reactingFoam non unity Lewis number

lollo15 · April 22, 2021, 11:45

Hello everyone !

I'm new with reactingFoam ( OpenFoam v8) and i'm looking for the option or where set a Lewis number different from 1.

I know that exist the file nonUnityLewisEddyDiffusivity.H that define Sc and Prt so i'm trying to use it instead of the conventional method.

Someone knows how to do it ??

Best regards !
Thank you!

Lorenzo

clapointe · April 22, 2021, 12:33

Checking out the relevant .H file (nonUnityLewis) you'll see the following :

Code:

    LES
    {
        model         nonUnityLewisEddyDiffusivity;
        Prt             0.85;
        Sct             0.7;
    }

This would go into a thermophysicalTransport file (similarly to how you have a momentumTransport file). The description mentions for RAS or LES, so either option should be available. There are a few tutorials that include a thermophysicalTransport file (e.g., https://github.com/OpenFOAM/OpenFOAM...sicalTransport) that could also be helpful.

Caelan

dlahaye · April 23, 2021, 03:52

Wonderful, thx! Can you point to references in which the non-unit Lewis model has been validated?

clapointe · April 23, 2021, 16:20

I've unfortunately not used that functionality, so I'm not familiar if/where it's been used since its release. I imagine, though, that updating the reactingFoam tutorial for the Sandia or DLR flames would be a good place to start, given that the experimental data is readily available.

Caelan

dlahaye · April 25, 2021, 16:13

Thx for your advice on this matter. Best wishes, Domenico.

lollo15 · April 28, 2021, 05:36

Thanks you for the response,

I have another question, the unity of lewis number means also that the Prt is equal to the Sct ?

Best wishes, Lorenzo.

dlahaye · April 28, 2021, 07:15

Yes, affermative, it does. See e.g. the book by Versteeg and Malalasekera, the master thesis of Ali Kadar at https://repository.tudelft.nl/island...tion=education or https://en.wikipedia.org/wiki/Lewis_number among other references.

lollo15 · April 30, 2021, 07:31

Hello

I serch in the code where the Sct is taken equal to the Prt but if the unity Lewis number is imposed the Sct is not considered. Is it mean that Sct is 1?
And if I do not specify the Prt in the momentumTransport file in the KEpsilonCoeffs section, is it take as 1 also ?

Best wishes, Lorenzo.

April 22, 2021, 11:45	reactingFoam non unity Lewis number	#1
lollo15 New Member Lorenzo Join Date: Apr 2021 Posts: 9 Rep Power: 5	Hello everyone ! I'm new with reactingFoam ( OpenFoam v8) and i'm looking for the option or where set a Lewis number different from 1. I know that exist the file nonUnityLewisEddyDiffusivity.H that define Sc and Prt so i'm trying to use it instead of the conventional method. Someone knows how to do it ?? Best regards ! Thank you! Lorenzo

April 22, 2021, 12:33		#2
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 14	Checking out the relevant .H file (nonUnityLewis) you'll see the following : Code: LES { model nonUnityLewisEddyDiffusivity; Prt 0.85; Sct 0.7; } This would go into a thermophysicalTransport file (similarly to how you have a momentumTransport file). The description mentions for RAS or LES, so either option should be available. There are a few tutorials that include a thermophysicalTransport file (e.g., https://github.com/OpenFOAM/OpenFOAM...sicalTransport) that could also be helpful. Caelan lollo15 likes this. __________________ Public git repository : https://github.com/clapointe2011/public

April 23, 2021, 16:20		#4
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 14	I've unfortunately not used that functionality, so I'm not familiar if/where it's been used since its release. I imagine, though, that updating the reactingFoam tutorial for the Sandia or DLR flames would be a good place to start, given that the experimental data is readily available. Caelan dlahaye likes this. __________________ Public git repository : https://github.com/clapointe2011/public

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April 23, 2021, 03:52		#3
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 723 Blog Entries: 1 Rep Power: 17	Wonderful, thx! Can you point to references in which the non-unit Lewis model has been validated?

April 25, 2021, 16:13		#5
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 723 Blog Entries: 1 Rep Power: 17	Thx for your advice on this matter. Best wishes, Domenico.

April 28, 2021, 05:36		#6
lollo15 New Member Lorenzo Join Date: Apr 2021 Posts: 9 Rep Power: 5	Thanks you for the response, I have another question, the unity of lewis number means also that the Prt is equal to the Sct ? Best wishes, Lorenzo.

April 28, 2021, 07:15		#7
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 723 Blog Entries: 1 Rep Power: 17	Yes, affermative, it does. See e.g. the book by Versteeg and Malalasekera, the master thesis of Ali Kadar at https://repository.tudelft.nl/island...tion=education or https://en.wikipedia.org/wiki/Lewis_number among other references.

April 30, 2021, 07:31		#8
lollo15 New Member Lorenzo Join Date: Apr 2021 Posts: 9 Rep Power: 5	Hello I serch in the code where the Sct is taken equal to the Prt but if the unity Lewis number is imposed the Sct is not considered. Is it mean that Sct is 1? And if I do not specify the Prt in the momentumTransport file in the KEpsilonCoeffs section, is it take as 1 also ? Best wishes, Lorenzo.