The Thermoviscous Acoustic-Solid Interaction, Frequency Domain Interface
The Thermoviscous Acoustic-Solid Interaction, Frequency Domain interface (), found under the Thermoviscous Acoustics branch () when adding a physics interface, combines the Thermoviscous Acoustics, Frequency Domain and Solid Mechanics interfaces. The physics interface solves for, and has predefined couplings between, the displacement field in the solid and the acoustic variations in the fluid domains.
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-Solid 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 Solid Mechanics interfaces are added to the Model Builder.
In addition, the Multiphysics node is added, which automatically includes the multiphysics coupling feature Thermoviscous Acoustic-Structure Boundary.
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 Solid Mechanics interface is intended for general structural analysis of 3D, 2D or 2D axisymmetric bodies. The physics interface is based on solving Navier's equations, and results such as displacements, stresses, and strains are computed.
Settings for Physics Interfaces and Coupling Features
When physics are added using the predefined multiphysics interface, for example Thermoviscous Acoustic-Solid 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 and Solid Mechanics on the other.
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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Theory Background for the Thermoviscous Acoustics Branch
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Regarding the available structural-mechanics features and their theory background, see The Solid Mechanics Interface.