[Gmsh] Conformal surfaces.

[I+D Magna Medic]

Thanks Dr. Matthias and Jean Pierre. 

I built the cubic body as you told me, extruding both surfaces. After
that I've built a physical body for the cubic one with those two bodies
created by the extrusion, _ _I expect that this will fuse them as only
one for the solver. 

Thank you for your advices. 

Félix Navarro Guirado | Físico Médico - Ingeniero
ingenieria at magnamedic.com 
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El 2015-10-07 12:57, Zenker, Dr. Matthias escribió: 

> Hi, 
> 
> „conformal" means that the mesh should be unique for interfaces between touching bodies. 
> 
> In order to achieve that, you need to make sure that no interface between bodies is duplicated. 
> 
> If you have a smaller surface on top of a larger one, you have to define the larger surface with the boundary line of the smaller one as a hole - that is what you did with surfaces 200 and 201. 
> 
> Then just define your rectangular volume using both surfaces. You don't need to make a compound or the like. 
> 
> HTH, 
> 
> Matthias 
> 
> VON: I+D Magna Medic [mailto:ingenieria at magnamedic.com] 
> GESENDET: Dienstag, 6. Oktober 2015 12:23
> AN: gmsh at geuz.org
> BETREFF: [Gmsh] Conformal surfaces. 
> 
> Dear gMeshers, 
> 
> I want to build three volumes as input mesh for my solver software (ELMER). In order to make the current flow I've been adviced to make the surfaces between them "conformal". 
> 
> The structure is very simple: a rectangular parallelepiped (30cm x 30 cm x 20 cm height) and two cilinders touching that body on the top and bottom faces. The cilinders act as electrodes (3mm height , 22 cm diameter). 
> 
> The only thing that I need to know is how to make the coincident surfaces "conformal". I think that this means that they should be exactly equal or maybe the same surface. 
> 
> My geo file looks like this: (for simplicity I'll detail the bottom cilinder only)
> 
> R = 0.11;
> 
> Point(1) = {-0.15, -0.15, -0.1, 0.1}; //Bottom face for parallelepiped
> Point(2) = {0.15, -0.15, -0.1, 0.1};
> Point(3) = {0.15, 0.15, -0.1, 0.1};
> Point(4) = {-0.15, 0.15, -0.1, 0.1};
> Line(1) = {3, 4};
> Line(2) = {4, 1}; 
> Line(3) = {1, 2};
> Line(4) = {2, 3};
> Line Loop(100) = {1, 2, 3, 4}; 
> 
> Point(5) = { 0, 0, -0.10, 0.1}; //Center for the base of the cilinder
> Point(6) = { R, 0, -0.10, 0.1};
> Point(7) = { 0, -R, -0.10, 0.1};
> Point(8) = {-R, 0, -0.10, 0.1};
> Point(9) = { 0, R, -0.10, 0.1};
> //Arcs
> Circle(5) = {6, 5, 7};
> Circle(6) = {7, 5, 8};
> Circle(7) = {8, 5, 9};
> Circle(8) = {9, 5, 6};
> Line Loop(101)= {5, 6, 7, 8}; 
> 
> Now I tried several strategies without good results. 
> 
> If I make a compound surface, the new one is different than the base of the cilinder, let me explain: 
> 
> Plane Surface (200) = {100, 101};
> Plane Surface (201) = {101}; 
> Compound Surface (203) = {200, 201}; 
> 
> The mesh generated by the surface 203 is quite different from those generated by 200 or 201. Then I tried: 
> 
> boundMaster[] = Boundary{Surface{203};};
> boundSlave[] = Boundary{Surface{201};};
> Periodic Surface 201 {boundSlave[]} = 203 {boundMaster[]}; 
> 
> But this throws an error because boundMaster is empty, this surprised me. And if I try to select boundaries by hand gMSH throws "Impossible to take boundaries of entity 203 (of type 307)". 
> 
> My second trial was: 
> 
> Plane Surface (200) = {100}; //Base of the parallelepiped
> Plane Surface (201) = {101}; //Base of the cilinder 
> 
> boundMaster[] = Boundary{Surface{200};};
> boundSlave[] = Boundary{Surface{201};};
> Periodic Surface 201 {boundSlave[]} = 200 {boundMaster[]}; 
> 
> This trows: (even if create circles "In Surface 200") 
> 
> Error : parallel planes do not intersect
> Error : parallel planes do not intersect
> Error : Only rotations or translations can currently be computed automatically for periodic faces: face 201 not meshed. 
> 
> What would you do? 
> 
> Thanks in advance, this is halting my work and any help would be appreciated. 
> 
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