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:

• 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},
  }

• 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},
  }