[Gmsh] adaptive mesh background field

[Christophe Geuzaine]

> On 2 Jul 2019, at 16:28, walter.steffe at alice.it wrote:
> 
>  Good morning,
> 
>  The tutorial t7.geo reports an example in which the mesh density is defined in a view consisting of scalar triangles.
>  This kind data structure does not enforce the continuity of the scalar field over adjacent triangles. 
>  But if the mesh is isotropic and conformal its density should be a continuous scalar field.
>  So, to me, it seems more natural (and more efficient) to define the mesh density in a view (or a pos file) consisting of scalar points.
> 
>  Would it be OK to use such kind of view as a background mesh ?
> 

Not just as points, because we need to interpolate the field in between the points. But you could indeed use a post-processing view based on a standard mesh to avoid duplicating data at the nodes. Note that in Gmsh this means that you will need 2 models, as associating the background field data to the mesh of one model means that you would destroy it if you remesh that same model.

Here is an example of doing just that (2 models: one for the bg mesh field, the other for the actual mesh) using the Gmsh API: https://gitlab.onelab.info/gmsh/gmsh/blob/master/demos/api/adapt_mesh.py

Christophe


>  Thanks
>  Walter  Steffè
>   
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine