Modal recovery methods for solution of fluid-structure problems with rigid wall loads

Abstract A method is presented which enables the acoustic modes of a fluid to be recovered in an analysis based on rigid wall loads of a structure or portion of a structure. It is shown that the method leads to a structural solution which is identical to the coupled fluid-structure solution provided that the fluid is discretized sufficiently to retain the requisite spectral fidelity. An application of this method to the waterhammer response of a pipe segment is given, which in addition to validating the method, shows that the coupled response differs significantly from the structural behavior predicted by added mass, or incompressible, representations of the fluid. When the method is used to recapture fluid-structure interaction in a subsystem, silent boundaries are needed for the fluid domain. The method is also applicable to many other fluid-structure problems, and is particularly useful when the fluid loads are determined experimentally or by complex computational methods that are not readily coupled with structural models.