluid mechanics 766 (2015): 405–435.
    [Bibtex] 
    @Article{SchmidtEtAl_2015_JFM,
Title = {Optimal wavepackets in streamwise corner flow},
Author = {Schmidt, O. T. and Hosseini, S. M. and Rist, Ulrich and Hanifi, A. and Henningson, D. S.},
Journal = {Journal of Fluid Mechanics},
Year = {2015},
Pages = {405--435},
Volume = {766},
Doi = {10.1017/jfm.2015.18},
File = {:SchmidtEtAl_2015_JFM.pdf:PDF},
Publisher = {Cambridge Univ Press}
}
Paper, , , , ,