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Y+ range for different turbulence models and wall functions |
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April 26, 2022, 03:40 |
Y+ range for different turbulence models and wall functions
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#1 |
New Member
amin
Join Date: Jun 2021
Posts: 12
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Hello everyone
I read somewhere that the Y+ range for different turbulence models is as follows: Spalart Almaras : Y+~1 k-ω : Y+<1 K-ε/standard wall function : 30<Y+<300 K-ε/scalable wall function : Y+>11 K-ε/Non equilibrium wall function : 30<Y+<300 K-ε/Enhance wall treatment : Y+<5 * Is the above correct? * Can anyone suggest a valid reference for Y+ ranges? Unfortunately, there is no exact reference for Y + and in different books and websites, there are different explanations that are confusing. Thanks in advance |
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April 28, 2022, 06:56 |
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#2 | |
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Void_CFD-user
Join Date: Feb 2022
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Quote:
In Fluent, K-w,Spalart Almaras and Menter Lechner treatement are y+ insensitive. That dosen't mean using a good y+ won't give you a better solution. There's no strict definition for y+ range these days, depends on how accurate you wanna be. Also as far as I know, scalable wall function helps avoid getting bad results from standard wall funstion in case of grid refinement. Not sure if there's a recommended y+ for scalable. Feel free to correct me if I'm wrong. |
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April 30, 2022, 03:06 |
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#3 | |
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amin
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May 5, 2022, 11:20 |
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#4 |
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Luca
Join Date: Mar 2021
Location: Italy
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Generally, when you are using models able to solve directly for the variables at the wall, y+ should be <= 1 or at least <5 (as far as I know, this is the y+ limit related to the viscous sublayer within the BL region). Instead, when you are adopting wall funtions, generally you need to maintain y+ within the logarithmic range, so 30 < y+ < 300 (I know it is true at least for standard and non-equilibrium).
I do not know if specific intervals exist for enhance or scalable wall functions; for more info, you can also try to have a look at the original scientific papers |
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