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This paper uses asymptotic analysis within the generalized acoustic analogyformulation (Goldstein. J. Fluid Mech 488, pp. 315-333, 2003) to develop anoise prediction model for the peak sound of axisymmetric round jets atsubsonic acoustic Mach numbers ($Ma$). The analogy shows that the exact formulafor the acoustic pressure is given by a convolution product of a propagatortensor (determined by the vector Green's function of the adjoint linearizedEuler equations for a given jet mean flow) and a generalized source termrepresenting the jet turbulence field.  Using a low frequency/small spread rate asymptotic expansion of thepropagator, mean flow non-parallelism enters the lowest order Green's functionsolution via the streamwise component of the mean flow advection vector in ahyperbolic partial differential equation (PDE). We then address the predictivecapability of the solution to this PDE when used in the analogy throughfirst-of-its-kind numerical calculations when an experimentally-verified modelof the turbulence source structure is used together with Reynolds-averagedNavier Stokes solutions for the jet mean flow. Our noise predictions show areasonable level of accuracy in the peak noise direction at $Ma=0.9$, forStrouhal number up to about $0.6$, and at $Ma=0.5$ using modified sourcecoefficients. Possible reasons for this are discussed. Moreover, the predictionrange can be extended beyond unity Strouhal number by using an approximatecomposite asymptotic formula for the vector Green's function that reduces tothe locally parallel flow limit at high frequencies.

Modeling and prediction of the peak radiated sound in sub-sonic axisymmetric air jets using acoustic analogy based asymptotic analysis