An evaluation of linear instability waves as sources of sound in a supersonic turbulent jet

Kamran Mohseni, Tim Colonius, Jonathan B. Freund

Research output: Contribution to journalArticlepeer-review


Mach wave radiation from supersonic jets is revisited to better quantify the extent to which linearized equations represent the details of the actual mechanism. To this end, we solve the linearized Navier-Stokes equations (LNS) with precisely the same mean flow and inflow disturbances as a previous direct numerical simulation (DNS) of a perfectly expanded turbulent M = 1.92 jet [Freund et al., AIAA J. 38, 2023 (2000)]. We restrict our attention to the first two azimuthal modes, n = 0 and n = 1, which constitute most of the acoustic field. The direction of peak radiation and the peak Strouhal number matches the DNS reasonably well, which is in accord with previous experimental justification of the linear theory. However, it is found that the sound pressure level predicted by LNS is significantly lower than that from DNS. In order to investigate the discrepancy, individual frequency components of the solution are examined. These confirm that near the peak Strouhal number, particularly for the first helical mode n = 1, the amplification of disturbances in the LNS closely matches the DNS. However, away from the peak frequency (and generally for the azimuthal mode n = 0), modes in the LNS are damped while those in the DNS grow at rates comparable to those at the peak Strouhal number.

Original languageEnglish (US)
Pages (from-to)3593-3600
Number of pages8
JournalPhysics of fluids
Issue number10
StatePublished - Oct 2002
Externally publishedYes

ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


Dive into the research topics of 'An evaluation of linear instability waves as sources of sound in a supersonic turbulent jet'. Together they form a unique fingerprint.

Cite this