8 - Introduction to Numerically Based Analyses of Fluid-Structure Interaction

Abstract

The chapter discusses the vibration fields in solid structures and sound fields in fluids with the aim of providing tools for the vibroacoustic analysis of systems in which the two forms of field are coupled. The analysis of vibrations in structures and sound fields in closed or nearly closed volumes is most commonly accomplished by using finite element analysis (FEA). In FEA, the structure or fluid space are theoretically divided into contiguous elements of linear dimension that are substantially smaller than a structural or acoustic wavelength at the highest frequency of interest. It is also possible to apply finite difference analysis (FDA) to sound fields. The main practical problem with FDA in application to sound fields in volumes of arbitrary geometry is that it does not readily accommodate boundaries that do not conform to the grid line pattern. In addition, it is much more sensitive to local errors of field representation than FEA. The evaluation of the acoustic field generated by a vibrating surface in an infinitely extended volume of fluid is commonly accomplished by the application of boundary element analysis (BEA) to the evaluation of the field on the surface of radiator, through the approximate solution of the Kirchhoff–Helmholtz integral.