A COUPLED FE AND BOUNDARY INTEGRAL-EQUATION METHOD BASED ON EXTERIOR DOMAIN DECOMPOSITION FOR FLUID-STRUCTURE INTERFACE PROBLEMS

A coupled finite element and exterior domain decomposition-based bound ary integral formulations for the solutions of two- or three-dimension al time-harmonic fluid structure interaction problems is described in this paper. It is known that the memory limitation of computers has be en one of the major obstacles for solving large scale high frequency f luid structure interface systems using various existing nonlocal finit e element and boundary integral equation coupling techniques due to th e fully populated resultant matrix generated from the boundary integra l equation representation. The essence of this study is to decompose, through domain decomposition of the exterior region, the original exte rior problem into arbitrary subproblems with data sharing only at the interfaces. By decomposing the exterior infinite domain into an approp riate number of infinite subdomains, this method not only ensures the validity of the formulation for all frequencies but also leads to a di agonalized, blockwise-banded system of discretized equations. The size of an individual submatrix (i.e. a block) that is associated with an exterior subdomain may be decided by the user, and may be selected suc h that the restriction due to the memory limitation of a given compute r may be accommodated. In addition, the method is suited for parallel processing since the data associated with each subdomain (impedance ma trices, load vectors, etc.) may be generated in parallel, and the comm unication needed will be only for the interface values. Most significa ntly, unlike the existing coupled finite element and boundary integral equation techniques that are valid for all frequencies, our method av oids the use of both the hypersingular operator and the double integra ls, therefore reducing the computational complexity. Numerical experim ents have been performed for elastic cylindrical shells subjected to a plane incident wave. The results have demonstrated the accuracy of th e method for wavenumbers ranging from 0 to 30, both directly on the sh ell and in the far field, and have confirmed that the procedure is val id for all frequencies.