Learning Forum

[abtharpe42]

I'm using the 2024 R1 release of Fluent and a paper that I've been reading through says they used Flamelet Generated Manifold to simulate fully-premixed combustion, which I really want to use to handle the GRI Mech 3.0 mechanism. The 2024 R1 user guide shows that there is an option that explicitly states "Fully Premixed FGM" under the "Flamelet" tab in the Partially Premixed Combustion Model as shown below:

The problem is that when I pull up the model in Fluent myself, the option is not there at all even with "Premixed Flamelet" selected under the "Chemistry" tab:

The user guide doesn't explain how the option appears in the menu. How do I make the "Fully Premixed FGM" option appear like the user guide?

 

[Essence]

Hello,

Try selecting non-adiabatic option before turning to Flamelet tab. Then select CHEMKIN physical space and then Flamelet tab. There, turn ON Nonadiabatic Flamelets. You will observe Full Premixed FGM option.

[abtharpe42]

Okay, i got it to appear. I turned off P1 radiation and opened up a fresh FGM setup window. Having a radiation model enabled before opening up the setup menu was locking in the Non-Adiabatic option on the Chemistry tab and not letting me choose Adiabatic. Then I moved over to the Flamelet tab and was able to choose the Nonadiabatic Flamelets and Fully Premixed FGM options. Thanks!

[abtharpe42]

Now I have some followup questions. Let's say I want to use a stoichiometric fully premixed mixture of hydrogen and air. The stoichimetric mixture fraction is about 0.0285. For the Fully Premixed FGM setup, would I type 0.0285 in the blank for "Mixture Fraction Value for Flamelet Generation" and then generate the tables? 

After that, would I input 0.0285 in the "Mean Mixture Fraction" blank at my inlet boundary conditon (5 m/s)? Doing this and eventually patching a progress variable of 1 over the whole 2d pipe domain yielded these results:

What am I missing with this procedure that's preventing me from achieving convergence?

 

 

[Essence]

Could you please create a new question thread pertaining to the follow up questions you have? Thanks.