Choosing the correct y+

ReCr · March 24, 2015, 16:04

Can someone point me in the right direction to choosing an appropriate value for y+. Really just looking for a good source.

fluid23 · March 24, 2015, 16:23

You are already there. Read over the turbulence modeling and wall equations on teh wiki for this site. Your asnwer lies within. However, it is really a product of the turbulence model you choose.

TimCFD · March 25, 2015, 14:43

It´s really hard to make a general statement about the "correct" y+ value. First of all it depends on the wall treatment formulations that are available for your turbulence model to calculate the boundary layer. I am talking about a so-called low-Reynolds formulation and wall functions. The other important aspect is the physics of your problem (flow separation, ...).

As a rule of thumb for industrial problems
low-Re -> y+ < 1
wall function -> 30 < y+ < 150

References can be found in all standard CFD books.

March 24, 2015, 16:04	Choosing the correct y+	#1
ReCr New Member Adam Join Date: Nov 2014 Posts: 6 Rep Power: 11	Can someone point me in the right direction to choosing an appropriate value for y+. Really just looking for a good source.

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March 24, 2015, 16:23		#2
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	You are already there. Read over the turbulence modeling and wall equations on teh wiki for this site. Your asnwer lies within. However, it is really a product of the turbulence model you choose.

March 25, 2015, 14:43		#3
TimCFD New Member Tim Meier Join Date: Mar 2015 Posts: 16 Rep Power: 11	It´s really hard to make a general statement about the "correct" y+ value. First of all it depends on the wall treatment formulations that are available for your turbulence model to calculate the boundary layer. I am talking about a so-called low-Reynolds formulation and wall functions. The other important aspect is the physics of your problem (flow separation, ...). As a rule of thumb for industrial problems low-Re -> y+ < 1 wall function -> 30 < y+ < 150 References can be found in all standard CFD books.