SOLVED – “overlapping boundaries for the 2D Area”

[alister.hood]

I’m posting this for future reference, as I have seen similar problems before and been unable to solve them.

I was getting this error even though according to the attribute table in RAS Mapper the two boundary conditions were correctly connected to “Perimeter 2”, not “Perimeter 1”:

Error with 2D Boundary Condition
There are overlapping boundaries
for the 2D Area:  Perimeter 1
for the boundaries:
downstream RG2
upstream RG2
This is not allowed in RAS
Please adjust the length of the boundary lines

Error starting unsteady simulation - Stopping compute process

I think there is a bug with something along the lines of renaming things, or creating things with the same names as things that have been deleted. Unfortunately I last worked on the project quite some time ago, so can’t remember enough to figure out exactly what.

Inspecting the unsteady flow file I found that there were duplicate entries for these boundary conditions, one identifying them with Perimeter 1, and the other with Perimeter 2.
I then tried renaming the boundary conditions in the geometry editor to see what would happen, and the model ran fine.
Checking the unsteady flow file all of the entries had been renamed, which seems like a bug itself.
I then tried renaming the boundary conditions back to the original names, and the model still ran fine…

[alister.hood]

Actually, it seems something funny happened, and either somehow what I thought happened with the unsteady flow file didn’t, or it somehow got overwritten afterwards.
I also played around running with a geometry where I deleted Perimeter 1, and for some reason it deleted all the Perimeter 1 BCs from the unsteady flow file. Going back to the original geometry I had to set up the Perimeter 1 boundary conditions again, and then it worked. Make a backup if you’re troubleshooting an issue like this!

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