[Libmesh-users] Mesh issue in a system of equations

[Renato P. <re...@gm...>]

Hi

I am struggling here with boundary conditions in a system of equations.
I am solving a system for 3 vars: U,V,P (displacements and pressure).
I decoupled pressure and displacements as a first attempt (in fact, Kpp
gets to be an identity matrix), Fp is zero.

To test, I generated a mesh in CGAL and a similar one in GMSH.
I translate internally the CGAL mesh to libMesh.
For GMSH, I am using gmsh_io::read function.

It happens that, in CGAL translated mesh, when I set a boundary condition
in variable P, the solution for U and V gets invalid. The same does _not_
happen in the mesh generated in GMSH (works beautifully).

So, I believe the problem would be in the translation from CGAL to libMesh,
which is indeed very straightforward. I had already validated the
translation  for 2 variables (U,V). It looked fine.

Would you have an advice? What might be happening? In which case decoupled
variables might interact in the solver?

I am currently in a reverse engineering effort in the gmsh_io::read
function ... (no pain, no gain...)

Thanks,
Renato