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-   -   Lifted laminar flames using Stiff Chemistry Solver (http://www.cfd-online.com/Forums/fluent/109881-lifted-laminar-flames-using-stiff-chemistry-solver.html)

jmartrubio November 28, 2012 16:50

Lifted laminar flames using Stiff Chemistry Solver
 
Hello,

I am new in this so please tell me if I haven't expained myself properly or you need more information.

I am using Fluent to simulate laminar lifted flames in 2D of a mixture methane-air. The domain is defined by a velocity inlet in which the composition of methane has a parabolic profile, two walls with a small tilt and an pressure outlet condition in the exit.

I resolve the cold flow to let the species mix and then activate the energy equation. I use Stiff Chemistry Solver with its default parameters, and the default under-relaxation factors also.

To ignite the mixture I patch two regions at high temperature. My problem is that the solution calculated depends on the initial regions set at high temperature. In all the cases the residuals go down to 1E-5 and the solution stays there after hundreds of thousands of iterations.

Do you know what could be the problem?

Thanks a lot for your help.


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