Omega wall treatment change via UDF

HHOS · February 14, 2024, 12:35

Hello,

I work with Fluent and the default $\omega$ treatment at the wall is given by what can be seen in this page.

I need to modify the value of the $\omega$ , which according to several papers can be done with a UDF.

I have checked the available options in the UDF manual, but didn't find a way.

Does anybody here know how this can be done??

Thanks!

David Tyrrell · February 27, 2024, 11:41

Hello,

I am trying to achieve the same thing you were. Essentially I need to modify the value of omega at the wall to model the effect of sharkskin riblet drag reduction.

Did you ever manage to get a result in the end? Or if anyone else could offer advice that would be great, even if it were to say it is not possible in FLUENT.

Regards,
David Tyrrell

HHOS · March 11, 2024, 05:03

At the moment I am not actively developing the udf, but the last status is that I could set a constant omega in the whole domain.

I don't manage to fix it only at the first cell adjacent to certain walls...

Also managed to calculate the u*, which took me some time because I couldn't obtain the wall shear values of each cell ...

February 14, 2024, 12:35	Omega wall treatment change via UDF	#1
HHOS Member Join Date: Jul 2013 Posts: 85 Rep Power: 13	Hello, I work with Fluent and the default $\omega$ treatment at the wall is given by what can be seen in this page. I need to modify the value of the $\omega$ , which according to several papers can be done with a UDF. I have checked the available options in the UDF manual, but didn't find a way. Does anybody here know how this can be done?? Thanks!

February 27, 2024, 11:41	K-Omega UDF - Modelling drag reduction effect by Sharkskin	#2
David Tyrrell New Member David Tyrrell Join Date: Feb 2024 Posts: 1 Rep Power: 0	Hello, I am trying to achieve the same thing you were. Essentially I need to modify the value of omega at the wall to model the effect of sharkskin riblet drag reduction. Did you ever manage to get a result in the end? Or if anyone else could offer advice that would be great, even if it were to say it is not possible in FLUENT. Regards, David Tyrrell

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March 11, 2024, 05:03		#3
HHOS Member Join Date: Jul 2013 Posts: 85 Rep Power: 13	At the moment I am not actively developing the udf, but the last status is that I could set a constant omega in the whole domain. I don't manage to fix it only at the first cell adjacent to certain walls... Also managed to calculate the u*, which took me some time because I couldn't obtain the wall shear values of each cell ...