Hi Max,

Thanks for the quick response.  I’m not sure how much time you have for 
debugging but I’ve attached my input files.  The main file is the geo file of 
course.  Goal.png shows what I have so far and what I am trying to do.  I have 
no error messages with the attached files but it’s only meshing the line loop 
and I would like it to fill in the surface with a 2D mesh.  Any thoughts?

Thanks,
Aaron

From: Max Orok [mailto:[email protected]]
Sent: Thursday, October 11, 2018 3:03 PM
To: Jensen, Aaron J. [US-US]; [email protected]
Subject: Re: [Gmsh] EXTERNAL: Re: Embedded Mesh

Hi Aaron,

I might be mistaken, but it looks like your in-file Line Loop stuff is good.
That might mean the Surface Loop command is giving the warning because the two 
Line Loops don't match up (i.e. form a closed surface)?

Sincerely,
Max

On Thu, Oct 11, 2018 at 1:25 PM, Jensen, Aaron J. 
<[email protected]<mailto:[email protected]>> wrote:
Christophe,

Thank you for the fast response.  The latest snapshot works great and fixes the 
crash.

I am still setting up the problem incorrectly.  Here is what I have now:


Merge "square";
Line Loop(1) = {1};

squareWidth = 1.5;
halfSquareWidth = squareWidth/2.0;

lc = 0.3;
Point(1001) = {-halfSquareWidth,-halfSquareWidth,0.0,lc};
Point(1002) = {-halfSquareWidth, halfSquareWidth,0.0,lc};
Point(1003) = { halfSquareWidth, halfSquareWidth,0.0,lc};
Point(1004) = { halfSquareWidth,-halfSquareWidth,0.0,lc};
Line(1001) = {1004,1003};
Line(1002) = {1003,1002};
Line(1003) = {1002,1001};
Line(1004) = {1001,1004};

Line Loop(1005) = {1002,1003,1004,1001};

Surface Loop(1006) = {1005, 1};


I think it is close to working but I get the warning message: "1D mesh not 
forming a closed loop".

Any help would be greatly appreciated.

Thanks,
Aaron

-----Original Message-----
From: Christophe Geuzaine 
[mailto:[email protected]<mailto:[email protected]>]
Sent: Thursday, October 11, 2018 8:11 AM
To: Jensen, Aaron J. [US-US]
Cc: [email protected]<mailto:[email protected]>
Subject: EXTERNAL: Re: [Gmsh] Embedded Mesh



> On 10 Oct 2018, at 21:12, Jensen, Aaron J. 
> <[email protected]<mailto:[email protected]>> wrote:
>
> Hello,
>
> I would like to merge an existing mesh into a geometry and then mesh the 
> unmeshed region using gmsh (something like a boundary mesh around a 
> pre-existing mesh generated externally by another program).  Ideally, this 
> would result in a mesh that was partially created in gmsh and partially 
> created externally to gmsh.  Ultimately, I would like to do this in both 2D 
> and 3D but am starting with the following in 2D:
>
>
>
> Merge "square";
>
> SetFactory("OpenCASCADE");
>
> Surface Loop(1) = {1};
> //sExternal = news;
> //Rectangle(sExternal) = {0, 0, 0.0, 0.5, 0.5};
>
> s1 = news;
> Rectangle(s1) = {-0.25, -0.25, 0.0, 1.0, 1.0};
>
> //BooleanDifference (2000) = { Surface{s1}; Delete; }{ Surface{sExternal}; };
> BooleanDifference (2000) = { Surface{s1}; Delete; }{ Surface{1}; };
>

This cannot work: boolean operations can only be applied to CAD entities. It 
should not crash though - and it does not on my machine. Can you try with the 
latest snapshot?

You can still produce a mesh like the one you want. With the built-in engine, 
simply

- load the mesh, which should contain the bounding surface mesh

- define the exterior "Surface Loop" where the interior surfaces are the 
bounding surfaces (discrete)

Christophe


>
>
> OpenCascade doesn’t recognize surface 1 and BooleanDifference causes gmsh to 
> crash.  I assume I am doing something wrong?  Can gmsh embed an existing mesh 
> into a gmsh geometry or CAD model?
>
> Thanks,
> Aaron
> <square>_______________________________________________
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—
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine

Free software: http://gmsh.info | http://getdp.info | http://onelab.info

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--
Max Orok
Contractor
www.mevex.com<http://www.mevex.com>

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Attachment: CombinedMesh.geo
Description: CombinedMesh.geo

Attachment: square
Description: square

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