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K-omega SST Wall functions

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Old   March 20, 2019, 04:57
Default K-omega SST Wall functions
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I have noticed when selecting K-omega SST as a turbulence model that there is no option to select wall functions whereas when selecting K-epsilon there is? Is this because there is no wall functions used in K-omega SST or just because Ansys doesn't allow the use of them for this model? Additionally, what should the Y+ range be for K-omega SST, is there are no wall functions then it should be 1-5, is that correct?

Thanks in advance
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Old   March 20, 2019, 08:23
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There's only one wall function for the omega equation so there are no options. You get what you get. This wall function is rather crappy though because...

k-w (SST or not) is meant to be integrated all the way to the wall and yes you should be using it for low y+. If you are using a super high y+ grid, then go with regular k-epsilon.
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Old   March 25, 2019, 09:36
Default eddy viscosity
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i used the SST K Omega model to solve my simulation i obtained eddy viscosity but i need the molecular viscosity. how i can do this conversion from eddy viscosity to molecular viscosity
thanks
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Old   March 25, 2019, 09:54
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Quote:
Originally Posted by josy View Post
i used the SST K Omega model to solve my simulation i obtained eddy viscosity but i need the molecular viscosity. how i can do this conversion from eddy viscosity to molecular viscosity
thanks

Don't hijack other people's threads for a different discussion!


There is no conversion. They are unrelated. Eddy viscosity is a flow property related to turbulence. Molecular viscosity is a material property which is readily available. If you got the eddy viscosity you can also find the molecular viscosity.
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Old   March 25, 2019, 10:46
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Thank you LuckyTran For your answers.
But how i can reach the molecular viscosity?
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Old   March 25, 2019, 12:04
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How did you get to eddy viscosity?


If you're in the GUI and trying to make a contour or monitor or anything, molecular viscosity is grouped in properties.
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Old   March 25, 2019, 13:00
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To have the eddy viscosity i run the simulation and go in the part result of ansys fluent and choice calculation --> areaAve --> Eddy viscosity --> Apply.
I didn't habe the molecular viscosity a Variable(result)to choice
So i though that i can take the Eddy viscosity and convert it.
Did you have any possibility ? PLEASE
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Old   March 26, 2019, 07:54
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I don't know what to tell you except it's right there. It's not magic.



Maybe you can explain what you are (not) doing.
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Old   March 26, 2019, 08:51
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after initialisation i have this error

"Error: domain-var-value: undefined variable
Error Object: pb/sg-pb-dqmom?"

what is it mean please
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Old   March 26, 2019, 09:39
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Make your own thread! This is no longer a discussion of k-w SST nor wall functions. I am not answering any more of your queries in this thread unless it's related to one of those two topics. You keep coming up with new problems.
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