CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

PostChannel utility not working in OpenFoam 15

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree3Likes
  • 1 Post By lakeat
  • 1 Post By fs82
  • 1 Post By fs82

Reply
 
LinkBack Thread Tools Display Modes
Old   August 14, 2008, 23:49
Default Hi forum... I was trying t
  #1
Senior Member
 
Nishant
Join Date: Mar 2009
Location: Glasgow, UK
Posts: 165
Rep Power: 8
nishant_hull is on a distinguished road
Hi forum...

I was trying to get the postchannel plots for the channel395 case in OF-1.5. Unfortunately postChannel utility has not been able to generate the Uf.xy, u.xy etc etc plots in OF-1.5.

I noticed that instead of Umean, now OF-1.5 writes UMean (capital M) in every time directory. Also R file is not present in time directory. Is this error in postChannel utility because of that? I go through both the codes and find no difference. I am still looking into it but It will be helpful if someone can tell me fast.

regards,
Nishant
__________________
Thanks and regards,

Nishant
nishant_hull is offline   Reply With Quote

Old   August 20, 2008, 22:14
Default can anyone take out some time
  #2
Senior Member
 
Nishant
Join Date: Mar 2009
Location: Glasgow, UK
Posts: 165
Rep Power: 8
nishant_hull is on a distinguished road
can anyone take out some time to comment on the above problem. I changed the postchannel utility with UMean instead of Umean.. and now the utility is complaining about R file not found.
Now the question is, why channeloodle utility is not writting R field??
__________________
Thanks and regards,

Nishant
nishant_hull is offline   Reply With Quote

Old   May 5, 2009, 05:27
Default
  #3
Member
 
Leonardo Giampani Morita
Join Date: Apr 2009
Location: Paris, France
Posts: 58
Rep Power: 8
leonardo.morita is on a distinguished road
Hello,

I have the same problem...after running the postChannel utility, no files are created...has somebody figured out what the cause of the problem is?

Thanks,

Leonardo
leonardo.morita is offline   Reply With Quote

Old   May 6, 2009, 20:48
Default
  #4
Senior Member
 
lakeat's Avatar
 
Daniel WEI (老魏)
Join Date: Mar 2009
Location: South Bend, IN, USA
Posts: 688
Blog Entries: 9
Rep Power: 12
lakeat is on a distinguished road
Send a message via Skype™ to lakeat
  1. As I remember, R is the same as UPrime2Mean
  2. Many of us, would rewrite postChannel utility a bit to get what we need, just search the forum and spend some time to work it out.
babakflame likes this.
__________________
~
Daniel WEI
-------------
NatHaz Modeling Laboratory
Department of Civil & Environmental Engineering & Earth Sciences
University of Notre Dame, USA
Email || My Personal CFD Blog
lakeat is offline   Reply With Quote

Old   June 8, 2009, 04:44
Default
  #5
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
UPrime2Mean is not R I guess. Nevertheless you have to use UPrime2Mean to calculate the reynolds stresses.
fs82 is offline   Reply With Quote

Old   June 8, 2009, 04:49
Default
  #6
Senior Member
 
lakeat's Avatar
 
Daniel WEI (老魏)
Join Date: Mar 2009
Location: South Bend, IN, USA
Posts: 688
Blog Entries: 9
Rep Power: 12
lakeat is on a distinguished road
Send a message via Skype™ to lakeat
Quote:
Originally Posted by fs82 View Post
UPrime2Mean is not R I guess. Nevertheless you have to use UPrime2Mean to calculate the reynolds stresses.
Then, their differences are???
__________________
~
Daniel WEI
-------------
NatHaz Modeling Laboratory
Department of Civil & Environmental Engineering & Earth Sciences
University of Notre Dame, USA
Email || My Personal CFD Blog
lakeat is offline   Reply With Quote

Old   June 8, 2009, 05:29
Default
  #7
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
Allright I think the following, but this is just an assumption, not proved up to now:

R = average(u'_i u'_j)
UprimeToMean = average(u_i u_j)

An by this R becomes:

R = average ( u'_i u'_j) = average(u_i u_j) - average(u_i) * average (u_j) (1)

Edit: I found a working postChannel in the GIT repository. But I am still 99% sure, that R is not the same als Uprime2Mean, if R is the reynolds stress tensor. But I am not able to figure out where the calculation (see equation 1) is done so far. But I am not so familiar with C++, so it is a bit difficult for me to understand the source code :-/ Please correct me if I am wrong.

Last edited by fs82; June 8, 2009 at 10:34. Reason: new awarenesses
fs82 is offline   Reply With Quote

Old   June 9, 2009, 05:32
Default
  #8
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
Mea culpa :-/ I went into the fieldAverage routines and checked the calculation of the reynolds stresses and I have to take back everything and state the opposite. OpenFoam calculates average(u_i u_j) but writes out everytime step average(u'_i u'_j). This is done by equation (1). But before calculation the new reynolds stress tensor equation (1) is used again to get average(u_i u_j) from average(u'_i u'_j). So everything is fine and you can use UPrimeToMean instead of R from former OpenFoam versions.

Sry,
fs82
fs82 is offline   Reply With Quote

Old   June 9, 2009, 05:43
Default
  #9
Senior Member
 
lakeat's Avatar
 
Daniel WEI (老魏)
Join Date: Mar 2009
Location: South Bend, IN, USA
Posts: 688
Blog Entries: 9
Rep Power: 12
lakeat is on a distinguished road
Send a message via Skype™ to lakeat
__________________
~
Daniel WEI
-------------
NatHaz Modeling Laboratory
Department of Civil & Environmental Engineering & Earth Sciences
University of Notre Dame, USA
Email || My Personal CFD Blog
lakeat is offline   Reply With Quote

Old   December 9, 2011, 14:11
Default FieldAveraging-Reynolds stress
  #10
Member
 
pooyan
Join Date: Nov 2011
Posts: 62
Rep Power: 5
sam1364 is on a distinguished road
Hey guys,

I am trying to get Reynolds Stress Components for Lid driven cavity flow. By using fieldaveraging, I get 6 components for uprime2mean as written below

UPrime2Mean:0
UPrime2Mean:1
UPrime2Mean:2
UPrime2Mean:3
UPrime2Mean:4
UPrime2Mean:5

My questions are that, are these components the Reynolds Stress tensor?!
Which of these representing <uu>, <uv>, <vv> and etc?!


Thanks
sam1364 is offline   Reply With Quote

Old   December 11, 2011, 07:37
Default
  #11
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
Hey,

have a look for example at this page http://www.foamcfd.org/Nabla/guides/...sGuidese4.html.
fs82 is offline   Reply With Quote

Old   December 12, 2011, 15:36
Default
  #12
Member
 
pooyan
Join Date: Nov 2011
Posts: 62
Rep Power: 5
sam1364 is on a distinguished road
Thanks. I went through this website, but I could not get any help from that. Do you think these six components are Reynolds Stress tensor?!

I guess Uprime2Mean (0) is <uu> and Uprime2Mean (1) is <vv>
sam1364 is offline   Reply With Quote

Old   December 13, 2011, 05:26
Default
  #13
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
Alright, the site I suggested wasn't the best one to read. The best way is to try it out. I guess you have performed a test run and already have the field "UPrime2Mean". So do the following: "foamCalc components UPrime2Mean" in your foam case directory. This will provide you each component uu, vv, ww, uv, uw, vw in a separate file. Compare the values of your original symmTensor field to the ones in the files and you have the answer.
For my understanding UPrime2Mean represents more or less the Reynolds stresses. If you perform an LES you have:
Mean Value + Fluctuations + Subgrid stresses = Instantaneous value
and UPrime2Mean include for my understanding only the Fluctuations. In case of RANS I am not sure, but I think UPrime2Mean does not exist there (never tried a RANS), but you got an additional field named R, which represents the Reynolds stresses. May be one of the more advanced user could give you more information.

kind regards,
Fabian
sam1364 likes this.
fs82 is offline   Reply With Quote

Old   December 13, 2011, 17:58
Default
  #14
Member
 
pooyan
Join Date: Nov 2011
Posts: 62
Rep Power: 5
sam1364 is on a distinguished road
Thanks for your complete response. I do appreciate your help.
I will try those suggested ways.


Best Wishes,
sam1364 is offline   Reply With Quote

Old   January 17, 2012, 17:39
Default
  #15
Member
 
pooyan
Join Date: Nov 2011
Posts: 62
Rep Power: 5
sam1364 is on a distinguished road
Fabian,

I tried to get access to the source code to check the calculation of UPrime2Mean. I went through fieldAverage.C and fieldAverage.H, but unfortunately I could not see the calculation of Uprime2Mean in those files. Where should I check that out?

Thanks,



Quote:
Originally Posted by fs82 View Post
Alright, the site I suggested wasn't the best one to read. The best way is to try it out. I guess you have performed a test run and already have the field "UPrime2Mean". So do the following: "foamCalc components UPrime2Mean" in your foam case directory. This will provide you each component uu, vv, ww, uv, uw, vw in a separate file. Compare the values of your original symmTensor field to the ones in the files and you have the answer.
For my understanding UPrime2Mean represents more or less the Reynolds stresses. If you perform an LES you have:
Mean Value + Fluctuations + Subgrid stresses = Instantaneous value
and UPrime2Mean include for my understanding only the Fluctuations. In case of RANS I am not sure, but I think UPrime2Mean does not exist there (never tried a RANS), but you got an additional field named R, which represents the Reynolds stresses. May be one of the more advanced user could give you more information.

kind regards,
Fabian
sam1364 is offline   Reply With Quote

Old   January 18, 2012, 06:26
Default
  #16
Senior Member
 
Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 180
Rep Power: 8
fs82 is on a distinguished road
You have to go to the follwing directory: <foampath>/OpenFOAM-1.6.x/src/postProcessing/functionObjects/field/fieldAverage/fieldAverage and everything is there. The calculation of the mean and Prime2Mean values could be found in fieldAverageTemplates.C after a quick look.

hope this helps,
Fabian
sam1364 likes this.
fs82 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
OpenFOAM Message Board Email notification stopped working mbeaudoin OpenFOAM Bugs 3 January 8, 2009 23:08
Mathematical exact definition of mesh quality measures in OpenFOAM checkMesh utility albcem OpenFOAM Meshing Format & General Technical 1 October 31, 2008 05:12
PostChannel Utility in openfoam15 not working nishant_hull OpenFOAM Bugs 0 August 14, 2008 15:49
My OpenFoam stop working can anyone help please qtian OpenFOAM Running, Solving & CFD 0 February 19, 2008 17:55
OpenFOAM is working for this nobody_ua OpenFOAM Running, Solving & CFD 4 April 20, 2005 06:11


All times are GMT -4. The time now is 01:02.