To Whom It May Concern,

I am learning deal.ii to work on problems in solid mechanics. In the 
interest of computational efficiency, I plan to run most problems in 2D 
(plane stress assumption). Since the interesting problems I am concerned 
about require a non-trivial mesh, I learned how to use Gmsh based on the 
suggestion of Step-49.

With that in mind, I ran Step-44 in 2D and 3D (no change to the tutorials) 
and got results. I then used gmsh to generate a hypercube mesh in 2D and 
3D, modifying Step-44 using the Step-5 as a guide. While the 3D calculation 
with the imported mesh successfully converged, the 2D calculation with 
imported mesh did not converge. The 2D calculation failed with the residual 
from 10^5-10^16 (I tried multiple initial mesh densities).

Looking at the error output, it states that when a residual is large the 
matrix may be invertible or the wrong solver may be used. Since the only 
thing I changed was the origin of the mesh, I don't think either of these 
explanations should be the case.

As a sanity check, I ran a ~5 of the other tutorials with imported meshes. 
None of the other tutorials I tried ran into a similar issue when I 
imported a mesh from Gmsh. The issue also stuck around whether or not I 
used a structured or unstructured mesh, or changed the shape from a square 
to a rectangle.

Has anyone else ran into this issue? If so, how did you fix it?

Sincerely,
James Gorman

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