A least-squares spectral element method for sound propagation in acoustic ducts

This letter presents a novel numerical method and results for sound waves propagating in two-dimensional acoustic ducts without a flow. The method is based on a least-squares finite-element formulation to solve the two-dimensional Helmholtz equation with acoustic boundary conditions. Numerical calculations were obtained for sound waves propagating in an acoustically lined duct and in a rigid duct with a 90-deg bend. The exact solution and the boundary element solution of the acoustically lined duct were also obtained to validate the proposed numerical algorithm. Sound pressures computed by the present method agree very well with the exact and BEM solutions. (C) 1998 Acoustical Society of America. [S0001-4966(98)05511-8].