# 2D axissym mesh problem

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 August 7, 2006, 18:02 I want to create a 2D axis-sym #1 Member   chris book Join Date: Mar 2009 Posts: 85 Rep Power: 9 I want to create a 2D axis-sym mesh: I have used the following blockMeshDict vertices ( (0 0 0) (44.956 -1.963 0) (44.956 1.963 0) (0 0 90) (44.956 -1.963 90) (44.956 1.963 90) ); blocks ( hex (0 1 2 0 3 4 5 3) (20 1 20) simpleGrading (1 1 1) ); edges ( arc 1 2 (45 0 0) arc 4 5 (45 0 90) ); patches ... But when I run checkMesh, the util complains about highly skewed cells! --> FOAM Warning : From function primitiveMesh::checkFaceSkewness(const bool report, labelHashSet* setPtr) const in file meshes/primitiveMesh/primitiveMeshCheck.C at line 834 Large face skewness detected. Max skewness = 284.634 percent. This may impair the quality of the result. 40 highly skew faces detected. Writing 40 skew faces to set skewFaces What is wrong with my mesh. Is there something what I can do to get rid of the bad skewness???

 September 15, 2006, 08:40 Can nobody comment my mesh pro #2 Member   chris book Join Date: Mar 2009 Posts: 85 Rep Power: 9 Can nobody comment my mesh problem?

 September 15, 2006, 12:01 checkMesh says that there is s #3 Super Moderator   Mattijs Janssens Join Date: Mar 2009 Posts: 1,416 Rep Power: 17 checkMesh says that there is skewness for boundary faces. If you check you'll see that all your wedge faces are skew, i.e. the face centre is not the normal projection of the cell centre. Make the skew angle larger and you'll see where the error comes from.

 September 15, 2006, 12:16 Thanks Mattijs, so the prob #4 Member   chris book Join Date: Mar 2009 Posts: 85 Rep Power: 9 Thanks Mattijs, so the problem with highly skewed cells is unavoidable with a "wedge" geomertry right? Please correct me if I am wrong. If not, how to do a better wedge mesh?

 September 17, 2006, 13:06 Ok the faces which checkMesh c #5 Member   chris book Join Date: Mar 2009 Posts: 85 Rep Power: 9 Ok the faces which checkMesh complains belong to cells which are aligned along the axis of my wedge. So I was wondering if someone is able to tell me how to create a wedge without skewed faces? See my first message this is the way I am creating the wedge at the moment.

 September 17, 2006, 13:32 I suspect what bothers you are #6 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,784 Rep Power: 22 I suspect what bothers you are the faces on the front and back surface of the wedge - you can safely ignore the message there. If you wish, you can remove zero-area faces on the axis itself, simply be creating only one set of axis points and using duplicates in block definition. Enjoy, Hrv __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

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