The Interior Wall node adds a wall boundary condition on interior boundaries. It is similar to the Wall boundary condition available on exterior boundaries except that it applies on both sides of an interior boundary. It allows discontinuities of the dependent variables across the boundary. The Interior Wall node specifies no gas flux for the gas phase.

Select a Liquid boundary condition — No slip (the default) or Slip.

No slip is the default boundary condition for the liquid. A no slip wall is a wall where the liquid velocity relative to the wall velocity is zero. For interior stationary walls, it sets the liquid velocity to zero on both sides of the wall:

For turbulent bubbly flows, the no slip condition may either be prescribed exactly or modeled using automatic wall treatment or wall functions depending on the Wall Treatment setting in the Turbulence section of the interface settings.

The Slip condition prescribes a no-penetration condition. For an interior stationary wall it sets the velocity component normal to the interior wall to zero on both sides of the wall:

The Translational velocity setting controls the translational velocity, utr. The list is per default set to Automatic from frame. When Automatic from frame is selected, the physics automatically detects if the spatial frame moves. If there is no movement, utr is set to 0. If the frame moves, utr becomes equal to the frame movement. utr is accounted for in the actual boundary condition prescribed in the Liquid boundary condition section.

When Manual is selected from Translational velocity selection list, the Velocity of moving wall, utr can be prescribed manually. Specifying the translational velocity manually does not automatically cause the associated wall to move. An additional Moving Mesh interface needs to be added to physically track the wall movement in the spatial reference frame.

This section is displayed by clicking the Show More Options button () and selecting Advanced Physics Options.