[Gmsh] EXTERNAL: Re: Embedded Mesh

Max Orok morok at mevex.com
Thu Oct 11 21:02:31 CEST 2018


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. <Aaron.J.Jensen at leidos.com
> 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:cgeuzaine at uliege.be]
> Sent: Thursday, October 11, 2018 8:11 AM
> To: Jensen, Aaron J. [US-US]
> Cc: gmsh at onelab.info
> Subject: EXTERNAL: Re: [Gmsh] Embedded Mesh
>
>
>
> > On 10 Oct 2018, at 21:12, Jensen, Aaron J. <Aaron.J.Jensen at leidos.com>
> 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>_______________________________________________
> > gmsh mailing list
> > gmsh at onelab.info
> > http://onelab.info/mailman/listinfo/gmsh
>
>> 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
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