Two-dimensional acoustic wave propagation in elastic ducts

Integral transforms are employed in order to obtain a formal solution to the two-dimensional elastic-walled duct problem. The fluid inside the duct is stationary, inviscid and compressible, and is identical to the fluid outside the duct. A time-harmonic line source lies between the duct walls. With attention confined to the field inside the duct, an asymptotic analysis is implemented for high and low frequencies, yielding residues which are valid throughout the duct and branch-cut contributions which apply only in the far field.