The Thermoviscous 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 Thermoviscous Acoustic-Shell Interaction, Frequency Domain interface (), found under the Acoustics>Thermoviscous Acoustics branch () when adding a physics interface, combines the Thermoviscous Acoustics, Frequency Domain and Shell interfaces. The physics interface solves for and has a predefined coupling between the displacement field of the shell and the acoustic variations in the fluid domains. It can be used, for example, for modeling the vibrating response of micromirrors in MEMS applications. The physics interface is available for 3D geometries, and it is capable of modeling the coupled thermoviscous acoustics and shell vibrations in the frequency domain.
The physics interface solves the equations in the frequency domain assuming all fields and sources to be harmonic. Linear acoustics is assumed.
When a predefined Thermoviscous Acoustic-Shell Interaction, Frequency Domain interface is added from the Acoustics>Thermoviscous Acoustics branch of the Model Wizard or the Add Physics windows, the Thermoviscous 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 features Thermoviscous Acoustic-Structure Boundary. This feature automatically couples the thermoviscous acoustic domain to exterior shells (on exterior boundaries) and to interior shells (on interior boundaries).
For details about all the multiphysics couplings in the Acoustics Module, see Multiphysics Couplings.
On the Constituent Physics Interfaces
The Thermoviscous Acoustics, Frequency Domain interface is used to compute the acoustic variations of pressure, velocity, and temperature. The physics interface is required to accurately model acoustics in geometries of small dimensions. Near walls, viscosity and thermal conduction become important because it creates a viscous and a thermal boundary layer where losses are significant. For this reason, it is necessary to include thermal conduction effects and viscous losses explicitly in the governing equations.
The Shell interface is used to model structural shells on 3D boundaries. 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 are added using the predefined multiphysics interface, for example Thermoviscous 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 boundaries with Thermoviscous Acoustics, Frequency Domain on one side (exterior shells) or on both sides (interior shells) of Shell boundaries.
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 the single 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
See Thermoviscous Acoustic-Structure Boundary 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 Thermoviscous Acoustics, Frequency Domain Interface are listed in the section Domain, Boundary, and Pair Nodes for the Thermoviscous 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 Thermoviscous Acoustics Branch
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Theory for Shell and Plate Interfaces in the Structural Mechanics Module User’s Guide