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-   -   Urgent help, help pl for meshing problem (http://www.cfd-online.com/Forums/fluent/49389-urgent-help-help-pl-meshing-problem.html)

 Shashi September 30, 2008 03:24

Urgent help, help pl for meshing problem

I want to mesh a piping which has got in bigining circular face, then these face turn into rectangular cum semi circular faces, lastly these faces turn into trangular face.how to mesh it, kindly advice

 chandra manik October 2, 2008 02:57

Re: Urgent help, help pl for meshing problem

Shasi, It does not matter what is the shape. I think your system is in 3D case. So anything for the shape is nothing to Gambit.

Meshing is the way to divide the geometry into small pieces where you can find the cells continously connectedt to other cells and this connection will maintain the shape of the geometry. Best meshing will bring the volume calculation based on meshing result compare to the geometry result has deviation is small is possible.

You can make the meshing very dense or very coarse, but to much coarse will bring bad result. For example i make the meshing of the circular face of pipe by first meshing the circular edge into 100 nodes and the meshing the face using tgrid or anytype so the result will more dense compare when i make circular edge meshing with only 10.

So meshing is not a problem, but when it is too coarse, the result will bad since the meshing can good enough maintain the initial volume geometry.

So you can meshing it as you can do, but you can consider the arts of the meshing, is it really can represent the initial geometry or the shape can be so funny?.

 shashi October 3, 2008 06:52

Re: Urgent help, help pl for meshing problem

Dear Manik Sir,I first united all the volumes. Then I selected Volume Mesh in Gambit. It meshed all the faces. I did it Default Meshing( Undetermed) with a space size 4. Since the faces I created carry complex shapes with small faces,still Gambit meshed all the faces. But when it initialised for Volume meshing, the operation failed after 8% repeatedly ,

there was no memory related error.

Thanks, my email shashi_vashisth@yahoo.com

 Veera Gutti October 3, 2008 14:59

Re: Urgent help, help pl for meshing problem

Can you please the console messages from GAMBIT, when you try to generate the volume mesh.

 shashi October 6, 2008 01:22

Re: Urgent help, help pl for meshing problem

The volume messe is progressing till 8 % thereafter it is terminating with "Perturbation error"

 Veera Gutti October 7, 2008 10:17

Re: Urgent help, help pl for meshing problem

Hi Shashi

Try meshing edges manually, so that you do not have large differences in the meshed element size for any adjacent elements.

Then while creating a volume mesh, use Element Type = Tet/Hybrid Type = Tgrid

 shashi October 8, 2008 07:35

Re: Urgent help, help pl for meshing problem

thanks, i used Type = Tet/Hybrid Type = Tgrid but while meshing the volume, the it says some of the space in corner is too small to mesh

 chandra manik October 8, 2008 09:41

Re: Urgent help, help pl for meshing problem

I am sorry miss this discussion please send me your file to chandr4_mnk@yahoo.com Before i also faced the petrubation message, it was about too much space or because large space in meshing.

 Veera Gutti October 8, 2008 11:24

Re: Urgent help, help pl for meshing problem

Hi shashi,

Try to mesh the edges (where automatic meshing is giving trouble) in your geometry manually. Make sure that you do not have large differences in the meshed element size for any corner of the adjacent edges. Once you have meshed the edges, then try to mesh the specific faces where you think problem occurred earlier while volume meshing. If the quality of that face mesh is satisfactory, then you can try the volume meshing using Tgrid.

Let me know if I am unclear.

If you still are facing problem while volume meshing, send me the gambit files to my email vr_gutti@yahoo.com, I will look into it.

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