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

how to get Sutherland and JANAF coefficients of air?

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

Like Tree2Likes

Reply
 
LinkBack Thread Tools Display Modes
Old   December 4, 2012, 13:34
Default how to get Sutherland and JANAF coefficients of air?
  #1
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
I want to use function of time values of viscosity and Cp.where can I find the proper values?
immortality is offline   Reply With Quote

Old   December 5, 2012, 02:45
Default
  #2
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
is there a useful document about it?i can't find anything.
immortality is offline   Reply With Quote

Old   December 5, 2012, 04:19
Default
  #3
Member
 
Join Date: Nov 2010
Location: Tokyo / Japan
Posts: 40
Rep Power: 6
Hanzo is on a distinguished road
Did you try this?

books:
https://www.google.com/search?client...w=1920&bih=968

if you are lucky you may find a free article or can access from your institution
http://scholar.google.com/scholar?q=...ed=0CCwQgQMwAA
Hanzo is offline   Reply With Quote

Old   December 5, 2012, 11:23
Default
  #4
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
Ididn't find a useful free one.
immortality is offline   Reply With Quote

Old   December 5, 2012, 12:08
Default
  #5
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
ofcourse I have some tables but I don't know how to use it for getting a useful numbers for importing in openfoam.another is that what componet i should use? N2 return to airis good?
immortality is offline   Reply With Quote

Old   December 5, 2012, 18:52
Default
  #6
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
dear friends I found the coefficients of exactly air not even nitrogen in the new format and found how to use it at old format that openfoam uses.its in openfoamwiki website but not clear.in fact a3.a4...a9 in new format are a1...a7 in old format that as i told openfoam uses.
If anyone wants the coeficients or more explanations feel free to say.
immortality is offline   Reply With Quote

Old   February 22, 2013, 17:55
Default
  #7
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
I would like to have more informations about the coefficients. Can I have your thermoPhysicalProperties file? To see how you write this

If you have more explanations about this, I'm also interested.

Thank you for your help
vwibaut is offline   Reply With Quote

Old   February 23, 2013, 04:15
Default
  #8
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
hi
Ok i'll send it soon.
immortality is offline   Reply With Quote

Old   February 23, 2013, 13:43
Default
  #9
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
I've set .75N2 and .25O2 and have obtain this coefficient by MATLAB.
Code:
thermoType      hPsiThermo<pureMixture<sutherlandTransport<specieThermo<janafThermo<perfectGas>>>>>;

mixture
{
    specie
    {
        nMoles          1;
        molWeight       28.96;
    }
    thermodynamics
    {
     Tlow 200;
     Thigh 6000;
     Tcommon 1000;
     highCpCoeffs (3.129672277499967 1.211766752750042e-3 -4.04761109000018e-7 6.409571300000324e-11 -3.780447620000211e-15 -1.190120342415573e3 5.2577564125);
     lowCpCoeffs  (3.593868050000014 -8.419292810001117e-4 2.08457592775033e-6 -5.938441825004294e-10 -2.456771699998039e-13 -1.053301888245469e3 3.1400217175);
        /*Cp              1040;
        Hf              2.544e+06;*/
    }
    transport
    {
       As 1.4584e-6;
       Ts 110.4;
        /*mu              1.84e-05;
        Pr              0.75;*/
    }
}
immortality is offline   Reply With Quote

Old   February 24, 2013, 06:13
Default
  #10
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
Thank you very much ehsan

I have a question: why do you use N2 75% and O2 25%? Air has approximately 79% N2 and 21% O2.

How do you find the coefficients with matlab?
vwibaut is offline   Reply With Quote

Old   February 24, 2013, 07:04
Default
  #11
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
you're welcome valentin
I think i used those coefficients you said at last.i'll see the Matlab m-file and let you know about it.
I wrote a m-file in matlab.you can find the coefficients of n2 and o2 in openfoamwiki,search for janaf contrib and at the page go to the link for old version of janaf.
Im ready to help you more.
immortality is offline   Reply With Quote

Old   February 24, 2013, 09:26
Default
  #12
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
Thanks for your help
I confirm that you use 0.75 N2 and 0.25 O2

But I have some different values and I don't find the error. I take the coefficient for O2 and N2 in the janaf table (openfoamwiki) like you.

Last edited by vwibaut; February 24, 2013 at 10:23.
vwibaut is offline   Reply With Quote

Old   February 24, 2013, 13:52
Default
  #13
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
I have an other question.
My goal is to simulate the flow in a nozzle, and I would like to take into account the variation of the cp with the temperature altough I think this variation is very small in this case. In the nozzle I can have a temperature of 120K wich is lower thant the Tlow of janaf (200K).
An idea how to solve this problem?
vwibaut is offline   Reply With Quote

Old   February 24, 2013, 14:02
Default
  #14
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
send me your values.i think it can be agreable that you extrapolate since the distance between 160 and 200 is not so high.but you should be certain that this temp is valid because some troubles in solution process may lead to very low or very high values in temperatures.
immortality is offline   Reply With Quote

Old   February 24, 2013, 14:43
Default
  #15
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
Yes I'm sure for the value of the temperature, it's the analytical solution Ok so I have to create a new janafthermo wich interpolate the cp when the temperature is <200K.

For the values, I don't have them here but I will let you know about it. I have the same values except for one or two.
vwibaut is offline   Reply With Quote

Old   February 24, 2013, 19:22
Default
  #16
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
ok.im curious about the different numbers.maybe i have made a mistake.
immortality is offline   Reply With Quote

Old   March 8, 2013, 05:29
Default
  #17
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
could you send you calculated numbers to compare?
immortality is offline   Reply With Quote

Old   March 8, 2013, 05:35
Default
  #18
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
hi,

Sorry, I work in dual boot and the most of the time I can't access to matlab (and so to the coefficients you need). I will give you the coefficients as quickly as possible.
vwibaut is offline   Reply With Quote

Old   March 11, 2013, 06:00
Default my coefficients
  #19
Member
 
Valentin Wibaut
Join Date: Oct 2012
Posts: 45
Rep Power: 4
vwibaut is on a distinguished road
highCpCoeffs (3.129672277499967 1.211766752750042e-3 -4.04761109000018e-7 6.409571300000324e-11 -3.780447620000211e-15 -996.9558 5.2577564125);
lowCpCoeffs (3.593868050000014 -8.419292810001117e-4 2.08457592775033e-6 -5.938441825004294e-10 -2.456771699998039e-13 -1.0512e3 3.1400217175);

It isn't a big difference
vwibaut is offline   Reply With Quote

Old   March 13, 2013, 10:52
Default
  #20
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,186
Rep Power: 16
immortality is on a distinguished road
how did you calculate h and s coefficients?
immortality is offline   Reply With Quote

Reply

Tags
janaf, openfoam, sutherland

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 12:46.