Apperance of mysterious He while trying to run reactingFoam solver

mukundvgupta · January 11, 2021, 20:41

Dear Community,

I have been experiencing the appearance of mysteriously high amount of He concentration while trying to run reactingFoam solver under counterFlowDiffusionFlame2D case. This issue became predominant when I moved from OpenFOAM version 5 to version 7. I am trying to model hydrogen-oxygen combustion. Does anyone have any idea why this might be happening?

dlahaye · January 12, 2021, 03:47

Does He appear as a species to repair mass conservation?

That is, does reactingFoam solve for N-1 species, where N is the amount of species in the reaction mechanism?

Does the amount of He decrease/increase by changing the accurary of the time-stepping procedure, either by changing the time step or by changing the accuracy (atol and troll values) that govern the time step?

Gerry Kan · January 12, 2021, 04:45

Dear Mukund:

I looks like He is your inert species, as I see that it is being used a complement so that all mass fractions add up to one. If the amount of helium is not important, I would suggest leaving your chemistry set up as-is.

Hope that helps, Gerry.

mukundvgupta · January 21, 2021, 21:07

Hi Gerry,

Thanks for your suggestion. Yes, He is being used so that all mass fractions add to 1. I am afraid I cannot leave the chemistry as it is because having some amount of He is important for the simulation I am trying to do.

Do you have any other suggestion in mind that I can use?

mukundvgupta · January 21, 2021, 21:09

Dear dlahaye,

Thanks for the suggestion, I will try this out and let you know what I am able to find?

January 12, 2021, 04:45		#3
Gerry Kan Senior Member Gerry Kan Join Date: May 2016 Posts: 347 Rep Power: 10	Dear Mukund: I looks like He is your inert species, as I see that it is being used a complement so that all mass fractions add up to one. If the amount of helium is not important, I would suggest leaving your chemistry set up as-is. Hope that helps, Gerry. Last edited by Gerry Kan; January 12, 2021 at 08:45.

January 21, 2021, 21:09		#5
mukundvgupta New Member Mukund Gupta Join Date: Jan 2021 Posts: 3 Rep Power: 5	Dear dlahaye, Thanks for the suggestion, I will try this out and let you know what I am able to find? dlahaye likes this.

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January 12, 2021, 03:47		#2
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 722 Blog Entries: 1 Rep Power: 17	Does He appear as a species to repair mass conservation? That is, does reactingFoam solve for N-1 species, where N is the amount of species in the reaction mechanism? Does the amount of He decrease/increase by changing the accurary of the time-stepping procedure, either by changing the time step or by changing the accuracy (atol and troll values) that govern the time step?

January 21, 2021, 21:07		#4
mukundvgupta New Member Mukund Gupta Join Date: Jan 2021 Posts: 3 Rep Power: 5	Hi Gerry, Thanks for your suggestion. Yes, He is being used so that all mass fractions add to 1. I am afraid I cannot leave the chemistry as it is because having some amount of He is important for the simulation I am trying to do. Do you have any other suggestion in mind that I can use?