The Piezoelectric Effect, Time Explicit (
) is a multiphysics coupling feature between the
Elastic Waves, Time Explicit interface and the
Electrostatics interface used to model a piezoelectric material. It couples the
Piezoelectric Material node in elastic waves to the
Charge Conservation, Piezoelectric node in Electrostatics. The multiphysics coupling is automatically added when the
The Piezoelectric Waves, Time Explicit Interface is added as a new multiphysics interface.
See Settings for further details about
Label and
Name.
The default Name (for the first multiphysics coupling feature in the model) is
pzete1.
This section defines the physics involved in the multiphysics coupling. Only the Elastic Waves, Time Explicit and
Electrostatics physics interfaces can be selected.
The Piezoelectric Effect (
) is a multiphysics coupling feature between the
Solid Mechanics interface and the
Electrostatics interface used to model a piezoelectric material. This feature is used for the finite element method (FEM) based interfaces and is applicable for transient, frequency domain, and stationary studies. The
Piezoelectric Effect is described for
The Piezoelectricity Interface.
The Lorentz Coupling (
) is a multiphysics coupling feature between the
Magnetic Fields interface and the
Solid Mechanics interface. It passes the Lorentz force
F = J × B from the
Magnetic Fields interface to the
Solid Mechanics interface and, passes the induced electric field
E = v × B from the
Solid Mechanics interface to the
Magnetic Fields interface. The Lorentz force effect on a moving structure is similar to that of the Rayleigh alpha-damping, where the damping coefficient is proportional to the background magnetic field and the material electric conductivity.
The Lorentz force and induced electric field can also be added separately from the interfaces, for instance, by using the Body Load feature from the
Solid Mechanics interface and the
Velocity (Lorentz term) feature (in 2D and 2D axisymmetric) from the
Magnetic Fields interface. Once the
Lorentz Coupling feature is applied, those interface features with the same purpose should not be used to avoid double counting. When modeling electroacoustic transducers, like loudspeakers, the coupling is typically added in the voice coil domain.
The Lorentz Coupling feature is available in 2D, 2D axisymmetric, and 3D geometries and is allowed for both time-dependent and frequency-domain studies (including frequency domain perturbation and eigenfrequency studies). The coupling feature handles frames as well as the correct formulation for transient and frequency domain problems. For time-dependent studies, it only accounts for the Lorentz force contribution when the
Include geometric nonlinearity check box (in Study settings) is selected. When the displacement of the vibrating or moving part of the model cannot be neglected (when topology changes are important), the
Moving Mesh feature (added from the
Definitions) is usually used together with the
Lorentz Coupling feature.
The Acoustics Module includes several predefined multiphysics interfaces. When these interfaces are selected from the Model Wizard or the
Add Physics window both contributing physics and the multiphysics couplings are added to the
Model Builder. It is always possible to build a model sequentially adding one physics at the time and then coupling them. Note that far from all possible couplings are represented in the predefined physics interfaces. All the couplings are listed in the
Coupling Features section.
When physics interfaces are added using the predefined multiphysics interfaces, for example Thermoviscous Acoustic-Structure Interaction, the
Selection of the coupling feature, in this case the
Thermoviscous Acoustic-Structure Boundary, is automatically set to
All boundaries. In this way the multiphysics coupling is automatically active on all boundaries with
Thermoviscous Acoustics on one side and
Solid Mechanics on the other.
If physics interfaces are added one at a time, followed by the coupling features, the selections are not automatically set. For example, if the single interfaces are added, COMSOL Multiphysics adds an empty Multiphysics Couplings 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.
) can be used for modeling deformation of magnetically actuated structures, which includes interaction of magnetic fields with magnetic materials and current carrying elements such as coils and wires.