Waves in thin-walled fluid-filled ducts with arbitrary cross-sections

First, a variational formulation for fluid–shell coupling is presented. Subsequently new waveguide finite elements for fluid and fluid–shell coupling are derived from this formulation. Together with previously derived elements, modelling thin-walled shells, equations for pipes and ducts with arbitrary cross-sections may be formulated. Two examples, one pipe and one duct, are presented together with dispersion curves for the respective case.