Yes, that did the trick. I used your idea in many different tests that I have done and basically added the second of the following two lines and that seemed to do the trick. Thank you! ... Plane Surface(1) = {1}; Physical Surface(2) = {1}; ------------------ Francis Poulin Associate Dean, Undergraduate Studies Associate Professor Department of Applied Mathematics University of Waterloo email: fpoulin@uwaterloo.ca Web: https://uwaterloo.ca/poulin-research-group/ Telephone: +1 519 888 4567 x32637 ________________________________ From: firedrake-bounces@imperial.ac.uk <firedrake-bounces@imperial.ac.uk> on behalf of G. D. McBain <gdmcbain@protonmail.com> Sent: Thursday, November 2, 2017 8:07:51 PM To: firedrake@imperial.ac.uk Subject: Re: [firedrake] problems with importing a mesh 2) For splines, I have also removed the point (updated code below) and when I look at it using gmsh I see that some points aren't actually on the boundary. This does seem odd but I am not sure how to fix it. Should I use a different kind of spline? The problem may be this: the Gmsh concept of Physical versus Elementary entities. http://gmsh.info/doc/texinfo/gmsh.html#Elementary-vs-physical-entities Your Gmsh file has only Elementary entities (Point, Line/Spline, Line Loop, Plane Surface). The trick is to mark the domain (for this two-dimensional problem) as a Physical Surface and each part of the boundary as a Physical Line. In three dimensions, those would be Physical Volume and Physical Surface, respectively. When a Gmsh file has no Physical entities, Gmsh puts everything into the mesh, including construction points (centres of arcs, control-points of splines), which often end up as disconnected, but if there is a least one Physical entity, only those finite elements belonging to Physical entities are included in the output .msh. A quirk of Firedrake, maybe inherited from PETSc which I think it uses to read Gmsh meshes, is that every part of the boundary has to be declared as part of a Physical Line/Surface, even if it's only going to get homogeneous natural boundary conditions in the finite element problem. Hope this helps; I can supply a little example, if the above is unclear.