I am solving a coupled structural-acoustic calculation, and I want to find the most important "coupled modes", i.e. the modes which transfer the most energy between the structure and the fluid. One way to do this would be to solve the first N modes of the full generalized eigenproblem (Kx=Mx), and compute a measure of the coupling ( something like \pi = u'Sp ), where S is the coupling matrix, u is the displacement and p is there pressure. One could then sort the coupled modes according to \pi. However, important coupled modes which do not lie in the first "N" modes may not be found (unless there are matrix structuring results that I am not aware of).
Are there any algorithms that guarantee that find first N_c important coupled modes as defined by an user defined criterion, and are there any code s that implement them? The only reference I could find was Alan R. Tackett, Massimiliano Di Ventra, Targeting specific eigenvectors and eigenvalues of a given Hamiltonian using arbitrary selection criteria, PHYSICAL REVIEW B 66, 245104 2002. Sorry for the slightly OT discussion. Thanks, Nachiket
