About the nut wall function in RAS

spwater · November 15, 2009, 06:11

Hello everyone,
This is Pei, I have a question about the wall function of nu in RAS model, I found in the code,

nutw[faceI] = nuw[faceI]*(yPlus*kappa_/log(E_*yPlus) - 1.0)

However, the book I am reading says it should be

nutw[faceI] = nuw[faceI]*(yPlus*kappa_/log(E_*yPlus) )

Can angone explain the difference? Thank you very much!

Anne Lincke · October 28, 2011, 10:37

Hey Pei,

In the log-Layer we can assume that nu_t >>nu
Therefore we can approximate

nuw[faceI]*(yPlus*kappa_/log(E_*yPlus) - 1.0) = nuw[faceI]*yPlus*kappa_/log(E_*yPlus)-nuw[faceI]
~~nuw[faceI]*yPlus*kappa_/log(E_*yPlus)

November 15, 2009, 06:11	About the nut wall function in RAS	#1
spwater New Member Shui Pei Join Date: Mar 2009 Posts: 19 Rep Power: 6	Hello everyone, This is Pei, I have a question about the wall function of nu in RAS model, I found in the code, nutw[faceI] = nuw[faceI](yPluskappa_/log(E_yPlus) - 1.0) However, the book I am reading says it should be nutw[faceI] = nuw[faceI](yPluskappa_/log(E_yPlus) ) Can angone explain the difference? Thank you very much!

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Need some wall function approaches!	yka8150	Main CFD Forum	0	September 21, 2009 23:08
LES automatic wall function	Sungho Yoon	CFX	7	October 9, 2008 07:00
Moving wall with sin function	Malik	FLUENT	1	January 17, 2008 07:14
Droplet Evaporation	Christian	Main CFD Forum	2	February 27, 2007 06:27
Wall function	tod	Phoenics	1	May 19, 2003 05:05

October 28, 2011, 10:37		#2
Anne Lincke Senior Member Anne Lincke Join Date: Aug 2010 Location: Hamburg Posts: 131 Rep Power: 4	Hey Pei, In the log-Layer we can assume that nu_t >>nu Therefore we can approximate nuw[faceI](yPluskappa_/log(E_yPlus) - 1.0) = nuw[faceI]yPluskappa_/log(E_yPlus)-nuw[faceI] ~~nuw[faceI]yPluskappa_/log(E_*yPlus)