[Gmsh] Interpolation Scheme for High Order Elements

John Pease Moore jpmoore4 at MIT.EDU
Tue May 20 00:22:05 CEST 2014

Hi GMSH developers,

I'm still trying to figure this out. Maybe I should try to explain my problem in a little more detail. Basically, I get a mesh from GMSH and then move the high-order nodes within each element such that they are more optimal than equi-spaced nodes (in particular, I am using the electrostatic nodes of Hesthaven).

I then write a GMSH file (attached) with these updated node placements, along with a custom interpolation scheme. I'm not sure exactly what GMSH does with this interpolation scheme after it reads it from the file, nor if I am defining the scheme properly.

When GMSH reads the file, it indicates that it has read the scheme, but the elements display the same way they would without the custom interpolation scheme (incorrectly, because GMSH assumes equally spaced nodes). So, my first question is does specifying the interpolation scheme in the file indicate that the elements should always be rendered with that scheme? Do I need to explicitly  tell GMSH to use the custom scheme somehow?

Or perhaps this functionality is only supported in post-processing views?

Secondly, it is possible to have a 'val-exp-matrix' of all zeros? The way I usually define my basis functions is such that values are represented by a basis function matrix that does not require the specification of the u,v,w location within each element. It appears that this case would correspond to an all zeros 'val-exp-matrix'. Is this correct?



From: John Pease Moore
Sent: Sunday, May 18, 2014 10:38 PM
To: gmsh at geuz.org
Subject: Interpolation Scheme for High Order Elements


I am trying to write a GMSH *.msh file in order to apply my own interpolation scheme for high order elements. I took a look at the reference manual, but I'm still having a few issues.

Does anyone have an example .msh file with a high order interpolation scheme defined they would be willing to send me? (for p > 1) It doesn't really matter what the element type is-- if you can send me an example I should be able to figure out the rest.

Any help at all would be awesome.

Thank you for your time,

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