BEM and FEM analysis of fluid–structure interaction in a double tank

In this paper we present a fluid–structure interaction analysis of shell structures with compartments partially filled with a liquid. The compound shell was a simplified model of a fuel tank. The shell is considered to be thin and Kirghoff–Lave linear theory hypotheses are applied. The liquid is ideal and incompressible. Its properties and the filling levels may be different in each compartment. The shell vibrations coupled with liquid sloshing under the force of gravity were considered. The shell and sloshing modes were analysed simultaneously. The coupled problem is solved using a coupled BEM and FEM in-house solver. The tank structure is modeled by FEM and the liquid sloshing in the fluid domain is described by BEM. The method relies on determining the fluid pressure from the system of singular integral equations. For its numerical solution, the boundary element method was applied. The boundary of the liquid computational domain is discretized by nine-node boundary elements. The quadratic interpolation of functions and linear interpolation of flux are involved. The natural frequencies were obtained for the cylindrical double tank with two compartments.