CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Open Source Meshers: Gmsh, Netgen, CGNS, ... (http://www.cfd-online.com/Forums/openfoam-meshing-open/)
-   -   Netgen mesh settings for STL geometries (http://www.cfd-online.com/Forums/openfoam-meshing-open/61954-netgen-mesh-settings-stl-geometries.html)

lucchini August 16, 2007 05:56

Hi all, I started using net
 
Hi all,

I started using netgen a couple of weeks ago and I found it a very powerful tool considering the high mesh quality it is able to provide for complex geometries.

I wonder if someone in this forum knows the meaning of the following settings in the Meshing Options - Mesh size window:

1) Elements per curvature radius
2) Elements per edge
3) STL - chart distance
4) STL - line length
5) STL/IGES/STEP - close edges
6) STL - surface curvature
7) STL - edge angle
8) STL - surface mesh curv

Any kind of help is very appreciated.

Thanks in advance

Tommaso

philippose August 16, 2007 14:26

Hello Tommaso, A good day t
 
Hello Tommaso,

A good day to you!

I have been using Netgen for over a year now, and I personally find it to be the best opensource mesher available, by a far call :-)! Nothing comes close to the robustness, ease of use, and bug-free operation of the program!!

However, as you have found out, documentation is not really the strong point of the program :-)! I have tried to contact Joachim Schoeberl with exactly the questions you have posted, but have not got a reply yet (and that was almost a year ago :-)!)

Anyway... off-late, I have started scouring the source-code of Netgen, first, to understand what each of those parameters mean, and then, to understand how it works, so that I can tweak it up.

For example, my idea is to try and implement a modified "Ruppert-Shewchuk" algorithm which I found in a paper, which overcomes one of the biggest problems of Netgen... its in-ability to control the mesh length scale at places where there are surfaces close to each other in a satisfactory manner.... it always ends up with just one layer of cells between the two surfaces, which ofcourse, is not good for CFD.

Now... so far I have only documented the functioning of the parameters in my head, but I think the time has come to try to make a document which explains the things I have (hopefully) understood. I hate documentation though!!

How quickly do you need answers to your query? Would it be ok, if I try to come up with a PDF, instead of trying to explain things here? It will take some time though :-)! I started typing it out here on the forum, but then cut-pasted it into a "tex" file.

Have a nice day!

Philippose

lucchini August 16, 2007 14:46

Hi Philippose, thanks for y
 
Hi Philippose,

thanks for your kind reply. A pdf file about netgen would be really helpful for lots of users. Take your time to do it, there is no hurry.

Thanks again,

bye

Tommaso

vikramanvikraman March 7, 2011 02:02

:) dear mr Philippose Rajan

i am vikraman i am trying to generate a volume mesh from an stl file
with netgen, initially it did once but it started crashing when completing about 99% of generation saying run time error i hav upgraded windows from 32 bit to 64 bit and have amd phenom quad core with 8gb ddr3 ram machine i have tried all my best even sent mail to
joachim no any reply from him
can you pls help and suggest how to over come the problem
thk u


All times are GMT -4. The time now is 21:23.