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-   -   meshing suggestions (http://www.cfd-online.com/Forums/openfoam-meshing/105406-meshing-suggestions.html)

matt.mech.eng July 30, 2012 08:10

meshing suggestions
 
Hi all,

I wonder if anyone has any suggestions on how to generate a 2d mesh of quadrangles for the attached screenshot?

I want to generate a 2d mesh and extrude the profile along z-axis. I have been working for months trying to produce this mesh but have not succeeded in producing a mesh of high enough quality!

Any help would be greatly appreciated!!

jasimpson89 July 30, 2012 11:07

can't see any screen shot ??

matt.mech.eng July 30, 2012 19:44

2 Attachment(s)
sorry about that..

jasimpson89 July 31, 2012 04:26

Maybe try having a look at page 136 and 137 in the user guide. I haven't ever tried meshing an arc but this is where I might start. To then make it 2d look at collapsing some of the mesh points on top of each other (not entirely sure if that would work as I have never generated a 2d geometry) this is explained further on the blockMesh section

matt.mech.eng August 1, 2012 07:08

I want to generate a 3d mesh, but I have started with a 2d profile which would then be extruded. It is very easy to generate a mesh in this way using Salome.

The real problem is to break the geometry up in such a way as to minimize skewness and non-orthogonal cell faces..

anon_a August 1, 2012 08:13

Not a meshing expert here, but what about something similar to the circle mesh?

Check here to see how the circle is done.
http://www.cfd-online.com/Forums/ope...tml#post179978

elvis August 1, 2012 08:23

Hi,

what about using http://pythonflu.wikidot.com/hybridflu it is the direct way to import mesh from Salome to OF and it does support more mesh types (better to use compared to ideasUnvToFoam)

anon_a August 1, 2012 09:42

Hey Elvis,

what are the advantages of hybridflu compared to ideasUnvToFoam?
I am looking for this information in the site you provided but have not found it yet.

elvis August 1, 2012 10:11

Hi anon_a,

if you search you will find people complain that the conversion of their mesh did fail via ideasUnvToFoam quite often, because the ideasUnvToFoam converter does not convert all types of mesh that you can produce with salome.

http://www.openfoamworkshop.org/6th_...ord_slides.pdf
=> take a look at Slide 18 "Meshing" to understand the benefit I want to point at

anon_a August 1, 2012 10:16

Very interesting, thanks!
By the way, do you also have any pointers about how to produce polyhedral elements in SALOME?
So far I have been experimenting with polyDualMesh only.

matt.mech.eng August 1, 2012 19:39

Hi all,

anon_a- I have looked at breaking the geometry up in this way the problem is that I am using bubbleFoam (with modified k-eps model) and I need to have alpha initialised so that alpha equals 1 (ie 100% gas phase) at above height of 0.8m and 0 below this line.
I need to have a region of good refinement around the interface for stability.. and because of this constraint it makes using this method a bit trickier as the mesh tends to become more skewed which also seems to have a big effect on stabilty.

elvis- I have had a look at the link you provided bubbleFoam is not included. In terms of salome and polyhedral cells do you have any pointers? Could you please also specify exactly which cell types ideasUnvToFoam can handle?

Thanks for the help!

matt.mech.eng August 1, 2012 20:39

can pythonFlu/hybridFlu be used with OF2.1.1 and salome 6.4?

elvis August 2, 2012 02:23

Hi anon_a,

I am absolutly no expert with Salome. I saw an interesseting Post from Tobias Holzmann
pointing http://www.salome-platform.org/user-...edf-exercise-1 to this exercise that I want to go through when I have enough time.

http://www.salome-platform.org/user-section => visit the TUI section and the Tutorials section should give a good impression.

Quote:

salome and polyhedral cells
http://www.salome-platform.org/forum..._938#983021615
Support of polygonal/polyhedral mesh elements and quadratic meshes both in SMESH and VISU; =>
http://www.salome-platform.org/forum..._572#381680501

elvis August 2, 2012 02:30

Hi,

visit the pythonflu help forum http://sourceforge.net/projects/pyth.../forum/1364822 and ask

Quote:

can pythonFlu/hybridFlu be used with OF2.1.1 and salome 6.4?
I am quite sure that it does, if you compile from the sources
(I installed Pythonflu from sources for OF1.6-extend on a aptosid(=debian-based) distribution), so I can not confirm for the OF release you ask.
But Salome should not be the showstopper.

http://pythonflu.wikidot.com/install-sources is not the nicest install manual, if it helps I could post a "nice" install manual (i am biased) for a debian-based distribution


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