[Gmsh] Postprocessing with QUAD4 Element

[Axel Gerstenberger]

Hi,

this is a question to the developers of Gmsh.

I'am using the QUAD4 element for postprocessing and I was wondering, if 
  real bilinear interpolation is used for displaying the results.

The attached figure should show a complete symmetric result with respect 
to the horizontal center of the mesh. This is true for the nodal values, 
but not for the interpolated areas. In fact, the QUAD4 elements appear 
to use 2 TRI3 elements to display the result. For the coarse academic 
example as shown in the attachment, I'd prefer to see a "perfect" 
symmetric result.

Could this behaviour be changed by user input or should it be changed in 
the Gmsh source? Unfortunatly, I am only experienced in FEM using 
Fortran and a little C#, but not C++, otherwise I would offer to help, 
if coding is needed.

Thanks for your suggestions and thanks for Gmsh,

Axel Gerstenberger

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