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-   -   How is yplus calculated in OF? (http://www.cfd-online.com/Forums/openfoam-solving/73877-how-yplus-calculated.html)

 jdd82 March 18, 2010 16:22

How is yplus calculated in OF?

Can someone offer some insight into what OF does when you calculate "yPlusRAS"? When I view the output "y" (distance from the wall) in Paraview, the numbers look right. When I plot "yplus", it seems to only give me one non-zero value at the node closest to the wall. Also, I can't seem to figure out how it exactly arrives at that number - does it use u_tau = sqrt(k)*C_mu^0.25 (where k is the turbulent kinetic energy)? If so, which value of k does it use? The value at the node nearest to the wall?

I apologize if this was posted elsewhere but I couldn't find any specific info on it and it was a bit unclear looking in the source code.

 jdd82 March 22, 2010 09:24

Bump. Any input?

 sandy March 27, 2010 23:07

Yes, good method to output from parafoam. ;)

 louisgag May 19, 2010 11:20

Quote:
 When I plot "yplus", it seems to only give me one non-zero value at the node closest to the wal
Similar situation here, yPlusRas outputs values for yPlus on my wall that seem to make sense but when I plot with paraview the values are different.

For example yPlusRas outputs
Code:

`y+ : min: 0.300666258352 max: 4.7795851505 average: 2.08585637331`
and paraview shows me values of yPlus that go from 0.002 to 78, which doesn't make sense considering my mesh resolution and velocity at wall are fairly constant...

EDIT: the error seems to come from the yPlus file that is being written.

 sandy May 19, 2010 19:37

How to give the yplus to multiphase flows, it seems that values in multiphase pattern and single phase pattern are different to the wall turbulence. Who can give some light? Thanks.

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