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Question for Meshing

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Question for Meshing

Posted by Markus Gruber at April 04. 2013

I am just doing serval modells for finite elemete simulation , i am just having some question for meshing.

Sometimes i am getting the Ng Exception at Surface meshing , the geometry is not always the same because the spheres in it will vary at radius and position(Look at the download link), so is there any way to some prefetching so that the mesher is able to mesh more modells. I think the problem is,if there a lot of spheres in it ,it's really hard to mesh it ,because it becomes more complex. At the moment the meshsize is not clear , because i have to some calculations if there is any accurancy problem. The size of block is 100x100x100 [nm] and spheres in it  vary in count and radius between 5 [nm] up to 20 [nm]

https://www.dropbox.com/s/jrwlytwlt5443zj/pic1.zip

 

One another question is , is there a big difference between GMSH and Netgen and how to use it

 

with best regards

 

Re: Question for Meshing

Posted by Markus Gruber at April 04. 2013

,at the moment i am using netgen , is there any way to improve the behaviour of the mesher or the modelle before meshing 

 

with best regards

Re: Question for Meshing

Posted by Christophe Bourcier at April 04. 2013

Hi,

To mesh shapes similar to yours I use NETGEN 1D-2D. It allows to mesh finer the spheres and coarser the box sides with a nice gradation.

You can use these parameters:

        algo_2d = Mesh.Triangle(algo=smesh.NETGEN_1D2D)
        algo_params = algo_2d.Parameters()
        algo_params.SetFineness( 4 )
        algo_params.SetMaxSize( average_length )
        algo_params.SetMinSize( min_length )

average_length will be the length of the segments on the straight edges.

min_length the minimal size of the segments on the arcs.

4 is for "very fine" in the dialog box.

For instance, on a box of side length 100, and spheres radius between 10 and 20, I use average_length=5 and min_length=1 and get good results.

If Netgen 1D-2D still fails on your shape, you may have a look at Distene's mesher BLSURF which is faster and robust than Netgen.

Christophe

Re: Question for Meshing

Posted by Markus Gruber at April 05. 2013

is there any way to say how much tetragons i want to have approximatly

Re: Question for Meshing

Posted by Saint Michael at April 05. 2013

"Evaluate" function is intended for this.

St.Michael

Re: Question for Meshing

Posted by Markus Gruber at April 06. 2013

This one ?

http://docs.salome-platform.org/salome_5_1_6/smesh/dev/interfaceSMESH_1_1SMESH__Gen.html#ae26663f2744633a399c1f9f0c80d8eee

 

Previously Saint Michael wrote:

"Evaluate" function is intended for this.

St.Michael

 

Re: Question for Meshing

Posted by Saint Michael at April 08. 2013

Yes

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