Vibroacoustic Simulation of Partly Immersed Bodies by a Coupled Fast BE-FE Approach

Simulation of vibroacoustic behavior of submerged bodies necessitates dealing with fluid-structure coupled problems. In case of a high density of the fluid, the feedback of the acoustic pressure onto the structure cannot be neglected and a fully coupled system must be investigated. In this work, the finite element method (FEM) is used for the structural part. The commercial finite element package ANSYS is applied for setting up the mass and stiffness matrices. The boundary element method (BEM) is well suited for simulating the sound propagation in the unbounded exterior acoustic fluid domain. Here, the fast multipole method (FMM) is applied to overcome the known bottleneck of classical BE-methods. In the case of partly immersed bodies, Dirichlet boundary conditions on the fluid surface additionally have to be incorporated. This is done by applying a halfspace formulation. The extension of the FMM to this scenario is discussed. Iterative preconditioned solvers are employed and the numerical efficiency is discussed. The applicability of the coupling scheme is demonstrated using a realistic model problem.