> On 6 Apr 2019, at 22:22, Abiti Adili <[email protected]> wrote:
>
> Dear Dr. Geuzaine:
>
> I added the what you have suggested at the end of my geo file ( attached
> above). I have created, just for the sake of trial, a coarse mesh and saved
> the msh file ( attached above). I understand that my mesh now is periodic
> and there is the periodicity information at the end right after the element
> list in my msh file. The problem now is that I could not understand how to
> read this information. For example:
>
> 1) what is affine and the numbers after it mean?
It's the 4x4 matrix (by row) encoding the affine transformation between the
entities.
> 2) Are those two columned numbers are the vertices that correspond to
> periodic nodes on opposite sides? if yes, how do I read these information.?
>
From the documentation (MSH 4 file format):
```
$Periodic
numPeriodicLinks(size_t)
entityDim(int) entityTag(int) entityTagMaster(int)
numAffine(size_t) value(double) ...
numCorrespondingNodes(size_t)
nodeTag(size_t) nodeTagMaster(size_t)
...
...
$EndPeriodic
```
So the section provides, for each pair of geometrical entities (`entityTag` and
`entityMasterTag`) of dimension `entityDim`, the correspondance between
`numCorrespondingNodes` mesh nodes also given as pairs: a node tag (in entity
`entityTag`) and its corresponding master node (in entity `entityMasterTag`),
etc.
Christophe
> I would appreciate if you could explain this a little or direct me to where I
> can refer to when reading these information so that I can use them when
> imposing periodicity condition.
>
> Thank you very much.
>
> Adil
>
>
> ________________________________________
> From: Christophe Geuzaine <[email protected]>
> Sent: Friday, April 5, 2019 11:42:19 AM
> To: Abiti Adili
> Cc: [email protected]
> Subject: Re: [Gmsh] How can I make this mesh such that it has periodic sides
>
>
>
>> On 4 Apr 2019, at 18:03, Abiti Adili <[email protected]> wrote:
>>
>> I have a tetrahedral mesh over a unit box that has two balls of different
>> sizes inside the box. The geometry is created by geometrycloser.geo, and the
>> physical entities and such were created by importing geometrycloser.geo
>> into omnibuscloser.geo.
>>
>> I have a periodicity condition to impose where I need to say that
>> 1) right side of the box is the same with left side
>> 2) top side is the same with bottom side
>> 3) front side is the same with the back side
>>
>> When I tried to make the system matrices periodic using a function that has
>> been tested on other examples, it did not work correctly and I have
>> concluded that either vertices or facets on the sides of the box may not
>> have been aligned.
>>
>> I am writing to ask if there is anyway that I can modify the geo files I
>> provided so that I can integrate the periodicity condition into the mesh I
>> make? Thank you very much.
>>
>
> You need to explicitly tell Gmsh that the meshes should be periodic. In your
> example, add
>
> Periodic Surface{5} = {6} Translate {1,0,0};
> Periodic Surface{2} = {4} Translate {0,1,0};
> Periodic Surface{1} = {3} Translate {0,0,1};
>
> at the end of the geo file.
>
> Christophe
>
>>
>> Adil<geometrycloser.geo><omnibuscloser.geo>_______________________________________________
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> —
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> https://nam04.safelinks.protection.outlook.com/?url=http:%2F%2Fwww.montefiore.ulg.ac.be%2F~geuzaine&data=02%7C01%7Caadili1%40lsu.edu%7Cf6d0e23c90ae4902f21e08d6b9e5b272%7C2d4dad3f50ae47d983a09ae2b1f466f8%7C0%7C0%7C636900793555447951&sdata=H1pAr9A4hxxWXTxHDiYoXnUbxPfU95yhkoBlXBk6C4k%3D&reserved=0
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>
>
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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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