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

[dsmcFoam] Where is dsmcFieldsCalc executed?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 16, 2011, 02:20
Default [dsmcFoam] Where is dsmcFieldsCalc executed?
  #1
New Member
 
Fabian
Join Date: Jan 2010
Posts: 27
Rep Power: 6
gautcho is on a distinguished road
Hello,

I meanwhile really understand a lot of dsmcFoam, but I can't figure out where the dsmcFieldsCalc-routine is executed? I think, it is somewhere in the time.loop-method, but I cant get any further. Could anybody help me?
gautcho is offline   Reply With Quote

Old   June 16, 2011, 12:29
Default
  #2
New Member
 
Graham Macpherson
Join Date: Mar 2009
Posts: 8
Rep Power: 7
gmacpherson is on a distinguished road
There is no need to run the dsmcFieldsCalc utility if you have the dsmcFields and fieldAverage function objects from the dsmc tutorials in your controlDict.

All that dsmcFieldsCalc does is execute the dsmcFields function object.

Regards,

Graham
gmacpherson is offline   Reply With Quote

Old   June 17, 2011, 03:00
Default
  #3
New Member
 
Fabian
Join Date: Jan 2010
Posts: 27
Rep Power: 6
gautcho is on a distinguished road
Okay, perhaps I should think a little bit about this function-in-controlDict-thing. There also comes another question into my mind: Is the mean-function a standardmean over the last writeIntervall or are there any weights or values from the further writeIntervall (I think this depends on the "resetOnOutput"-param)?

Are you the MacPherson, who implemented MD? Than you could tell me, if I would be right, if Id say, that you implemented MD and Scanlon and other implemented dsmc on the basics you created. Because its not that easy to find this out .
gautcho is offline   Reply With Quote

Old   June 17, 2011, 03:30
Default About "where is"
  #4
New Member
 
Francesca
Join Date: Feb 2011
Posts: 10
Rep Power: 4
Francesca Scaramuzzino is an unknown quantity at this point
Hello, I know that this is not the right place to post this kind of question..anyway..I'm trying to understand the pitzDaily case, in the simpleFoam but in the XiFoam too (for the difference between RAS and LES simulations). So, I've found something about the experiment of Pitz and Daily and in every case I read that the mixture used is propane-air But in the directories I can't find this information. I mean, after the constant values of the variables where I could find the information about the mixture and the composition??

Thanks

Francesca
Francesca Scaramuzzino is offline   Reply With Quote

Old   June 17, 2011, 04:16
Default
  #5
New Member
 
Graham Macpherson
Join Date: Mar 2009
Posts: 8
Rep Power: 7
gmacpherson is on a distinguished road
Hi gautcho,

fieldAverage averages from the start of the simulation (and the averaging survives restarts), unless you have

resetOnOutput on;

in which case it averages between write intervals. This parameter is runtime modifiable, so I normally have it set to 'on' until a case gets to steady state, and switch it to 'off' after to collect and average fields.

Also, yes, I'm the Macpherson of the MD. I implemented the MD as my PhD, and the DSMC was implemented by me at OpenCFD with some discussions and testing by Scanlon et al. The MD and DSMC were both implemented on the basics that were already in OpenFOAM (i.e particle tracking).

Graham
gmacpherson is offline   Reply With Quote

Old   June 17, 2011, 07:33
Default
  #6
New Member
 
Fabian
Join Date: Jan 2010
Posts: 27
Rep Power: 6
gautcho is on a distinguished road
Oh,

thats nice. Thank you for the solver . I'm writing my diploma thesis about DSMC, dsmcFoam and some applications and I'm working my way through your code right now. If its okay for you, I would ask you some more questions.

1. Biggest at the moment: Where does the post-collision-velocity in the VHS-model come from? I found some similar formular in the Bird (page 36, formulas 2.22), but they are not the same, I think. And why do you use a randomly found angle?

2. Where does the 3rd-velocity-component after collision in MaxwellianThermal come from?
sqrt(-2.0*log(max(1 - rndGen.scalar01()

Its quote similar too the gaussNormal, but I cant get the real difference. Is it from Shen?

3. In which part of the code are particles able to disappear? As far as I can see only in the trackToFace-method, if they hit a patch and then they get deleted in the deleteParticle-method in Cloud.C. Problem: I made some screenprompts at any time deleteParticle is used, but the number of deleted particles in most of the times was higher than the number of screenprompts. If I switch of the possibility to disappear via "hit patch", than every particle stays in the volume. Where does this difference come from?

4. In variableHardSphere.C you used 4.79 from Bird, but I cant figure out what the exp in your implementation does (line 94)?

Last edited by gautcho; June 17, 2011 at 08:52.
gautcho is offline   Reply With Quote

Old   June 17, 2011, 07:38
Default About pitzDaily
  #7
New Member
 
Francesca
Join Date: Feb 2011
Posts: 10
Rep Power: 4
Francesca Scaramuzzino is an unknown quantity at this point
Hello,
I'm trying to understand the pitzDaily case, in the simpleFoam but in the XiFoam too (for the difference between RAS and LES simulations). So, I've found something about the experiment of Pitz and Daily and in every case I read that the mixture used is propane-air. Anyway in the directories I can't find this information. I mean, after the constant values of the variables where I could find the information about the mixture and the composition?

Thanks

Francesca
Francesca Scaramuzzino is offline   Reply With Quote

Old   June 23, 2011, 09:30
Default
  #8
New Member
 
Fabian
Join Date: Jan 2010
Posts: 27
Rep Power: 6
gautcho is on a distinguished road
Quote:
Originally Posted by gautcho View Post
Oh,

thats nice. Thank you for the solver . I'm writing my diploma thesis about DSMC, dsmcFoam and some applications and I'm working my way through your code right now. If its okay for you, I would ask you some more questions.

1. Biggest at the moment: Where does the post-collision-velocity in the VHS-model come from? I found some similar formular in the Bird (page 36, formulas 2.22), but they are not the same, I think. And why do you use a randomly found angle?

2. Where does the 3rd-velocity-component after collision in MaxwellianThermal come from?
sqrt(-2.0*log(max(1 - rndGen.scalar01()

Its quote similar too the gaussNormal, but I cant get the real difference. Is it from Shen?

3. In which part of the code are particles able to disappear? As far as I can see only in the trackToFace-method, if they hit a patch and then they get deleted in the deleteParticle-method in Cloud.C. Problem: I made some screenprompts at any time deleteParticle is used, but the number of deleted particles in most of the times was higher than the number of screenprompts. If I switch of the possibility to disappear via "hit patch", than every particle stays in the volume. Where does this difference come from?

4. In variableHardSphere.C you used 4.79 from Bird, but I cant figure out what the exp in your implementation does (line 94)?
Does anybody else know some answers?
gautcho is offline   Reply With Quote

Old   February 7, 2014, 22:37
Default localMn, localMfp, localCf, localCh are missing from dsmcfoam results
  #9
New Member
 
reji
Join Date: Nov 2011
Posts: 8
Rep Power: 4
rejirv is on a distinguished road
Hello sir,
Previously there are more variable as results from dsmcfoam such as localMn, localMfp, localCf, localCh etc. But now it seems to be missing.

Any suggestions to obtain those variables ?
Thank you
rejirv 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



All times are GMT -4. The time now is 07:48.