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### Hello,How did the elmer find the boundary conditions?

Posted: 15 Dec 2021, 07:52
Dear friends，I use the two different conditions,i delete a lateral condition,but the result is so different,Result as the picture,the first's surface is the second's bed.i don't know why? Do you know? Thank you,brother!

Code: Select all

``````Boundary Condition 1
ComputeNormal = Logical False
Name = "sides1"
Target Boundaries(1) = 1
Flowdepth Skip = Logical True
End

Boundary Condition 2
ComputeNormal = Logical False
Name = "sides2"
Target Boundaries(1)  = 2
End

!! DON'T CHANGE ORDER OF NEXT 2 BC's!
!! They are automaticaly created in internal extrusion
!! bedrock:
Boundary Condition 3
ComputeNormal = Logical True
Name = "bedrock"
Flow Force BC = Logical True
Bottom Surface = Equals "bedrockDEM"
Bedrock = Logical True
!Height = 0.0
End

Boundary Condition 4
ComputeNormal = Logical False
Name = "surface"
Top Surface = Equals "surfaceDEM"

! Referred by: Exported Variable 2 Mask = ...
Surface = Logical True

Depth = Real 0.0
End``````

Code: Select all

``````Boundary Condition 1
ComputeNormal = Logical False
Name = "side"
Target Boundaries(1) = 1
Flowdepth Skip = Logical True
End

Boundary Condition 2
ComputeNormal = Logical True
Name = "bedrock"
Flow Force BC = Logical True
Bottom Surface = Equals "bedrockDEM"
Bedrock = Logical True
!Height = 0.0
End

Boundary Condition 3
ComputeNormal = Logical False
Name = "surface"
Top Surface = Equals "surfaceDEM"

! Referred by: Exported Variable 2 Mask = ...
Surface = Logical True

Depth = Real 0.0
End``````

### Re: Hello,How did the elmer find the boundary conditions?

Posted: 15 Dec 2021, 17:58
Hi

You're probably using internal extrusion to make the 3D mesh. This generates automatically the top and bottom surfaces using the 1st free indexes. So unfortunately you should now how many BCs are there in the mesh and give the next free indexes to that.

-Peter