Initial data for perturbU

leonardo.morita · April 24, 2009, 05:56

Hello,

I'm going to work with LES and was told to start studying the cyclic channel case. I ran the tutorial and now I'm interested on testing the perturbU utility. However, I didn't find any information about the entries that are needed, other than the Retau in the transportProperties, so I'd like to know if somebody could explain how I can control the perturbations and how the files U, p etc( in the 0 folder) must be initialized (with arbitrary conditions?).

Thank you,

Leo

cedric_duprat · April 24, 2009, 07:45

Hi Leo,

The point is that you don't need other information. And, because Retau is used to define the amplitude of the noise, you can choose it arbitrary.

Check on the LES thread for reference paper of this tool (Schoppa and Hussain Fluid Dynamics Research 2001). Eugene de Villier Ph'd is still really good to get information for LES with OpenFOAM.

Then, you can have a look at the implementation, you don't need to be a C++ expert to get it. The main idea is to add a decreasing sinusoidal random noise to a parabolique profile for the velocity.

I hope It will help.

Cedric.

PS: for more information about LES channel flow, you can have a look there http://openfoamwiki.net/index.php/Si...ion_test_cases
and maybe add some usefull information for the community.

leonardo.morita · April 24, 2009, 08:28

Thank you Cedric,

But should I have something (U, p etc) in the 0 folder before running perturbU? Or these files will be created by the application?

Leo

leonardo.morita · April 24, 2009, 08:55

Forget it...I realized that what I need to do is just to have an U file there, with an arbitrary profile (for example, a zero-velocity field)...

April 24, 2009, 05:56	Initial data for perturbU	#1
leonardo.morita Member Leonardo Giampani Morita Join Date: Apr 2009 Location: Paris, France Posts: 58 Rep Power: 17	Hello, I'm going to work with LES and was told to start studying the cyclic channel case. I ran the tutorial and now I'm interested on testing the perturbU utility. However, I didn't find any information about the entries that are needed, other than the Retau in the transportProperties, so I'd like to know if somebody could explain how I can control the perturbations and how the files U, p etc( in the 0 folder) must be initialized (with arbitrary conditions?). Thank you, Leo

April 24, 2009, 07:45		#2
cedric_duprat Senior Member Cedric DUPRAT Join Date: Mar 2009 Location: Nantes, France Posts: 195 Rep Power: 17	Hi Leo, The point is that you don't need other information. And, because Retau is used to define the amplitude of the noise, you can choose it arbitrary. Check on the LES thread for reference paper of this tool (Schoppa and Hussain Fluid Dynamics Research 2001). Eugene de Villier Ph'd is still really good to get information for LES with OpenFOAM. Then, you can have a look at the implementation, you don't need to be a C++ expert to get it. The main idea is to add a decreasing sinusoidal random noise to a parabolique profile for the velocity. I hope It will help. Cedric. PS: for more information about LES channel flow, you can have a look there http://openfoamwiki.net/index.php/Si...ion_test_cases and maybe add some usefull information for the community. songwukong likes this.

April 24, 2009, 08:28		#3
leonardo.morita Member Leonardo Giampani Morita Join Date: Apr 2009 Location: Paris, France Posts: 58 Rep Power: 17	Thank you Cedric, But should I have something (U, p etc) in the 0 folder before running perturbU? Or these files will be created by the application? Leo Last edited by leonardo.morita; April 24, 2009 at 08:52.

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April 24, 2009, 08:55		#4
leonardo.morita Member Leonardo Giampani Morita Join Date: Apr 2009 Location: Paris, France Posts: 58 Rep Power: 17	Forget it...I realized that what I need to do is just to have an U file there, with an arbitrary profile (for example, a zero-velocity field)...