Fluid-Structure Finite Element Vibrational Analysis

Abstract

A liquid finite element formulation which includes the potential energy due to compression but neglects the density change has been developed. Both kinetic and potential energy are expressed as functions of nodal displacements. Thus, the formulation is similar to that used for structural elements, with the only differences being that 1) the fluid can possess gravitational potential, and 2) the constitutive equations for fluid contain no Shear coefficients. Using this approach, structural and fluid elements can be used interchangeably in existing efficient sparse matrix structural computer programs such as SPAR. The theoretical development of the element formulations and the relationships of the local and global coordinates are shown. Solutions of fluid slosh, liquid compressibility, and coupled fluid-shell oscillation problems which were completed using a temporary digital computer program are shown. The frequency correlation of the solutions with classical theory is excellent.