Jet noise and jet-induced structural loads have become key issues in the design of commercial and military aircraft. Computational Fluid Dynamics (CFD) can be of use in predicting the underlying jet shear-layer instabilities and, in conjunction with classical acoustic theory, jet noise. The computational issues involved in the resolution of high Reynolds number unsteady jet flows are addressed in this paper. Once these jet flows can be accurately resolved, it should be possible to use acoustic theory to extract, for example, the far-field jet noise. An assessment of future work and computational resources required for directly computing far-field jet noise is also presented.
NOMENCLATURE
c speed of sound D jet diameter M Mach number (u/c) N total number of grid points p fluid pressure R 0 radial distance at which (u-u~)/(uc-u~)=l/2 (Ref. 19) Re Reynolds number (uD/v) St Strouhal number (fD/u) t time T,j Lighthill acoustic analogy instantaneous applied stress tensor u streamwise velocity component v radial velocity component x streamwise distance from jet exit y radial distance from jet center line 6,j Kronecker delta e viscous dissipation r/ Kolmogoroff dissipation length scale v molecular kinematic viscosity v, turbulent kinematic viscosity p fluid density z viscous stress tensor Superscripts mean component fluctuating component Subscripts c center line jet mean jet exit conditions oo far-field conditions