# Y+ quick question...probably pretty easy.

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 May 9, 2012, 18:30 Y+ quick question...probably pretty easy. #1 Member   Join Date: Jun 2011 Posts: 48 Rep Power: 11 Hey all, Just wondering, when I look at a 3d FLUENT simulation results, and I look at contours on a wall surface of Wall Y+...what is that based off of? My understanding is that the "y" value in the y+ equation is based off of the distance from the wall...so when you look at contours of Y+ on the wall itself, are these based off of the 1st node off the surface? If so, is there a source that says this? I can't find it in the fluent user guide. Thanks in advance for any replies!

 May 11, 2012, 06:01 #2 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,539 Blog Entries: 6 Rep Power: 50 you are correct partially. There are others parameters are there to calculate the Y+.

May 14, 2012, 02:19
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Quote:
 Originally Posted by eishinsnsayshin Hey all, Just wondering, when I look at a 3d FLUENT simulation results, and I look at contours on a wall surface of Wall Y+...what is that based off of? My understanding is that the "y" value in the y+ equation is based off of the distance from the wall...so when you look at contours of Y+ on the wall itself, are these based off of the 1st node off the surface? If so, is there a source that says this? I can't find it in the fluent user guide. Thanks in advance for any replies!
you are exactly correct about y and y+. When you plot "Wall Y+", you are plotting the y+ of the 1st closest grid point to the wall. Also note that when calculating y+, the distance to the NEAREST wall is used for the y. The distance to the nearest wall is calculated using the distance formula.

 May 14, 2012, 21:13 #4 Member   Join Date: Jun 2011 Posts: 48 Rep Power: 11 Thanks for the answers!!