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[mesh manipulation] TranformPoints gives skewed mesh Possible Bug |
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March 19, 2008, 22:48 |
TranformPoints gives skewed mesh Possible Bug
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#1 |
Member
Andrew King
Join Date: Mar 2009
Location: Perth, Western Australia, Australia
Posts: 82
Rep Power: 17 |
Description:
I am trying to build a mesh by flipping and combining a submesh. To construct the mesh I would like to flip the original mesh and merge the original and the flipped mesh together. ie. if the original mesh is called "left" then the process is roughly cp -rv left right transformPoints . right -scale "(-1 1 1)" (or alternatively transformPoints . right -rotate "((1 1 1) (-1 1 1))" - it doesn't matter which one as both fail" mergeMesh . left . right the transformPoints step always results in a bad mesh (according to checkmesh). Solver/Application: transformPoints or checkMesh Source file:King Testcase: Platform: linux32 (but most likely non-specific) Version: OpenFOAM-1.4.1 (extend) Notes: I have attached a test case that illustrates the problem. taking the case and running blockMesh and checkMesh gives: Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Topological cell zip-up check OK. Face vertices OK. Face-face connectivity OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface defaultFaces 600 602 ok (closed singly connected surface) Checking geometry... Boundary openness (3.41901e-17 3.41901e-17 -1.37863e-18) OK. This mesh has no valid solving directions. dirs = (-1 -1 -1). Please check mesh definition for empty patches. This is a 0-D mesh Domain bounding box: (0 0 0) (0.001 0.001 0.001) Max cell openness = 1.65436e-16 OK. Max aspect ratio = 1 OK. Minumum face area = 1e-08. Maximum face area = 1e-08. Face area magnitudes OK. Min volume = 1e-12. Max volume = 1e-12. Total volume = 1e-09. Cell volumes OK. Mesh non-orthogonality Max: 8.53774e-07 average: 0 Non-orthogonality check OK. Face pyramids OK. Max skewness = 6.50521e-15 OK. Min/max edge length = 0.0001 0.0001 OK. All angles in faces OK. Face flatness (1 = flat, 0 = butterfly) : average = 1 min = 1 All face flatness OK. Failed 1 mesh checks. End then after running transformPoints . block -scale "(-1 1 1)" checkMesh gives Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Topological cell zip-up check OK. Face vertices OK. Face-face connectivity OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface defaultFaces 600 602 ok (closed singly connected surface) Checking geometry... Boundary openness (3.41901e-17 -3.41901e-17 1.37863e-18) OK. This mesh has no valid solving directions. dirs = (-1 -1 -1). Please check mesh definition for empty patches. This is a 0-D mesh Domain bounding box: (-0.001 0 0) (0 0.001 0.001) ***High aspect ratio cells found, Max aspect ratio: 6.29961e+191, number of cells 1000 <<Writing 1000 cells with high aspect ratio to set highAspectRatioCells Minumum face area = 1e-08. Maximum face area = 1e-08. Face area magnitudes OK. Min volume = 2e-300. Max volume = 2e-300. Total volume = 2e-297. Cell volumes OK. Mesh non-orthogonality Max: 180 average: 180 <font color="ff0000"> ***Number of non-orthogonality errors: 2700. <<Writing 2700 non-orthogonal faces to set nonOrthoFaces ***Error in face pyramids: 6000 faces are incorrectly oriented. <<Writing 3300 faces with incorrect orientation to set wrongOrientedFaces Max skewness = 5.42101e-15 OK. Min/max edge length = 0.0001 0.0001 OK. All angles in faces OK. Face flatness (1 = flat, 0 = butterfly) : average = 1 min = 1 All face flatness OK. Failed 4 mesh checks. End</font> Am I missing a stage or option to do this conversion? or is this a bug in transformPoints (or checkMesh)? cheers, Andrew block.tgz
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Dr Andrew King Fluid Dynamics Research Group Curtin University |
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March 20, 2008, 07:00 |
The calculation of the transfo
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#2 |
Senior Member
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,419
Rep Power: 26 |
The calculation of the transformation tensor breaks down (no clearly defined path to rotate over 180 degrees). Use two steps:
// Rotate 90 degrees around z-axis transformPoints .. block -rotate '((1 0 0)(0 1 0))' // Rotate 90 degrees around z-axis transformPoints .. block -rotate '((1 0 0)(0 1 0))' |
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March 20, 2008, 09:32 |
why don't you just use mirrorM
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#3 |
Senior Member
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 21 |
why don't you just use mirrorMesh? it does everything including the merging for you.
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March 25, 2008, 21:33 |
Thanks, doing the transformati
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#4 |
Member
Andrew King
Join Date: Mar 2009
Location: Perth, Western Australia, Australia
Posts: 82
Rep Power: 17 |
Thanks, doing the transformation in two steps worked, I thought I may have missed something.
As for mirrorMesh I actually need to rotate the mesh 180 degrees, not mirror it (though I realize that's not clear in my post). cheers, Andrew
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Dr Andrew King Fluid Dynamics Research Group Curtin University |
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