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, Layered 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 and the thermal condition) are handled. For the
Mechanical constraints type, select either
Study controlled (the default selected),
Weak constraints, or
Pointwise constraints. For the
Thermal constraint type, select either
Pointwise constraint (the default) or
Weak constraints. Finally, select the
Constraint method to apply to the pointwise constraints, either
Elemental (the default) or
Nodal.
When the Mechanical constraints type is 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 automatically selected. In the time domain there are no options, and the weak formulation is always used.