Impedance
Use the Impedance condition to specify a normal specific impedance Zn on a boundary. Add this node from the Mechanical submenu. The boundary condition reads
The condition relates the normal stress at the boundary to the normal velocity, through the value if the specific impedance. The tangential velocity can optionally be constrained to zero.
Mechanical
Enter a value or expression for the Specific impedance Zn (SI unit: Pa⋅s/m).
Select a condition for the Tangential velocity — Slip (perfect) (the default) or No slip. The No Slip option will apply an additional constraint for the velocity in the tangential direction on the boundary. When Slip (perfect) is selected the impedance mimics the behavior of a corresponding pressure acoustics model with a normal impedance condition.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog.
Excluded Edges/Points
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog. See Suppressing Constraints on Lower Dimensions for details.