Wall_shear_stress_from_post_util

Questions and remarks about Code_Saturne usage
Forum rules
Please read the forum usage recommendations before posting.
Post Reply
C0st4s
Posts: 43
Joined: Fri May 11, 2018 12:21 pm

Wall_shear_stress_from_post_util

Post by C0st4s » Fri May 31, 2019 7:15 pm

Hi,

Hope you are well.

I would like to ask you how can I perform a time average of the wall shear stress on the vertical wall of a square cavity i.e from the tutorial examples. I know the tangential stress can be called from post_util.f90 and pass the information in the cs_user_extra_operations.f90 in order to print it in a file but I do not know how the indexing corresponds to each component.

Thank you in advance,
Costas

Luciano Garelli
Posts: 225
Joined: Fri Dec 04, 2015 1:42 pm

Re: Wall_shear_stress_from_post_util

Post by Luciano Garelli » Mon Jun 03, 2019 12:36 pm

Hello,

In the file cs_user_extra_operations-global_efforts.f90 there is an exmple how to compute global efforts on a subset of faces. Did you check it?

Regards,

Luciano

C0st4s
Posts: 43
Joined: Fri May 11, 2018 12:21 pm

Re: Wall_shear_stress_from_post_util

Post by C0st4s » Fri Jun 07, 2019 6:14 pm

Dear Luciano,

Thanks for you reply. I will check it though I do not know how valid is that approach if you use standard k-epsilon.


Regards,
Costas

Yvan Fournier
Posts: 2780
Joined: Mon Feb 20, 2012 3:25 pm

Re: Wall_shear_stress_from_post_util

Post by Yvan Fournier » Sat Jun 08, 2019 1:05 pm

Hello,

The efforts in the "global_efforts" example are based on accessing precomputed efforts/stresses, that are computed based on the different term contributions during a time step, so it should be correct with any turbulent model.

Note that when computation of efforts/stresses is activated (for example when requesting their postprocessing output in the GUI), the corresponding values are stored in a field, and you can simply use the field with standard time moment definitions (in the user subroutines, as this may not be accessible yet for boundary time moments).

Best regards,

Yvan

C0st4s
Posts: 43
Joined: Fri May 11, 2018 12:21 pm

Re: Wall_shear_stress_from_post_util

Post by C0st4s » Tue Jun 11, 2019 7:08 pm

Dear Yvan,

Thank you for your reply.
I thought of finding a way to call directly the friction velocities from clptur.f90 i.e rho uk*uk and compute the wall shear stress. I supposed this is from where the code compute the efforts.
Though, is it possible to make a call for the variable uk in that routine and print it out in cs_user_extra_operations.f90 or do I have to declare a user field in the cs_user_parameters.f90?


Thanks,
Costas

Post Reply