How can I modify the wall functions?

dunapkt · July 25, 2024, 06:41

Hi all,

I'm new to SU2 and now I'm trying to modify the standard wall function.

I know that I can modify the constants such as kappa (von karman constant), B, etc., in the .cfg file.

But what I want to do is add terms that include a function of y_plus.

For example,

u+ = 1/kappa * log(y_plus) + B +f(y_plus)

For this reason, I tried to find the source code defining the wall functions but I couldn't found it.

Where can I see the exact formula of the wall functions that SU2 uses? Also, is this modification possible in SU2?

Thanks.

Best regards,

bigfootedrockmidget · July 25, 2024, 18:25

What is the physics behind it? Is it for rough walls?

You can see the implementation for the incompressible solver in:
CIncNSSolver::Set_Tau_Wall_WF

The implementation is based on the paper of Nichols and Nelson:
https://arc.aiaa.org/doi/abs/10.2514/1.3539

You can see there that the wall function is implemented implicitly, so we have y+(u+) given by Spalding's formula.

Hope this helps. For more coding help, you can also consider joining our slack channel.If you go to our main website, just click the "Dev Team Slack" option.

https://su2code.github.io/

July 25, 2024, 06:41	How can I modify the wall functions?	#1
dunapkt New Member Join Date: Sep 2022 Posts: 19 Rep Power: 4	Hi all, I'm new to SU2 and now I'm trying to modify the standard wall function. I know that I can modify the constants such as kappa (von karman constant), B, etc., in the .cfg file. But what I want to do is add terms that include a function of y_plus. For example, u+ = 1/kappa * log(y_plus) + B +f(y_plus) For this reason, I tried to find the source code defining the wall functions but I couldn't found it. Where can I see the exact formula of the wall functions that SU2 uses? Also, is this modification possible in SU2? Thanks. Best regards,

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July 25, 2024, 18:25		#2
bigfootedrockmidget Senior Member bigfoot Join Date: Dec 2011 Location: Netherlands Posts: 676 Rep Power: 21	What is the physics behind it? Is it for rough walls? You can see the implementation for the incompressible solver in: CIncNSSolver::Set_Tau_Wall_WF The implementation is based on the paper of Nichols and Nelson: https://arc.aiaa.org/doi/abs/10.2514/1.3539 You can see there that the wall function is implemented implicitly, so we have y+(u+) given by Spalding's formula. Hope this helps. For more coding help, you can also consider joining our slack channel.If you go to our main website, just click the "Dev Team Slack" option. https://su2code.github.io/