A method to calculate acoustic radiation modes based on spheroidal wave functions

Acoustic radiation modes (ARMs) have been widely used in noise control engineering. For an arbitrarily shaped radiator, ARMs are usually obtained by using the boundary element method (BEM). For high frequencies and large structures, the BEM calculation is usually time consuming. An alternative method was recently developed in which the ARMs are obtained by using generalized singular value decomposition and spherical harmonic functions. In this paper, spheroidal harmonic functions are used instead of spherical harmonic functions. The proposed method is potentially more efficient for ARM calculations for structures with one dimension significantly larger than the other two.