Modelling and prediction of the peak-radiated sound in subsonic axisymmetric air jets using acoustic analogy-based asymptotic analysis

Mohammed Z. Afsar, Adrian Sescu, Stewart J. Leib

Research output: Contribution to journalArticlepeer-review


This paper uses asymptotic analysis within the generalized acoustic analogy formulation (Goldstein 2003 JFM488, 315–333. (doi:10.1017/S0022112003004890)) to develop a noise prediction model for the peak sound of axisymmetric round jets at subsonic acoustic Mach numbers (Ma). The analogy shows that the exact formula for the acoustic pressure is given by a convolution product of a propagator tensor (determined by the vector Green's function of the adjoint linearized Euler equations for a given jet mean flow) and a generalized source term representing the jet turbulence field. Using a low-frequency/small spread rate asymptotic expansion of the propagator, mean flow non-parallelism enters the lowest order Green's function solution via the streamwise component of the mean flow advection vector in a hyperbolic partial differential equation. We then address the predictive capability of the solution to this partial differential equation when used in the analogy through first-of-its-kind numerical calculations when an experimentally verified model of the turbulence source structure is used together with Reynolds-averaged Navier–Stokes solutions for the jet mean flow. Our noise predictions show a reasonable level of accuracy in the peak noise direction at Ma = 0.9, for Strouhal numbers up to about 0.6, and at Ma = 0.5 using modified source coefficients. Possible reasons for this are discussed. Moreover, the prediction range can be extended beyond unity Strouhal number by using an approximate composite asymptotic formula for the vector Green's function that reduces to the locally parallel flow limit at high frequencies.
Original languageEnglish
Article number20190073
Number of pages19
JournalProceedings of the Royal Society Part A - Mathematical, Physical and Engineering Sciences
Issue number2159
Early online date14 Oct 2019
Publication statusPublished - 2 Dec 2019


  • computational fluid dynamics
  • CFD
  • acoustic analogies
  • asymptotic methods
  • jet noise
  • aerospace


Dive into the research topics of 'Modelling and prediction of the peak-radiated sound in subsonic axisymmetric air jets using acoustic analogy-based asymptotic analysis'. Together they form a unique fingerprint.

Cite this