How can I increase Y+ ?!

Vietazz · September 11, 2013, 11:53

Hello everyone!

I have a question that it could seem so obvious! actually, I work on a cfd model, and I have read some theorique documentations about the law of the wall. I know that viscosity, distance of the first cell from the wall and friction velocity are basically the mean parametres that could influence the variation of Y+.
My question is how can I manage my mesh to have a desired value of Y+, in my actual case is 50 !? I tried to refine my mesh close to the wall at the first time, after I make it corser , I obtain Y+=20 at best, in both of the cases.
here is my configuration: Uref =45 m/s and ν=1.5e-5 [SI].

Thanks in advance for any help

!

ghost82 · September 11, 2013, 12:37

Hi!
to have higher yplus value your nodes near the walls have to be located farther away than where they are now.
You can calculate the distance of the nodes from the wall with this tool (check result in estimated wall distance):
http://www.cfd-online.com/Tools/yplus.php

Daniele

Vietazz · September 12, 2013, 04:26

Hi Daniele.

thanks for your reply! that will help me!

September 11, 2013, 11:53	How can I increase Y+ ?!	#1
Vietazz New Member Join Date: Aug 2013 Location: Vietnam Posts: 11 Rep Power: 12	Hello everyone! I have a question that it could seem so obvious! actually, I work on a cfd model, and I have read some theorique documentations about the law of the wall. I know that viscosity, distance of the first cell from the wall and friction velocity are basically the mean parametres that could influence the variation of Y+. My question is how can I manage my mesh to have a desired value of Y+, in my actual case is 50 !? I tried to refine my mesh close to the wall at the first time, after I make it corser , I obtain Y+=20 at best, in both of the cases. here is my configuration: Uref =45 m/s and ν=1.5e-5 [SI]. Thanks in advance for any help !

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September 11, 2013, 12:37		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	Hi! to have higher yplus value your nodes near the walls have to be located farther away than where they are now. You can calculate the distance of the nodes from the wall with this tool (check result in estimated wall distance): http://www.cfd-online.com/Tools/yplus.php Daniele

September 12, 2013, 04:26		#3
Vietazz New Member Join Date: Aug 2013 Location: Vietnam Posts: 11 Rep Power: 12	Hi Daniele. thanks for your reply! that will help me!