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-   -   yPlus in OpenFOAM (https://www.cfd-online.com/Forums/openfoam-solving/253805-yplus-openfoam.html)

anubasu December 31, 2023 08:36

yPlus in OpenFOAM
 
Hi guys,

I am using k-epsilon turbulence model in interFOAM. Currently my yPlus values range from min:2 to max: 400 with an average of 10 and changes with time. Will the yPlus value become constant as the simulation reaches steady state? I am simulating flow in a pipe. So what should be my ideal yPlus value? is it around 30 for k-e model?
Thanks.

NotOverUnderated December 31, 2023 16:38

Assuming you're using the standard kEpsilon:

- You must use wall functions.
- Your yPlus must be greater than 30 and less than say 200 (this is not hard limit). Usually, your yPlus should be around 50 or 60.

anubasu January 4, 2024 11:07

Quote:

Originally Posted by NotOverUnderated (Post 862464)
Assuming you're using the standard kEpsilon:

- You must use wall functions.
- Your yPlus must be greater than 30 and less than say 200 (this is not hard limit). Usually, your yPlus should be around 50 or 60.

Hi , I am using the default ke model in Openfoam and the BCs defaultly available in 0 dir in OpenFOAM. Is this fine?

saeed jamshidi January 6, 2024 12:33

2 Attachment(s)
Hi anubasu,
Let me add somthing to this thread.

For the cases you are going to use k-epsilon turbulence model you should use wall functions in which y-pluse belongs to the logarithmic region, because k-epsilon turbulence model isn't accurate just near the wall due to some assumtions in order to evaluate this model constant numbers;
Attachment 97976 & Attachment 97975

Besides, each tutorial has introduced delibrately in order to convey a message and purpuse. For example, I have seen motorbike case in both simpleFoam and pisoFoam. You can develope and use tutorials based on your requirement.
However, the contents of the tutorials are correct.


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