Notice of wall condition in cfx
 

Hello everyone. I am attempting to simulate an open channel flow in CFX using a free surface flow with water in the channel and air in the region above it. I have followed quite closely the tutorial of free surface flow over a bump to help me simulate this. During solving the CFX solver manager displays the following message:

| A wall has been placed at portion(s) of an OUTLET |
| boundary condition (at 60.9% of the faces, 77.0% of the area) |
| to prevent fluid from flowing into the domain. |
| The boundary condition name is: Outlet. |
| The fluid name is: Air. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead.

Can anyone please explain what this is and what it might be telling me is incorrect with this model.

Thanks very much and best wishes.
Tim