[Gmsh] Gmsh new boundary layer mesh operator

Christophe Geuzaine cgeuzaine at ulg.ac.be
Thu Apr 2 21:07:49 CEST 2015


> On 31 Mar 2015, at 13:29, Alexander Tismer <alexander.tismer at ihs.uni-stuttgart.de> wrote:
> 
> Hi Christophe,
> 
> thanks for your quick reply.
> But I'm sorry there was a mistake in my question and I'm not sure if I understand your answer. So I ask again.
> 
>> So my question: does the meshGRegion operator requests any mesh vertex reparametrization on its bounding faces of edges if using transfinite stuff?
> 
> I want to know:
> 
> Does the meshGRegion::operator() requests any mesh vertex reparametrization of its bounding faces OR edges if using transfinite stuff?
> 
> Maybe an example: Assume there is a cube. 12 Edges are meshed with
> 
>> GEdge::meshAttributes.method = MESH_TRANSFINITE
>> GEdge::meshAttributes.nbPointsTransfinite = 10;
>> GEdge::meshAttributes.typeTransfinite = 1;
>> GEdge::meshAttributes.coeffTransfinite = 1;
> 
> and 5 faces with
> 
>> GFace::meshAttributes.method = MESH_UNSTRUCTURED;
> 
> and 1 face with
> 
>> GFace::meshAttributes.method = MESH_TRANSFINITE;
> 
> Now I call the meshGRegion::operator() function. Question again: is there any call to a reparametrization function of any bounding geometrical surface in the meshGRegion::operator() function?

No, normally not directly in meshGRegion::operator(), unless you generate high-order meshes.

Christophe


> Because the surface mesh is moved, but the underlying geometrical surface definition doesn't change.
> 
> 
> Best regards
> Alex
> 
> On 03/31/2015 12:44 PM, Christophe Geuzaine wrote:
>>> On 31 Mar 2015, at 09:35, Alexander Tismer <alexander.tismer at ihs.uni-stuttgart.de> wrote:
>>> 
>>> Hello,
>>> 
>>> I write a mesh operator that starts from a surface mesh and adds a boundary layer to it (according to this paper http://onlinelibrary.wiley.com/doi/10.1002/1097-0207%2820000910/20%2949:1/2%3C193::AID-NME929%3E3.0.CO;2-R/abstract).
>>> 
>>> Steps are:
>>> 1) create surface mesh
>>> 2) calculate normals
>>> 3) move old GFaces
>>> 4) create elements in boundary layer (green elements)
>>> 5) mesh internal GRegion (orange elements)
>>> 
>>> My algorithm works fine. But if I mesh some bounding surfaces using transfinite edges and surfaces there occurs very very flat elements in the final internal GRegion.
>>> 
>>> So my question: does the meshGRegion operator requests any mesh vertex reparametrization on its bounding faces of edges if using transfinite stuff?
>>> 
>> Hi Alex - No; if you change the definition of surfaces, you will indeed want to reparametrize the mesh vertices so that the transfinite algorithm (which works in parametric coordinates) can compute the new vertices correctly.
>> 
>> 
>> 
>>> Please find attached a mesh cut of the final mesh.
>>> 
>>> Best regards
>>> Alex
>>> 
>>> 
>>>  -- 
>>> Alexander Tismer
>>> 
>>> Institut für Strömungsmechanik
>>> und Hydraulische Strömungsmaschinen
>>> Universität Stuttgart
>>> Pfaffenwaldring 10
>>> 70550 Stuttgart
>>> 
>>> Tel.:   +49 (0) 711 / 685 63007
>>> Fax:    +49 (0) 711 / 685 63255
>>> eMail:
>>> alexander.tismer at ihs.uni-stuttgart.de
>>> http://www.ihs.uni-stuttgart.de
>>> <mesh.png>_______________________________________________
>>> gmsh mailing list
>>> gmsh at geuz.org
>>> http://www.geuz.org/mailman/listinfo/gmsh
> 
> -- 
> Alexander Tismer
> 
> Institut für Strömungsmechanik
> und Hydraulische Strömungsmaschinen
> Universität Stuttgart
> Pfaffenwaldring 10
> 70550 Stuttgart
> 
> Tel.:   +49 (0) 711 / 685 63007
> Fax:    +49 (0) 711 / 685 63255
> eMail: alexander.tismer at ihs.uni-stuttgart.de
> http://www.ihs.uni-stuttgart.de
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine







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