No Slip
The No Slip node sets up a no-slip condition for the acoustic velocity fluctuations on a hard wall. Add this node from the Mechanical submenu. The condition reads ut = 0.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.
Excluded Edges/Points
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. See Suppressing Constraints on Lower Dimensions for details.
Mechanical and thermal boundary conditions contribute such that a condition can be set on the velocity and temperature simultaneously (they do not override). Thermal type condition override each other and the same is true for mechanical type conditions.