# y+ yplus

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

 November 19, 2007, 05:53 y+ yplus #1 Seve Guest   Posts: n/a HI! I simulate a microgap flow (height 100um). With k epsilon turbulence model. First my mesh's height consists of 10 layers totaly. my values for y+ have been 7

 November 19, 2007, 08:55 Re: y+ yplus #2 Jia Guest   Posts: n/a If you wanna to use k epsilon model, the y+ must be much bigger than 10, because k epsilon model use wall function at near wall region. You can find more instructions in the CFX help. After all, what's your problem?

 November 20, 2007, 04:49 Re: y+ yplus #3 frank Guest   Posts: n/a i think, for such a narrow gap, is there any necessity to use turbulence flow model?

 November 20, 2007, 05:41 Re: y+ yplus #4 Jon P Guest   Posts: n/a Is using a different turbulence model not possible that desires lower Y+?

 November 20, 2007, 07:47 Re: y+ yplus #5 Dr. Flow Squad Guest   Posts: n/a Microgap flow must be laminar!

 November 25, 2007, 13:12 Re: y+ yplus #6 Omer Guest   Posts: n/a SST can resolve boundary layers if Y+ less than 2. So you need to make the mesh finer. But then if microgap flow is laminar, things would be different , wouldn't they?

 November 26, 2007, 02:25 Re: y+ yplus #7 Dr. Flow Squad Guest   Posts: n/a y+ is a turbulent parameter. It doesn't exist in laminar flow.

 November 26, 2007, 08:31 Re: y+ yplus (with a slight off-topic question) #8 jakjak Guest   Posts: n/a I am not sure if this question has been asked, but I have always wonder... If you have enabled any one of the turbulence (say, just the RANS) models, but most of your flow parameters are in laminar condition. How does the solver actually treat it? Would that give un-physical results? From Omer's question, it led me to think of the laminar sublayer that exists near the wall under turbulence flow condition. So, when y+ < 2, the flow in that region is laminar, does that same turbulent model is being applied there? thanks in advance for answering. jak

 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 mohammad Main CFD Forum 3 January 12, 2011 00:23 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 22:04.