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May 10, 2012, 12:32 |
Courant Number
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#1 |
Member
Join Date: Apr 2012
Posts: 32
Rep Power: 13 |
I modified cavity sample a little by narrowing its moving lid.
The mesh was created successfully. But blockMesh exited with floating point exception for a few runs. the Courant Number has increased far > 1, and the U field has become saturated in the box. Any suggestion? I also changed the dimension to 3D by moving the faces in frontAndBack to fixedWalls. It seemed to me nothing evolved after the initial set-up. Last edited by sukye; May 10, 2012 at 12:53. |
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May 11, 2012, 08:02 |
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#2 | ||
Senior Member
Join Date: Aug 2010
Location: Groningen, The Netherlands
Posts: 216
Rep Power: 18 |
Hey there,
the information you provide is very little. Therefore it would help if you could post at least: - blockMeshDict - log of the creation of blockMesh / error message (?) - results of checkMesh and since you mentioned your courant number explodes: - log of the calculation process (error message) - controlDict Assuming that all solver/BC settings are set right this should bring us to the solution. Few comments on what you've got so far: Quote:
but you used it and then the calculation crashed? Quote:
mesh, it might be that you also have to add some more cells in the direction where you've got so far just 1 cell layer. Finally you mentioned that Co and U explode: since deltT (if you use the standart settings of the controlDict) and deltX are fixed and U explodes this might be more an BC issue than a meshing issue. I hope I could contribute regards |
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May 11, 2012, 09:52 |
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#3 |
Member
Join Date: Apr 2012
Posts: 32
Rep Power: 13 |
Thank you Colin for your reply.
I think theCourant number overflow problem is related to mesh size. The mesh at one corner of triangle is very small generated by blockMesh with default settings. How can I create triangle mesh? I searched in the forum to find someone mentioned it without solution. I will add more cells in the box to try to work 3D. But it is unclear to me why one box is sufficient for 2D while not for 3D. |
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May 14, 2012, 05:21 |
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#4 | |||
Senior Member
Join Date: Aug 2010
Location: Groningen, The Netherlands
Posts: 216
Rep Power: 18 |
Hi again
Quote:
Quote:
point. Quote:
wedge in stead of hex in blockMesh If you mean tetrahedra cells, there are no native OF meshers which could do that, but Salome and enGrid can create them. Again: a little bit more detailed description of your problem could help us to help you more easy. Including some pictures/sketches could clarify a matter pretty fast as well as some output form some log files. For more questions on that see the sticky post in the main OF Forum! regards Colin |
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May 16, 2012, 11:24 |
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#5 |
Member
Join Date: Apr 2012
Posts: 32
Rep Power: 13 |
Thank you Colin,
It turns out I use gmsh to generate mesh. From your post, I will guess that we need wedge shaped blocks to make triangle mesh possible. Right? I also mention in another post http://www.cfd-online.com/Forums/ope...ientation.html that my mesh by gmsh cant pass checkMesh. |
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