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Old   January 23, 2012, 05:34
Default Flamelet Parameters
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Andre Novgorodcev
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I'm starting to make reactive simulations using Steady Flamelet models. My objective is to simulate a hydrogen flame in air in a tipical bluff-body configuration. I'm using the Burke 2011 kinetic model (8 species + inerts and 19 reactions).

There is any golden rule to determine the following parameters to calculate the flamelet and generate the pdf table?
  • Number of Grid Points in Flamelet
  • Maximum Number of Flamelets

  • Number of Mean Mixture Fraction Points

  • Number of Mixture Fraction Variance Points

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Old   May 20, 2012, 06:28
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Fariborz Soroush
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hi every body
is there anyone here to answer the question?
It's mine too!
Also I want to know if there's any optimum under-relaxations?
My model convergence has many fluctuations.
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Old   November 19, 2012, 16:23
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Hi all ,
As far as i know there isn't any golden rule , however you can validate your results by looking to the Flamelet shape, species , scalar dissipation and mixture fractions .
I am always using the automated refinement with 8 to 40 points /20 flamelets and it gives good results . Check also the time vs . residuels while creating flamletes ,if it is smooth then you are good to go , if on the other hand it takes long time , try to redude the fourrier no. to 1 .
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Old   September 8, 2018, 12:27
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Tariq Ridwan
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Hi Kingpots,

thank you very much for your response, it was really helpful.

Could you shade some light in solving my simulation, please??

I am doing a non-premixed Methane-air combustion which has swirling air-flow involved. I am using both GRI-mech 3.0 and GRI-mech 2.11 chemical kinetics mechanism and using Steady Diffusion Flamelet chemistry model in Fluent non-premixed combustion. Standard k-epsilon Turbulence model and P-1 radiation model is used.

Simulation Results of Velocity and Gas mass-fraction are matching the experimental data in all locations except gas mass-fraction data in two initial upstream locations. In order to get better gas mass-fraction data, I was trying to figure out a way.

I also always used Automated Grid Refinement.

Now the question is, changing (increasing/decreasing) following default values will give better result ??

1) Maximum number of flamelets (default value: 8)

2) How about Initial Scalar Dissipation (default: 0.01)
and Scalar Dissipation Step (default: 5)?

3) Initial number of Grid points in Flamelet- 8 and
Maximum number of Grid points in Flamelet- 64

4) Maximum Change in Value Ratio- 0.5

5) Maximum Change in Slope Ratio- 0.5

I'm attaching the Fluent Flamelet window screenshot as well.

Could you please help me out??
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File Type: png Flamelet Calculation.PNG (107.1 KB, 46 views)
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Old   December 3, 2019, 06:46
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Hi all,
Error while creating flamelet.
Anyone can explain how to use steady diffusion flamelet non-premixed model.

Thanks in advance.
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flamelet, flamelet table

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