Simulation Error with Free Boundary Condition at the Outlet

System Modules TELEMAC-2D
1

I am running a Telemac-2D simulation for a channel confluence with 4 boundaries:

2 inflow boundaries where I’ve prescribed discharges (455),

1 outflow boundary with a known water level (544),

and 1 outflow boundary where I don’t have measured water level data.

To handle the unknown outflow, I attempted to assign a free boundary condition (444). However, the model fails to run and returns the following error:

GIVE A VELOCITY PROFILE

     IN THE BOUNDARY CONDITIONS FILE

     OR CHECK THE WATER DEPTHS.

     OTHER POSSIBLE CAUSE:

     SUPERCRITICAL ENTRY WITH FREE DEPTH

     IN THIS CASE GIVE A POSITIVE DEPTH

     IN THE INITIAL CONDITIONS

     OR PRESCRIBE THE DEPTH AT THE ENTRANCE.

My questions are:

What is the recommended way to assign boundary conditions in such a case with two outflows, one of which lacks measured data?

Is it acceptable to use 444 for the unknown outflow, and if so, how should I modify the initial conditions or boundary file to avoid the error?

Any guidance or examples from similar setups would be very helpful.

Thank You.

2

Hello [name removed], the message you’re getting suggests that ¨there’s no water at your boundary.

I don’t know much about 444 conditioning. I would suggest that you compute a normal rating curve at your boundary (using a [name removed] formula) and then impose it on your bondary.

You can also place your boundary far away from the area of interest to prevent any issues with your rating curve.

Hope this helps

1 Like
3

Thank you so much for your suggestion. In that case, can I use the Thompson boundary condition at that outlet since the depth at the outlet would be only suggestive, and the model can make adjustments based on the flow in the domain?