RuntimeError: Found overly constrained point while setting up constraints

Dear Pylith team,
I try to use SimpleDB to rewrite the boundary conditions in examples/3d/hex8/step04.cfg to apply non-uniform velocity boundary conditions that do not change with depth on +x, -x, +y, -y-faces.
First of all, I gave the velocity boundary condition on the + x and -x-faces, which did not cause any problems, and I got the result I want.
Then, I continued to give the velocity boundary condition on the + y and -y-faces, resulting in the following error.

The rewritten step04.cfg and spatialdb files are attached below:
step04.cfg (6.8 KB) (858 Bytes)
Thank you in advance.

You cannot constrain a degree of freedom with more than 1 boundary condition. If you constrain the x-dof with one BC then you cannot also constrain it with another boundary condition. If you want to constrain both the x and y degrees of freedom on the +x, -z, +y, and -y boundaries, then the boundary conditions cannot overlap on the edges.

Hi Brad,

Thank you for your fast response.
I tried to use two db files to assign the velocity boundary conditions to +x,-x-faces and + y,-y-faces, respectively, and they did not coincide on the edges, but I still got the same error.
How can I achieve this if I want to impose velocity boundary conditions on four boundary surfaces at the same time?


This error almost surely indicates that at least one point is associated with two boundary conditions constraining x and y degrees of freedom. Looking at your step04.cfg files, I think this is the only way that you can get that error. The only workaround is to make sure your nodesets that constrain both x and y degrees of freedom don’t share any vertices.

Dear Brad,

Thanks again, I get the point now.