
[Sponsors] 
July 20, 2006, 08:52 
Could somebody tell me what ar

#1 
Member
Dihao Tang
Join Date: Mar 2009
Posts: 78
Rep Power: 10 
Could somebody tell me what are the values of Sutherland coefficient As and Sutherland temperature Ts for air? Thanks!


July 20, 2006, 13:04 
For viscosity:
mu=1.4584E6*p

#2 
New Member
mbark elmorsli
Join Date: Mar 2009
Location: Sherbrooke, quebec, canada
Posts: 1
Rep Power: 0 
For viscosity:
mu=1.4584E6*pow(T,3./2.)/(T+110.33); and for thermal conductivity: lambda=2474.7264e6*pow(T,3./2.)/(T+194.4) 

July 26, 2006, 01:21 
Thanks for your reply. What ar

#3 
Member
Dihao Tang
Join Date: Mar 2009
Posts: 78
Rep Power: 10 
Thanks for your reply. What are the coefficients As and Ts for N2? Is there a table including the coefficient of all gases?


July 24, 2009, 05:29 
Where to define the conductivity?

#4 
New Member
Tom Potters
Join Date: Jul 2009
Posts: 14
Rep Power: 10 
When using constTransport the conductivity can be calculated based on the viscosity, the heat capacity and the Prandtl number. When using sutherlandTransport there is no mention of the conductivity constant (at least not in the manual). You also give the sutherland coefficients for the conductivity, but then my question is where do I use them? Right after those of the viscosity?


October 26, 2012, 04:24 

#5 
New Member
mohsen cheraghi
Join Date: Jun 2010
Location: Switzerland
Posts: 28
Rep Power: 9 
I have the same question. can any one explain more?


October 30, 2012, 06:05 

#6 
New Member
Join Date: Oct 2011
Posts: 19
Rep Power: 7 
I am also interested in the calculation of the thermal conductivity. Is there any more information? Which numbers in the second equation are coefficients, that I have to set in OpenFOAM? Hope anyone can help us!


December 6, 2012, 08:00 

#7 
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,210
Rep Power: 19 
I don't think conductivity coefficients to be necessary.only As and Ts are important.


April 23, 2013, 16:37 

#8 
Member
Camille
Join Date: Oct 2012
Posts: 54
Rep Power: 6 
Hi,
could you tell me where I can find the sutherland coefficients As and Ts for natural gas (ie: methane). And where can I find a table of these coef. for any gas? Thank you very much 

April 3, 2014, 10:20 

#9 
New Member
Join Date: Dec 2013
Posts: 11
Rep Power: 5 
Hej everyone!
Sorry for reactivating this old post, but it is still not clear to me how the thermal conductivity is calculated by OF when using Sutherland's law. For my calculations I use chtMultiRegionSimpleFoam (OF 2.2.x) and experimented with the transport models in thermophysicalProperties of a fluid region. The thermo model I set is heRhoThermo and the fluid is air. When I set transport to "const", I define a constant dynamic viscosity mu and the Prandtl number Pr. The thermal conductivity k is then calculated by Pr=mu*cp/k. In a second example I set transport to "sutherland". Now I define only the two input parameters As=1.4792e06 and Ts=116 for Sutherland's law. Since there is no error message when starting a calculation, I guess that no other input is needed. But how does the solver calculate the thermal conductivity then? Thank you for any help, Daniel 

July 16, 2014, 15:46 

#10  
Member
Brock Lee
Join Date: Sep 2012
Location: Midwest
Posts: 38
Rep Power: 7 
Quote:
The OpenFOAM sutherland viscosity model appears to use the modified Euken Model (based on kinetic theory) for the thermal conductivity calculation. I found the equation being used on line 149 of the sutherlandTransportI.H file ($FOAM_SRC/thermophysicalModels/specie/transport/sutherland/sutherlandTransportI.H) I identified it as the modified Euken Model based on section 1.4.7.2.2 of this doc... http://www.arc.vt.edu/ansys_help/cfx_mod/i1299744.html Brock 

July 18, 2014, 06:00 

#11 
New Member
Join Date: Dec 2013
Posts: 11
Rep Power: 5 
Hej Brock!
Thank you very much for your precise answer! I think you are right, the solver uses the modified Eucken equation in order to calculate the thermal conductivity if the Sutherland transport model is selected. However, I am not sure how good the accuracy of this model is? From what I read, the thermal conductivity calculated from the modified Eucken equation differs up to 25% from experimental values. Anyway, the accuracy is another question. It is good to know what OpenFOAM does! Thanks again for your help! Daniel 

November 3, 2015, 09:38 

#12 
New Member
Join Date: Sep 2015
Posts: 15
Rep Power: 4 
Sorry if I'm witless but I can't understand how to get As and Ts from mu and lambda equations posted at the top of the thread! In particular in my case I'm interested in values for air.
Thanks for your help. Alessandro 

November 18, 2015, 10:00 

#13  
New Member
Alexey Ryakhovskiy
Join Date: Sep 2014
Posts: 6
Rep Power: 5 
Quote:
As = 1.4584E6 Ts = 110.33 

November 23, 2015, 16:12 
Thermal conductivity for each species

#14 
New Member
Younis Najim
Join Date: Apr 2013
Location: Michigan State University
Posts: 11
Rep Power: 6 
Hi,
Does anybody know how to include thermal conductivity of individual species (not for mixture) in the Fluent results. I know how to get Cp and species gradients but still struggling with thermal conductivity. Thank you in advance 

April 10, 2016, 08:00 
As and Ts in methan combustion

#15 
Member
amin jalalian
Join Date: Mar 2014
Posts: 34
Rep Power: 5 
Hi
I am working with methaneair 2step combustion. In later versions of openfoam there was no need to file 'transportProperties' but in openfoam3.0+ there is need to that. In openfoam3.0+ tutorial in 'transportProperties' it was As and Ts. What values must I write for these parameters in methane combustion? 

September 13, 2017, 13:00 
Alternative for broken link

#16  
New Member
Eric Bringley
Join Date: Nov 2016
Posts: 3
Rep Power: 2 
Quote:
CFX Documentation: https://www.sharcnet.ca/Software/Ans...cfx_intro.html Specifically: https://www.sharcnet.ca/Software/Ans.../i1299744.html 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
B.C. setting  PK  FLUENT  0  September 28, 2007 03:46 
1way FSI Setting  lars  CFX  0  June 18, 2007 07:06 
Setting up a FAN  BEN  FLUENT  0  March 25, 2006 23:36 
BC setting  Richard  CFX  1  March 20, 2006 11:49 
Setting relaxationsfactors  Phil  FLUENT  6  July 31, 2000 05:01 