# How is yplus calculated in OF?

 Register Blogs Members List Search Today's Posts Mark Forums Read

 March 18, 2010, 16:22 How is yplus calculated in OF? #1 New Member   Join Date: Mar 2010 Posts: 2 Rep Power: 0 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.

 March 22, 2010, 09:24 #2 New Member   Join Date: Mar 2010 Posts: 2 Rep Power: 0 Bump. Any input?

 March 27, 2010, 23:07 #3 Senior Member   Sandy Lee Join Date: Mar 2009 Posts: 213 Rep Power: 11 Yes, good method to output from parafoam.

May 19, 2010, 11:20
#4
Senior Member

Louis Gagnon
Join Date: Mar 2009
Location: Milano, Italy
Posts: 244
Rep Power: 11
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.

 May 19, 2010, 19:37 #5 Senior Member   Sandy Lee Join Date: Mar 2009 Posts: 213 Rep Power: 11 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.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Thomas Baumann OpenFOAM Running, Solving & CFD 26 December 21, 2013 23:16 sanchezz CFX 17 January 11, 2010 05:45 Chebeba CFX 4 March 23, 2006 05:18 Luo FLUENT 24 April 11, 2000 06:07 Andrew Main CFD Forum 4 April 8, 1999 04:43

All times are GMT -4. The time now is 10:35.