[Gmsh] How to select Pre/Post processing entity by location?

[andrew]

I am glad it helped a bit.

For extrusion hints you can see the tutorial of openfoam and gmsh
https://openfoamwiki.net/index.php/2D_Mesh_Tutorial_using_GMSH
It gives some info for the extrusion vectors.

If you change the function in my files you can create functions for a few
elementary geometrical entities. Unfortunately selecting elements according
to geometry is a bit tricky in gmsh.
You can get the elements in an array and sweep in the array. This way you
can select the elements according to their coordinates with any criteria
you like.

For example in my file it goes

For PlaneFilter_jj In {0:#PlaneFilter_Surfaces[]-1}          <------- SWEEP
SURFACES
  PlaneFilter_n[]=PointsOf{Surface{PlaneFilter_Surfaces[PlaneFilter_jj]};};
    <----------- GET ALL POINTS OF SURFACE
  PlaneFilter_nn=#PlaneFilter_n[];
  PlaneFilter_cc=0;
  For PlaneFilter_kk In {0:#PlaneFilter_n[]-1}      <--------- SWEEP POINTS
IN SURFACE
    PlaneFilter_pn[]=Point{PlaneFilter_n[PlaneFilter_kk]};
 PlaneFilter_px=PlaneFilter_pn[0];          <------- COORDINATES
 PlaneFilter_py=PlaneFilter_pn[1];
 PlaneFilter_pz=PlaneFilter_pn[2];
.......

the two nested loops are for getting the points and their coordinates.
After that you can filter them any way you like...




2017-12-13 16:40 GMT+02:00 Shamsul Arefin <mail.shanto at gmail.com>:

> This is a nice trick. Thanks Andrew.
>
> However, this is only for selecting plane surfaces. I may have to tweak
> the code for Cylindrical Surfaces and also for more control over the shape
> of the geometry.
>
> # It would have been better if I could know how entities are stored in an
> array. Say I extrude a surface to create a block. If this extrusion command
> is saved in an array, what would be the sequence of IDs in the array, of
> generated surfaces of the block.
>
> ​
> Regards,
> Shamsul Arefin
> ph: 017655441319
>
> On Tue 12 Dec 3:46:59 pm, andrew <armitatz at gmail.com> wrote:
> I thought it was together with the other files !
>
>
>
> 2017-12-12 11:43 GMT+02:00 Shamsul Arefin <mail.shanto at gmail.com>:
>
>> Is there no other selection by location option? Say I want to select the
>> areas at 'z=0', or volumes between -10<x<+10 and -10<y<+10.
>>
>> The purpose is to select nodes from a particular geometric entity and
>> define name for those nodes i.e. a nodal set.
>>
>> Usually when I know the ID of a surface (for example), i can define a
>> "physical surface" and get the nodes and elements in the output-file
>> grouped together. Problem is, I would not know surface ID's while working
>> in the batch.
>>
>> Or anyone has a better idea for doing this with gmsh?
>>
>> ​
>> Regards,
>> Shamsul Arefin
>> ph: 017655441319
>>
>> On Mon 11 Dec 8:26:36 pm, andrew <armitatz at gmail.com> wrote:
>> ​perhaps this could help you. It selects a face that belongs to a plane
>>
>> ​
>>
>>
>> 2017-12-11 18:28 GMT+02:00 Shamsul Arefin <mail.shanto at gmail.com>:
>>
>>> Hello,
>>>
>>> Lets say I have a box modeled in gmsh. I want to select different faces
>>> of the box just by - selection through location coordinate. So far have not
>>> find anything in the documentation! Can anyone help?
>>>
>>> ​
>>> Regards,
>>> Shamsul Arefin
>>> ph: 017655441319
>>>
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>>> gmsh at onelab.info
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>>>
>>>
>>
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