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Patch Type ‘Patch’ not Constraint Type ‘Empty’


Simulation setup error: patch type ‘patch’ not constraint type ‘empty’

What happened?

  • The simulation setup has an error. Boundary condition of type ‘2D Empty’ was incorrectly used.


The ‘2D Empty’ type can only be used for a ‘2D Mesh’. Please note that SimScale platform supports 3D mesh generation only. 2D meshes cannot be generated, but can be uploaded via Mesh Upload option (for details see Upload Mesh ).

What could be the possible reason?

1- You were attempting a 3D simulation (with a 3D mesh), but a ‘Custom’ boundary condition with type ‘2D Empty’ was specified for a flow variable.

2- You were attempting a 2D simulation by applying ‘2D Empty’ boundary condition but with a 3D mesh.

3- You are attempting a 2D simulation with an uploaded 2D mesh, but either the ‘2D Empty’ boundary condition is incorrectly used or the mesh used does not satisfy 2D criterion according to OpenFOAM standards.

What can I do now?

1- For a 3D simulation, check your ‘Custom’ type boundary condition(s) and make sure ‘2D Empty’ is not assigned to any flow variable.

2- For a ‘2D simulation’ you will have to Upload a ‘2D mesh’. Or you can do a ‘pseudo 2D’ simulation with a 3D mesh by applying a ‘Symmetry’ type boundary condition for the faces in the 3rd-dimension.

3- For the uploaded 2D mesh, please make sure that there is only 1 cell in the 3rd- dimension to satisfy a true 2D mesh condition and the base ‘patch types’ for the 3rd-dimension faces are set to type ‘empty’ in the mesh ‘boundary’ file ( found in folder ‘constant/polyMesh’ of the OpenFOAM case setup ). Then in the simulation setup, make sure the ‘2D Empty’ boundary condition is applied to the corresponding 3rd-dimension faces.


For a ‘Case Upload‘: Please make sure that the constant/polyMesh/boundary file is consistent with the boundary condition files in ‘0’ (zero) folder e.g p , U, etc.


If none of the above suggestions did solve your problem, then please post the issue on our forum or contact us.

Last updated: October 2nd, 2020