Examples of Standard Acoustics Problems These standard problems or scenarios occur frequently when analyzing acoustics: The Radiation Problem A vibrating structure (a speaker, for example) radiates sound into the surrounding space. A radiation boundary condition or perfectly matched layer (PML) is necessary to model the unbounded open domain. The Scattering Problem An incident wave impinges on a body and creates a scattered wave. A radiation boundary condition or PML is necessary. This could be a sonar application in underwater acoustics or an analysis of the scattered sound field around a human head. The Sound Field in an Interior Space The acoustic waves stay in a finite volume so no radiation condition is necessary. For example, this case represents the sound inside a room or a car interior. A more advanced example is the sound inside a transducer like a microphone; in this case, the acoustic field should be solved with the Thermoviscous Acoustics interface. Analysis using thermoviscous acoustics requires the Acoustics Module. Coupled Fluid-Elastic Structure Interaction (Structural Acoustics) If the radiating or scattering structure consists of an elastic material, the interaction must be considered between the body and the surrounding fluid. In the multiphysics coupling, the acoustic analysis provides a load (the sound pressure) to the structural analysis, and the structural analysis provides accelerations to the acoustic analysis. The Transmission Problem An incident sound wave propagates into a body, which can have different acoustic properties. Pressure and acceleration are continuous on the boundary. A typical transmission problem is that of modeling the behavior of mufflers. Aeroacoustics Problems The sound (noise) field is influenced by a background flow. This could be the propagating sound from a jet engine or the acoustic damping properties of a muffler with flow. Analysis of these types of problems requires the addition of the Acoustics Module. Poroelastic Waves Problem If the acoustic waves are propagating inside the saturating fluid of porous material, the detailed coupling between the fluid pressure and the solid displacement needs to be taken into account. In cases when only the fluid pressure is of interest, the porous material can be modeled using an equivalent fluid model. Analysis of this type of problem requires the addition of the Acoustics Module. Transducer Problems Transducers are devices for transformation of one form of energy to another (electrical, mechanical, or acoustical). This type of problem is common in acoustics and is a true multiphysics problem involving electric, structural, and acoustic interfaces. Typical problems of this type involve modeling loudspeakers, microphones, and piezo transducers. Analysis of these types of problems requires the addition of the Acoustics Module.