Axissymmetric pipe Simulation with unequal zero wall velocity

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July 14, 2009, 06:41
Axissymmetric pipe Simulation with unequal zero wall velocity
#1
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Join Date: Apr 2009
Location: Karlsruhe, Germany
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Hallo all,

I built an axissymmetric mesh with the blockmesh utility. It is a pipe with an inlet and outlet, on top a wall, down is the axis and left and right are wedges.

Running with icofoam works, but looking at the velocity at the wall there are nonzero values.

I plotted the velocity-values in paraview.
I also used the sampledict with different interpolation schemes (cell, cellPoint, cellPointFace).
Plotting the wall surface shows again zero values.

Has anybody an idea?

Thanks, Thomas
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Attached Files
 pipe.tar.gz (1.9 KB, 10 views)

July 14, 2009, 07:02
#2
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Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
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Quote:
 Originally Posted by Thomas Baumann I plotted the velocity-values in paraview.
Looks like ParaView didn't plot the value directly at the wall.
Can you show us the result with with sample?
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July 14, 2009, 08:28
#3
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Join Date: Apr 2009
Location: Karlsruhe, Germany
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Hallo,

here are the velocity-profils made by the sampledict with the three interpolation schemes: cell, cellPoint and cellPointFace.

The set was made by a uniform line with 40 values from r =0.9R until r = R.
Attached Files
 pos_cellPointFace_U.txt (2.6 KB, 5 views) pos_cellPoint_U.txt (2.6 KB, 1 views) pos_cell_U.txt (2.6 KB, 2 views)

 July 14, 2009, 08:51 #4 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 15 Instead of using a line with 40 points you can try using a midPointAndFace type, so you will get values at points corresponding to your discretization. In this case you can even omit the nPoints-entry! Something like this: Code: ```interpolationScheme cellPointFace; setFormat raw; surfaceFormat foamFile; sets ( line_horizontal { type midPointAndFace; axis z; start (0.8838 0.8838 0); end (0.8838 0.8838 5); } );``` __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 July 14, 2009, 09:08 #5 Member   Join Date: Apr 2009 Location: Karlsruhe, Germany Posts: 96 Rep Power: 12 I have used midPointAndFace, too, but nothing changed. There is still nonzero velocity at the wall.

 July 14, 2009, 11:41 #6 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 15 I have played with the case but could not find a solution to this problem, at first glance. Anyone got further ideas? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 July 15, 2009, 05:36 #7 Member   Join Date: Apr 2009 Location: Karlsruhe, Germany Posts: 96 Rep Power: 12 I think the interpolation sheme is the problem. I changed in the sampledict the interpolationScheme to cell (constant over cells) and the type to midPoint (one Point per cell) and the results are much better. Plotting the velocity graphs with gnuplot show good results. Last edited by Thomas Baumann; July 15, 2009 at 12:06.

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