Methods for simulating fluid-structure interaction and cavitation with existing finite element formulations

Techniques are presented for using existing options in production structural analysis finite element computer programs to simulate compressible fluid effects and fluid-structure interaction in piping system dynamics and multidimensional wave propagation. In piping system dynamics, the fluid is represented as a sequence of uniaxial tension-compressinal elements coupled to the pipe motion in the transverse direction, but free to move independently in the axial direction. To allow for the possibility of cavitation, a spring-mass element coupled in series to a gap is employed. For the calculation of wave propagation in multidimensional regions, it is shown how the elastic modulus and Poisson's ratio of typical structural elements can be chosen to yield the Hooke's law of a fluid. This, together with coupling conditions which force the fluid to move with a structure in the direction normal to their interface, but allow fluid slip in the tangential direction, makes possible the analysis of fluid-structure interaction as well. These techniques are applied to two simple fluid-structure systems to demonstrate their utility. 13 refs.