The Acoustic–Piezoelectric Interaction, Transient Interface
The Acoustic–Piezoelectric Interaction, Transient multiphysics interface (), found when adding a physics interface under the Acoustics>Acoustic–Structure Interaction branch (), combines the Pressure Acoustics, Transient and Piezoelectricity interfaces to connect and solve for the acoustic pressure variations in fluids with the structural deformation in both solids and piezoelectric solid domains. The physics interface also includes features from Electrostatics to solve for the electric field in the piezoelectric material. Examples include modeling piezoelectric transducers for sonar or medical applications and, for example, enhancing the impedance matching layers.
The pressure wave equation is solved in the fluid domain and the structural dynamic equations in the solid together with the constitutive relationships required to model piezoelectrics. Both the direct and inverse piezoelectric effects can be modeled, and the piezoelectric coupling can be formulated using the strain-charge or stress-charge forms.
When a predefined Acoustic–Piezoelectric Interaction, Transient interface is added from the Acoustics>Acoustic–Structure Interaction branch of the Model Wizard or the Add Physics windows, the Pressure Acoustics, Frequency Domain, Solid Mechanics, and Electrostatics interfaces are added to the Model Builder.
In addition, the Multiphysics Couplings node is added, which automatically includes the Acoustic–Structure Boundary and Piezoelectricity multiphysics couplings.
See The Multiphysics Branch and Multiphysics Modeling Workflow in the COMSOL Multiphysics Reference Manual.
Settings for Physics Interfaces and Multiphysics Couplings
When the predefined multiphysics interface is used, the Selection on the Acoustic–Structure Boundary multiphysics coupling is automatically set to All boundaries. In this way, the multiphysics coupling is automatically active on all boundaries with Pressure Acoustics, Frequency Domain on one side and Solid Mechanics on the other. Similarly, the Selection on the Piezoelectricity multiphysics coupling is automatically set to All domains and active in all valid domains.
However, if physics interfaces are added one at a time, followed by the multiphysics couplings, these modified settings are not automatically included.
For example, if the single interfaces are added, COMSOL Multiphysics adds an empty Multiphysics Couplings node. You can choose the available multiphysics couplings, but you need manually to select on which boundaries or domains they need to be applied, or select All boundaries or All domains to recover the predefined behavior.
Multiphysics couplings are available from the context menu (right-click the Multiphysics Couplings node) or from the Physics toolbar, Multiphysics menu.
Physics Interfaces and Multiphysics Couplings
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.
Multiphysics Couplings
The Acoustic–Structure Boundary multiphysics coupling is described in the Multiphysics Couplings chapter. The Piezoelectricity multiphysics coupling is shortly described in The Piezoelectricity Interface.
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, Transient Interface are listed in the section Domain, Boundary, Edge, and Point Nodes for the Pressure Acoustics, Transient Interface.
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The available physics features for The Solid Mechanics Interface are listed in the Structural Mechanics Module User’s Guide.
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The available physics features for The Electrostatics Interface are listed in the section Domain, Boundary, Edge, Point, and Pair Nodes for the Electrostatics Interface in the COMSOL Multiphysics Reference Manual.
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Some additional piezoelectric features for the Solid Mechanics and Electrostatics interfaces are described for The Piezoelectricity Interface.
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Theory section in the Structural Mechanics Module User’s Guide
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Theory of Electrostatics in the COMSOL Multiphysics Reference Manual
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Theory Background for the Pressure Acoustics Branch