Y+ in TurboGird # from CFX ???

FAKHREDDINE · July 25, 2016, 07:38

Hello Guys please I have A problem
In turboGrid I created a fine mesh and I used this option:

Boundary Layer Refinement Control
Method : First Element Offset
The actual Y+ in turboGrid was set to a value of 1 since I am using SST model for high Reynolds NUMBER and I need to see the velocity profile development in the viscous sub layer

But the results in CFX Post showed different results, the actual Y+ in CFX Post is between 57 and 5000 ????
Please I dont understand whats going on

I will highly appreciate if you help me with

ghorrocks · July 25, 2016, 08:19

Please do not post multiple identical posts. I have removed the duplicate posts.

-Maxim- · July 27, 2016, 01:54

I assume TurboGrid is calculating the expected y+ from the Reynolds Number you put in.
CFD Post is using the actual flow velocity to calculate the y+ values at the respective surfaces.
That's at least how it makes sense in my head

FAKHREDDINE · July 27, 2016, 05:52

-Maxim- Thank you very much for your answer

Actually, the question is whether the specified Reynolds number in TurboGrid is representing the Machine Reynolds number (Turbine rotor) or the Reynolds Number in the viscous sub layer ( which is relatively too low ) ?

Thanks again fro your help

July 25, 2016, 07:38	Y+ in TurboGird # from CFX ???	#1
FAKHREDDINE Member Yuva Join Date: Oct 2015 Location: Korea Rep of Posts: 33 Rep Power: 10	Hello Guys please I have A problem In turboGrid I created a fine mesh and I used this option: Boundary Layer Refinement Control Method : First Element Offset The actual Y+ in turboGrid was set to a value of 1 since I am using SST model for high Reynolds NUMBER and I need to see the velocity profile development in the viscous sub layer But the results in CFX Post showed different results, the actual Y+ in CFX Post is between 57 and 5000 ???? Please I dont understand whats going on I will highly appreciate if you help me with

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July 25, 2016, 08:19		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	Please do not post multiple identical posts. I have removed the duplicate posts.

July 27, 2016, 01:54		#3
-Maxim- Senior Member Maxim Join Date: Aug 2015 Location: Germany Posts: 415 Rep Power: 13	I assume TurboGrid is calculating the expected y+ from the Reynolds Number you put in. CFD Post is using the actual flow velocity to calculate the y+ values at the respective surfaces. That's at least how it makes sense in my head

July 27, 2016, 05:52		#4
FAKHREDDINE Member Yuva Join Date: Oct 2015 Location: Korea Rep of Posts: 33 Rep Power: 10	-Maxim- Thank you very much for your answer Actually, the question is whether the specified Reynolds number in TurboGrid is representing the Machine Reynolds number (Turbine rotor) or the Reynolds Number in the viscous sub layer ( which is relatively too low ) ? Thanks again fro your help