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can OpenFoam model a pole in Cylindrical mesh??

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Old   October 26, 2014, 21:03
Default can OpenFoam model a pole in Cylindrical mesh??
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I am making a 3D cylindrical mesh for LES computations of premixed flames.

I would like to know if OpenFoam can correctly model singularities or poles at the origin (as shown in the attached figure) correctly, or would I have to mesh my geometry in a different manner.

Would really appreciate any help on this topic. Thanks!
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Old   October 27, 2014, 17:17
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I had previously tested this with rhoPimpleFoam, and did notice abnormal action along the cylinder axis (center of the "pie slices") where the cell skewness gets really large. I then tried rounding out one square hex, but this introduced abnormalities where the corners were stretched out (probably for the same reason). I then meshed a square in the center of the circle which simulated properly.

I honestly didn't spend too much effort trying to see if there were more advanced solver options to account for skewedness, I just changed the mesh. Somebody else with more experience may speak to your exact question.

Good luck!
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Old   October 28, 2014, 05:05
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I am wondering: why..? I mean, people use o-grids for this normally. I didn't really question this up to now, because I thought this is pretty common. Can you explain, why you prefer this way of meshing?
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Old   October 28, 2014, 13:11
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You are absolutely right, people use o-grids. It may have been my specific mesh/configuration/BC, but there were false temp/density iso's which protruded down the cylinder axis which should not have been the case. I was merely warning the OP that it is possible if he's not careful. As I said, I didn't play with it too much because it was simple enough for me to change the grid.

To keep an o-grid in my system I had calculated an excessively dense mesh in the center to keep the skewness down (increasing #/meter of "onion shells" around the axis where the "pie slice" tips narrow to zero @ the center). I have very little experience in CFD, but in my simulation, the denser mesh & running >3 nonOrthogonalCorrectors will slow me down, and I guessed a nice cubic in the center may help the solver converge more rapidly...? I wanted to spend the mesh density near the walls where there's something more interesting going on. Am I way off?
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Old   October 28, 2014, 14:14
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Even I am modeling my mesh using an O-grid but was wondering if OpenFoam could model poles because for an axisymmetric grid it is able to take into account pole formation.

Anyways thanks for your reply Chris!
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Old   May 30, 2017, 22:03
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Although it might be late for you, but I do have what you want.

You can change the length and radius from the .m4 file.
Using the following command, you can get the blockMeshDict from the .m4 file.
Code:
m4 circle.m4 > blockMeshDict
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File Type: jpg cylinder.jpg (191.6 KB, 16 views)
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File Type: txt blockMeshDict.txt (4.0 KB, 9 views)
File Type: txt circle.m4.txt (5.3 KB, 12 views)
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