combustion of CH4-AIR mixture with concentration gradient
 

Hi all,
I am using the partial premixed combustion model based on the Flamelet Generated Manifold(FGM) model to simulate inhomogeneous methane combustion. The calculation domain is a simple closed two-dimensional rectangle, and the methane inside is a non-uniform state formed after diffusion. (based on ANSYS Fluent 2019R1）

My problem is how to set up the FGM model without changing the original gas concentration.?? 😵 Every time I calculated the flamelet and generated the PDF table, the concentration changed.😣

I have tried the finite rate model in the Species Transport, which can not change the original CH4 concentration.

After looking for some cases and articles, I found that FGM model is basically used for jet flame, but there is little case for closed calculation domain.

Thanks for anyones help.