# doubt on meshing a cylinder

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 July 22, 2005, 12:55 doubt on meshing a cylinder #1 FELIX JOE S Guest   Posts: n/a Sir, I am a student learning fluent in IIT Chennai. I had a problem in meshing a cylinder of 0.004m(outer diameter) and 0.0037m(inner diameter) [i.e. thickness of 0.0003m ] and a height of 0.02m height. So the problem is that the meshing error(in the Gambit) is occuring .I used all the three basic volume meshes. The error is that " SIGSEGV (segmentation violaton) error" . All occurs for the mesh size of 0.0001 . please suggest me ways to solve it. thanking you JOE

 July 22, 2005, 13:06 EXPLAIN ME ABOUT AN ERROR #2 MANIVANNAN Guest   Posts: n/a Sir, I am a student learning fluent in IIT Chennai. I had a problem in axis symmetric valve the problem is in fluent which says divergence detected in AMG solver: X momentum the inlet we give as total gauge pressure & outlet is pressure which is 0. please suggest me ways to solve it. thanking you

 July 22, 2005, 13:31 Re: EXPLAIN ME ABOUT AN ERROR #3 AJG Guest   Posts: n/a I think u are using to many nodes! the density is to high for your server. Try a more coarse mesh.

 July 23, 2005, 00:31 Re: doubt on meshing a cylinder #4 Mahesh Guest   Posts: n/a create a cylindet of 4 & 3.7 as dimensions. in Fluent, say grid is created in mm. So it will take new dimensions as 0.004 & 0.0037

 July 23, 2005, 02:21 Re: doubt on meshing a cylinder #5 Mehdi Ghoddosy Guest   Posts: n/a Dear Felix: What meshing scheme are you using? I think using Map scheme can help you. However if you decet you meshing scheme i can give you more offers. Best Regards

 July 23, 2005, 05:15 Re: EXPLAIN ME ABOUT AN ERROR #6 Swarup Guest   Posts: n/a Check your problem set-up, especially your boundary condition values. I hope you understand what is meant by divergence. your variable values are going out of bounds. Are you getting some messages before divergence detection message is thrown? Swarup.

 July 23, 2005, 11:47 Re: doubt on meshing a cylinder #7 sharuk Guest   Posts: n/a use size function

 July 25, 2005, 07:36 Re:Re: doubt on meshing a cylinder #8 FELIX JOE S Guest   Posts: n/a Sir I have tried it doing that also but the error is in the mesh of that length to thickness ratio (as i think). The mesh scheme i used predominently was TET/HYBRID still i also used Hex Map. I also modeled it in mm still the same error is present.I still need the mesh size for both i.e. (1) if i model it in same size (2) if in scaled one but i have tried both of it. I still need more advice Thank you for your valued suggestions JOE

 July 25, 2005, 07:45 Re:Re: doubt on meshing a cylinder #9 FELIX JOE S Guest   Posts: n/a Sir I have tried it doing that also but the error is in the mesh of that length to thickness ratio (as i think). The mesh scheme i used predominently was TET/HYBRID still i also used Hex Map. I also modeled it in mm still the same error is present.I still need the mesh size for both i.e. (1) if i model it in same size (2) if in scaled one but i have tried both of it. I still need more advice Thank you for your valued suggestions JOE

 July 25, 2005, 08:04 Re: doubt on meshing a cylinder #10 Mehdi Ghoddosy Guest   Posts: n/a Dear Felix: I think your mesh and model sizes does not have any problem, and range in conventional geometries. Also, meshing cylenders is a conventional and frequently used case in CFD problems. So, the problem arises in creating geometry or meshing process. To avoid this, first forget your cylinder thickness and try to mesh remaining geometry. Fisrt, grade start and end caps(circles). Split them to four curves and try to mesh the cap surface using Map scheme. Then, grade the cylinder wall, and mesh it using Map scheme. Now, mesh the volume using Map or Cooper scheme. Following this concept no problem should be arised. If you got the error again, there is an error in your program, or concept of defining mesh or geometry. If no problem arised we would discuss about ramainnig part of your model. Good luck. Best Regards Mehdi Ghoddosy

 July 25, 2005, 08:08 Re: doubt on meshing a cylinder #11 Mehdi Ghoddosy Guest   Posts: n/a Dear Felix: Excuse me, forgot to say, create the geometry using down-top approach. Means that first create the circles and then wall surface, then compose the volume using these faces.

 July 26, 2005, 03:44 Re: EXPLAIN ME ABOUT AN ERROR #12 sharuk Guest   Posts: n/a this is for manivannan, check ur boundary conditions, and reduce the relaxation factors.if it doesn't work go for coupled/implicit solver.i'm in krishna hostel, room no 111, no. 9884204548, tell me if u got it correct. sharuk

 July 27, 2005, 04:06 Re:Re: doubt on meshing a cylinder #13 zxaar Guest   Posts: n/a why don't you try making mesh in mm and then scale it in fluent. if the problem coming from mesh dimensions. otherwise sigmentation violation suggest that there is a problem with your geomtery. check that.

 July 27, 2005, 08:06 Re:Re: doubt on meshing a cylinder #14 Mehdi Ghoddosy Guest   Posts: n/a Dear Felix: Excuse me, if I have not read your message carefully; but as I remember you said that tried to generate the mesh with dimension in mm and got the error again. However, if you have not tried to generate your mesh in mm, I recommend try it first. Regards Mehdi Ghoddosy

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