# [ANSYS Meshing] Problem with meshing a complex Geometry (Hex)

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 October 22, 2012, 14:50 Problem with meshing a complex Geometry (Hex) #1 New Member   Pete Drum Join Date: Sep 2012 Posts: 6 Rep Power: 12 Hi everyone, I just started to work with CFD Fluent and have a few Problems now with the meshing. I have to do a windenergypotential analysis for a building on my College campus. The Task is to make sort of a tutorial for other people, so that they have a better starting point. My Professor wants me to mesh the Geometry with Hexaeders. The Problem is now that the Geometry is very complex and there are still some tetraeders in the mesh, especially around the building, which is bad because that are the important zones. I have really no clue how to mesh the Geometry, so that the quality is good enough. Here is a photo of the actual meshing and the problem zones. http://imageshack.us/photo/my-images/96/bild6r.gif/ the big cuboid is of course the enveloping body. I did that with the boolean operation and sliced the Result in the middle, so that you can see the problem zones. I meshed that with Hexadominant, because there were no sweepable bodies available. Anyone an idea, how to solve that problem? Thank you very much

 October 23, 2012, 21:57 #2 Super Moderator     Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 27 if you want to mesh it with hexa, you can get better control by using icem cfd. It's difficult to get hexa in ansys meshing if you don't have sweepable bodies.... __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

October 24, 2012, 04:02
#3
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Quote:
 I meshed that with Hexadominant, because there were no sweepable bodies available. Anyone an idea, how to solve that problem?
Start slicing your geometry in DM until each volume become sweepable. In addition you should have all these volumes into one part, so you will have conformal mesh.

October 24, 2012, 08:31
#4
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Pete Drum
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Quote:
 Originally Posted by diamondx if you want to mesh it with hexa, you can get better control by using icem cfd. It's difficult to get hexa in ansys meshing if you don't have sweepable bodies....
Hey ,
thanks for your answers. Yes I already heard that meshing with hexa in ansys meshing isn't working very good, but we dont have the possibility to use icem cfd.

@sixkillers
could you explain how to do that, in a more detailed way? I dont know how to slice the Building exactly - here is another picture of the geometry:

http://imageshack.us/photo/my-images/196/geometryc.jpg/

Edit: Referring to the first picture that i posted, how can I generate an Inflation Layer between the Building (Hexa) and the "Air" (Tetra)around the building??

Last edited by fluent_beiyo; October 24, 2012 at 10:41.

 November 6, 2012, 09:28 #6 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,552 Blog Entries: 6 Rep Power: 53 did you make the mesh?

 November 8, 2012, 09:36 #7 Member   Tamil Nadu Join Date: Oct 2012 Posts: 44 Rep Power: 12 Hi... Mine is also a similar problem in meshing with GAMBIT. I want to model a building in GAMBIT 3D. Finally, aim of my project is to simulate the temperatures of the walls of building when water flows through pipes inserted in the ceiling (using Ansys Fluent). Is it possible to solve??

November 11, 2012, 09:33
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Sijal
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Hey

Are you still working on it. Any progress!

I am working on it. Wanted to ask can you simplify some details (Fig. 4)?

You want to mesh it inside or outside this domain?
Attached Images
 building1.jpg (44.5 KB, 119 views) building2.jpg (64.0 KB, 108 views) building3.jpg (58.8 KB, 89 views) building4.jpg (45.8 KB, 67 views)

 April 26, 2014, 05:55 FATAL error in meshing #9 New Member   mechatronicstudent Join Date: Apr 2014 Posts: 2 Rep Power: 0 hello everybody! I'm new in ANSYS. I have some problems in modeling & meshing. I'm trying with : ANSYS15-x64 and in Mechanical APDL. my system is : Intel core(i5) 2.27 with 4G RAM. O.S : Windows 8-x64. I create this rectangle : wp x = 0 wp y = 0 width = 2 height = 1 I meshed it in default mode. with PLANE55 element. Then I could Extrude it in " Cylindrical " Active C.S & with SOLID278 with " Extrude Area by XYZ" tool. It meshed & Extruded exactly. MY PROBLEM IS : But when I'm trying to Extrude it in " Cylindrical-Y " Active C.S it happens this error : *** FATAL *** CP = 4.094 TIME= 12:30:54 An allocation was made with a negative length requested: -8 Filename:..\src\FEM_advFront.cpp Linenum:3032. I'll be so grateful if any one can help me.