Linear Acoustics 1: Duct

This benchmark problem may be considered as waves traveling through a duct. Although a smooth solution is expected over the entire frequency range, the numerical solution may be unstable if modes perpendicular to the traveling waves occur.

This benchmark can be used to study the eigenvalue problem with arbitrary admittance boundary conditions, discusses the accuracy of mode superposition for reconstruction of the solution in frequency domain, as well as study the convergence of your formulation towards h- and p-refinement.

A detailed description with references can be found in the PDF.