Acoustic Coupling between Structures and Enclosed Volumes of Fluid

This chapter discusses theoretical approaches that are applied to model and analyze coupled system behavior. The chapter introduces a simple one-dimensional illustration of the effects of interaction between a vibrating piston and fluid in a closed-ended tube. The free-vibration equations of strongly coupled structure-bounded fluid systems are not usually amenable to analytic solution in closed form, and numerical methods are commonly applied to such problems. Many vibroacoustic problems involve hundreds or thousands of interacting modes, and deterministic modeling and analysis is impracticable and economically unjustifiable. The most widely used probabilistic alternative is statistical energy analysis (SEA). The fundamental assumptions and principles of SEA are briefly explained in the chapter, and it is applied to a simple case of vibroacoustic coupling. The chapter discusses in detail the analysis of the propagation of coupled waves in a waveguide that consist of two parallel flat-plates enclosing a fluid, and a brief discussion of wave propagation in a fluid-filled elastic tube is provided.