Modal analysis of fluid-structure interaction problems with pressure-based fluid finite elements for industrial applications

The present paper deals with numerical developments performed in the finite element code ANSYS in order to carry out coupled fluid-structure analysis with pressure-based formulation. As a result, enhancement of the modeling possibilities within ANSYS is carried out for the following fluid and fluid structure modes: i) fluid sloshing modes, ii) fluid and fluid-structure modes with pressure-displacement formulation in axi-symmetric geometry with non axi-symmetric loading, iii) fluid-structure modes with symmetric formulations for elasto-acoustic and hydro-elastic problems, using the so-called symmetric (u, p, phi) and (u, eta, phi) formulations. The paper also aims at providing finite element code users with test cases to refer to, for application of the new FSI formulations. The paper also serves as an introduction to the numerical calculation of eigenvalue problems with FSI. Theoretical bases of the formulations are first exposed; test-cases and industrial applications are then proposed. It is shown in particular that computing times are significantly decreased by using a symmetric formulation instead of a non-symmetric one, allowing modal analysis of complex structures with fluid coupling for industrial purposes.