Wave Envelope Elements for Acoustical Radiation in Inhomogeneous Media

This paper reviews applications of the wave envelope, finite element method to linear acoustical wave propagation. A detailed formulation is given for the particular case of acoustical radiation from a sound source embedded in a region of significant temperature variation. Results are presented for the case of sound propagating along a heated pipe and radiating from an unflanged exhaust. Measured and computed transmission losses are shown to be in close agreement. Although the formulation is presented in the context of acoustical propagation it applies equally well to other wave propagation problems which involve the solution of inhomogeneous, Helmholtz type equations. The analysis presented in this paper and all applications to date are for the axisymmetric case. © 1988.