Reduction of the structure-acoustic problem using normal modes and lanczos vectors

The coupled structure-acoustic problem is studied using the finite element method. An efficient strategy for solving the coupled eigenvalue problem is proposed. The strategy uses a limited number of the uncoupled structural normal modes and acoustic fluid normal modes together with a set of interface-dependant Lanczos vectors for each domain to reduce the coupled problem. The Lanczos vectors are calculated by applying the vectors derived from the movement of the uncoupled modes of the interacting domain. For example, the pressure distribution of the fluid modes are used to generate the Lanczos vectors for the structural domain. This ends up in a very compact coupled eigenvalue problem to be solved. The method is investigated in a numerical example.