The Thermoviscous Acoustic-Structure Boundary coupling () is used to couple a Thermoviscous Acoustics model to any structural component. The feature couples to Solid Mechanics, Shell, Membrane, and Multibody Dynamics interfaces.

where ut,fluid is the total fluid velocity (including a background component if applicable) and usolid is the solid displacement. The first equation is in the frequency domain and the second in the time domain, respectively. This coupling results in the stress also being continuous across the boundary. The condition for the total temperature Tt can be set to either isothermal or adiabatic. In the case where a shell or membrane is interior to the thermoviscous acoustics domain, a slit is automatically applied to the pressure p and temperature T degrees of freedom (DOFs).

See Settings for further details about Label and Name.

The default Name (for the first multiphysics coupling feature in the model) is tsb1.

Select the Thermal condition that applies on the solid surface to be either Isothermal (the default selected) or Adiabatic.

These settings are shown when the Advanced Physics Options is selected. It controls how the constraints (continuity in displacement) are handled. Select either Study controlled (the default selected), Weak constraints, or Pointwise constraints.

When set to Study controlled, the weak constraints are automatically selected when an eigenfrequencies study is performed. This type of coupling is necessary as the eigenvalue (the angular frequency ω) enters the coupling expression. This will create extra variables at the boundary, so-called Lagrange multipliers, ensuring the correct behavior and solution. For a normal frequency domain study the pointwise constraint is selected. In the time domain there are no options and the weak formulation is always used.

This section defines the physics involved in the multiphysics coupling. The Thermoviscous Acoustics and Structure lists include all applicable physics interfaces. See Acoustic-Structure Boundary for details.