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February 21, 2011, 05:54 |
smallestDist / y distance problem
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#1 |
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 |
Hej,
I have noticed that the smallestDist function in the class cellDistFuncs http://foam.sourceforge.net/docs/cpp...lDistFuncs.php seems to calculate the smallest difference in a way that it gives the wrong distance. I attached a picture in order to show what I mean. The distance towards the center of the channel seems to be right, but when the distances of the cells closer to the wall are supposed to be calculated, they are not the what one expects. In the attached pictures, the only walls are the boundaries on top and bottom. And it reports the cells closest to the wall to have a distance of 1.08 mm. The whole channel on the other hand, as one can see, is only 5.4mm wide. Does anybody know why this behavior is like this? It doesn't make sense to me.
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~roman |
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March 17, 2011, 07:32 |
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#2 |
Member
José
Join Date: Jan 2011
Posts: 73
Rep Power: 15 |
Hi Roman,
I am struggling a lot with this issue too. Have you got any insight for that? I am doing cfd around an airfoil and I need the correct value of this distance in order to calculate yPlus. Keep me updated if you get sth! I will do so too! Regards, José |
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March 17, 2011, 07:43 |
y plus calculations
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#3 |
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 |
Hej,
in case you want to calculate y plus for compressible flow and turbulence models with wall functions you should be able to do this with Code:
yPlusRAS Code:
yPlusLES
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~roman |
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March 17, 2011, 07:51 |
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#4 |
Member
José
Join Date: Jan 2011
Posts: 73
Rep Power: 15 |
Hi!
Thank you for your advice. I already know that. I am using RANS, so I started using yPlusRAS but it gives y* instead of y+ (see this thread if you want to read about this...). Thus, I am using one code from one guy which is an adaptation of yPlusLES to RANS. here you can find it. To calculate y + as you can see in the thread I have sent to you you need the 1st cell height, i.e. I would need the tool you were referring to in the message running well. Anyway...if you know how to fix this calculation of the nearWall tool, let me know! Regards, José |
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March 17, 2011, 08:01 |
nearWall
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#5 |
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 |
I think one way to do this could be by taking the distance normal from the cellCenter (cell at the wall) to the faceCenter (wallpatch). Since the velocity is stored at the cell center, this should then give the velocity at the cell center of the first cell and your y distance from the wall.
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~roman |
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March 17, 2011, 08:07 |
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#6 |
Member
José
Join Date: Jan 2011
Posts: 73
Rep Power: 15 |
Thanks Roman. I know this, but I am not very into programming OpenFOAM, this is why I was looking for a code with this already implemented.
Thank you anyway, Regards, José |
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March 17, 2011, 08:08 |
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#7 |
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 |
maybe I will try this out soon, but unfortunately I don't have too much time at the moment. Hopefully, over the coming weeks I will be able to do some more programming.
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