Calculation of acoustic radiation modes by using spherical waves and generalized singular value decomposition

Acoustic radiation modes (ARMs) have been widely used in noise control engineering owing to their convenient sound-power characteristics. However, the evaluation of ARMs for non-regular structures can be computationally intensive: it usually involves solving the boundary integral equation (BIE) by using the boundary element method in order to obtain the sound power radiation resistance matrix, followed by a singular value decomposition to obtain the radiation modes. The proposed procedure involves projecting spherical harmonics onto an enclosing surface, followed by the application of generalized singular value decomposition, with the result that the need to solve the BIE is eliminated, which potentially reduces the computational effort significantly.