The Acoustic-Shell Interaction, Frequency Domain Interface
This physics interface requires a Structural Mechanics Module license. For theory and physics interface feature descriptions relating to the Shell interface, see the Structural Mechanics Module User’s Guide.
The Acoustic-Shell Interaction, Frequency Domain interface (), found under the Acoustics>Acoustic-Structure Interaction branch () when adding a physics interface, combines features from the Pressure Acoustics, Frequency Domain and Shell interfaces to connect the acoustics pressure variations in the fluid domain with the structural deformation of a shell boundary. It may for example be used for determining the transmission of sound through a thin elastic structure such as a car hood and analyzing the vibroacoustics of a loudspeaker cone.
Acoustic-structure interaction refers to a multiphysics phenomenon where the acoustic pressure causes a fluid load on the solid surface, and the structural acceleration acts on the fluid domain as a normal acceleration across the fluid-structure boundary.
Special physics interface conditions are readily defined at the fluid-shell boundary and set up the fluid loads on the shell boundary and the effect of the structural accelerations on the fluid. The physics interface is only available for 3D geometries, and it is capable of modeling the coupled pressure acoustics and shell vibrations in the frequency domain.
When a predefined Acoustic-Shell Interaction, Frequency Domain interface is added from the Acoustics>Acoustic-Structure Interaction branch of the Model Wizard or the Add Physics windows, the Pressure Acoustics, Frequency Domain and Shell interfaces are added to the Model Builder.
In addition, the Multiphysics node is added, which automatically includes the multiphysics coupling feature Acoustic-Structure Boundary.
On the Constituent Physics Interfaces
The Pressure Acoustics, Frequency Domain interface computes the pressure variations when modeling the propagation of acoustic waves in fluids at quiescent background conditions. The physics interface solves the Helmholtz equation and is suited for all linear frequency-domain acoustic simulations with harmonic variations of the pressure field. It includes domain conditions to model losses in a homogenized way, so-called fluid models for porous materials as well as losses in narrow regions. The domain features also include background incident acoustic fields.
The Shell interface is used to model structural shells on 3D faces. Shells are thin flat or curved structures, having significant bending stiffness. The physics interface uses shell elements of the MITC type, which can be used for analyzing both thin (Kirchhoff theory) and thick (Mindlin theory) shells. Geometric nonlinearity can be taken into account. The material is assumed to be linearly elastic.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined coupling features, for example Acoustic-Shell Interaction, Frequency Domain, the Selection on the coupling feature is automatically set to All boundaries. In this way the multiphysics coupling is automatically active on all Shell boundaries with Pressure Acoustics, Frequency Domain on one side or both sides.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if single Shell and Pressure Acoustics, Frequency Domain interfaces are added, COMSOL adds an empty Multiphysics node. You can choose the available coupling features, but you need manually to select on which boundaries they need to be applied, or select All boundaries to recover the predefined behavior.
Coupling features are available from the context menu (right-click the Multiphysics node) or from the Physics toolbar, Multiphysics menu.
Physics Interfaces and Coupling Features
Use the online help in COMSOL Multiphysics to locate and search all the documentation. All these links also work directly in COMSOL Multiphysics when using the Help system.
Coupling Feature
The Acoustic-Structure Boundary coupling feature is described in the Multiphysics Couplings chapter.
Physics Interface Features
Physics nodes are available from the Physics ribbon toolbar (Windows users), Physics context menu (Mac or Linux users), or right-click to access the context menu (all users).
In general, to add a node, go to the Physics toolbar, no matter what operating system you are using. Subnodes are available by clicking the parent node and selecting it from the Attributes menu.
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The available physics features for The Pressure Acoustics, Frequency Domain Interface are listed in the section Domain, Boundary, Edge, Point, and Pair Nodes for the Pressure Acoustics, Frequency Domain Interface.
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The available physics features for Results Evaluation are listed in the section Domain, Boundary, Edge, Point, and Pair Nodes for the Shell and Plate Interfaces in the Structural Mechanics Module User’s Guide
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Theory Background for the Pressure Acoustics Branch
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Theory for Shell and Plate Interfaces in the Structural Mechanics Module User’s Guide