[Gmsh] High-order polynomial hybrid meshes

[Christophe Geuzaine]

> On 12 Jul 2019, at 10:32, Alejandro Pineiro Lema <alejandro.pineiro at upc.edu> wrote:
> 
> Dear users and programmers of Gmsh 
> 
> I am writing you in order to know if you could solve a small problem that I am struggling with. In my case, I am a PhD student who is trying to create an hybrid mesh to solve a Navier-Stokes problem.
> 
> I created some 2D and 3D geometries and high order meshes succesfully. However, now I would like to create a hybrid polynomial mesh, that is, a mesh where different elements can have a different polynomial approximation degree (and different number of nodes inside each element). 
> 
> As a example, imagine a 2D mesh where some of the elements are 1st order quadrilaterals and others could be 2nd order quadrilaterals and so on.
> 
> I have seen that Gmsh is able to change the order of elements for the whole mesh. So my question is: Is it only possible to change the order for the whole mesh?

Yes.

> Or is there any way to change the order for a specific element as well?

By design Gmsh generates conformal meshes (you would have hanging nodes if you were to change the order locally). But you could of course use (for example) the Gmsh API to post-process a conformal mesh and change the order locally afterwards.

Christophe

> 
> Thank you for taking your time to read this and I hope you can answer these questions.
> 
> Yours faithfully.
> 
> Alejandro Piñeiro-Lema
> 
> Msc Civil Engineer
> PhD student
> LaCàN-CIMNE-UPC Barcelona Tech
> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine